How to Tune for Smog

8/3/2019 How to Tune for Smog

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How to Tune for Smog

I set my idle exhaust emissions to 0.7% CO (the factory setting is 0.5% to 1.5% CO for mymodel year and transmission type). This produced the following measurements with my ownwide-band O2 tester before any other adjustments:

y Air temp: 60Fy head temp: 315F at 50mph, 390F at 70mph

You want to record the AFR reading from the LM-1 at thesame speeds they use in the smog test + idle. In order to dothis you will need a section of road that is flat and longenough to let you maintain those speeds and quiet enough sothat you are not going to be holding up traffic.

y 0 mph (neutral)y 15mph (2000 rpm in 2nd gear)y 25mph (2000 rpm in 3rd gear)

Normal CO readings. If the combustion process is succeeding at or near the stoichiometricpoint (AFR equals 14.7, Lambda equals 1.0), CO levels during an idle test will typically measureless than 2%.

High hydrocarbon (HC) readings usually indicate excessive unburned fuel caused by a lack ofignition or by incomplete combustion. Concentrations are measured in parts per million (PPM).Common causes include a faulty ignition system, vacuum leaks, and fuel mixture problems.Circumstances that can lead to a high HC emissions are:

o Incomplete combustion due to fouled spark plugs.o Improper timing or dwello Damaged ignition wireso Poor compressiono Vacuum leako Ineffective or faulty air management system (ECM control of air/fuel ratios)

High carbon dioxide (CO2) readings indicate a nearly ideal air-fuel ratio and efficientcombustion

High NOx Readings. Circumstances that can lead to abnormally high NOx emissions are:

o Malfunctioning EGR valveo Lean fuel mixture (AFR above 14.7, Lambda above 1.0)o Improper spark advanceo Thermostatic air heater stuck in the heated air positiono Missing or damaged cold air ducto Combustion chamber depositso Malfunctioning catalytic converter

RPM range AFR %CO

Idle 14.2:1 0.7

light throttle 14.7:1 0.1

half throttle 13.6:1 2.5

WOT 12.6:1 5.0


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Here 20 tips to passing the smog checks at the REF:

1) Get a good Engine Tune, ecu tuning via uberdata, crome, hondata, etc, make sure you use wideband

o2 sensor like Bosch lm-1 or lc-1 to make sure air/fuel ratio is close to 14:7 at most throttle speeds,

which is perfect air/fuel ratio, but at high throttle 13:6. If your car is tuned to 14:7 you should have noproblem passing the CO and HC portion of the test. Almost any setup or engine can pass if it is running

right. (Reduces CO, HC).

2) Check Timing, this is another thing when tuning, make sure there no knock by retarding the timing,

but just make sure stock timing at idle is set to TDC 16. If your running high compression you will need

to run more conservative timing to not increase your NO, but if you retard it too much than CO and HC

numbers jump. REF checks it to make sure its 16 or you fail visual (Reduces CO, HC, NO)

3) Replace O2 Sensor, but if your tuned then closed loop will be fine. I enabled the barometer pressure

sensor and o2 sensor for smog check, ran more efficient but don't need it if your tuned. (Reduces CO,

HC)

4) Replace/Calibrate TPS Sensor, don't forget about this, crucial in passing because if the engine doesn't

know the correct throttle then it will inject the wrong fuel and air into the engine and cause it to fail.

(Reduces CO, HC, NO)

5) Replace MAP Sensor if bad, checks pressure in bar and knows what fuel to use, if your running a 4 bar

map sensor it would be fine as long as its tuned, but oem is recommended if your NA, 4 bar is only

needed if your forced induction. (Reduces CO, HC, NO)

6) Buy a new Catalyst Converter every 3-4 years, if you live in CA you will have to replace this every

other smog check because they don't last more than 3 years, the ref checks under your car to make sure

you have it. Also, if there is a leak between your header and exhaust right where your o2 sensor reads,

then your catalyst converter will get too much air/o2 and will let through too much NOx, and won't do

the job of converting NOx into N and O. So make sure there your exhaust is tied down tight and there no

leaks. Since honda didnt put an egr valve, the only way it can reduce NOx is by overlap and catalyst

converter. (Reduces CO, HC, NO)

7) Replace broken/remove Thermostat, if its broken and doesnt open then you will overheat and lean

out, if its stuck open then you run too cold and too rich, since i was running high compression I had to

remove the thermostat all together, but if you running anything above 11:1 compression then I

recommended spoon or mugen for better cooling, I was running 12:3 compression so I just removed thethermostat and it ran at the perfect temperature (Reduces NO the most, but affects the CO and HC if

running too rich or lean)

8) Radiator fan sensor, helps cool down the engine if its overheating a lot, I had hondata so I just set it to

turn on lower temperature (Reduces NO)


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9) Get colder spark plugs - I used heat range 8 plug, gaped mine to .38, get the right heat range

depending on application and compression, if your running 10:1 then use heat range 6, 11:1 then use

heat range 7, 12:1 and above get heat range 8 (Reduces NO)

10) New Oil and Oil Filter - I recommend Quaker State Full Synthetic, K&N filter, any weight that makes

you consume less oil would be best, I used 10W-30 becuase I couldn't find 20W-50, but recommend20W-50 for high mileage cars. (Reduces NO)

11) Replace Cap, Rotor, and Spark Plug Wires - if your getting backfire then it could be something to do

with these, if your not getting enough spark then you will have unburnt fuel leftover after the burn

(Reduces CO, HC)

12) Use good injectors, I used RC injectors, pinto injectors tend to get dirty much easier, just cover any

aftermarket injectors up so he don't see them or you fail visual, but if there clogged then your engine

could lean out. I recommend if your using RC injectors get a tune, for some reason they run so much

different than stock, they squirt out more so you will need a good tune to compensate, cant just throw

in the same size expecting the same flow. (Reduces NO)

13) Fill your with good Gas that the engine was tuned for, if the car was tuned with 91 then run 91, the

reason I say this is because when you tune to 14:7 air/ratio your tuned for the specific gas, and if you

put anything high octane or lower than you will be running at a different air/fuel ratio and could make

you fail smog, it only works to use octane boosters if your car is dyer need of a tune up, running lean

because of carbon build up in your engine which increase compression so you use an octane booster to

increase the octane to run the higher compression, but if your tuned then there no reason to be

throwing in this stuff, it will make you run worse if that isn't your problem. (Reduce NO)

14) Air filter upgrade, if you got K&N or AEM aftermarket air filter then you changed it from stock andwill probably need a need, but this upgrade is minimum so it can still pass, will need CARB#, but if you

put an intake on expecting it to run good on a stock ecu, it will only hurt you (Reduce CO,HC,NO)

15) Throttle body upgrade, if you increased the size you will need a tune. (Reduce CO,HC,NO)

16) Intake Manifold upgrade, even if its got a CARB#, doesn't mean it will pass with a stock ecu, such as

skunk2 intake manifolds, you need to get it tuned. (Reduce CO,HC,NO)

17) Header upgrade, if you got a better header it must have CARB#, best to use your stock header if your

running a stock ecu, but if your got aftermarket, you might need a tune. (Reduce CO,HC,NO)

18) Camshaft upgrade, if you got something minor like civic type r cams, you might not need a tune, but

if you got toda cams then your going to need a good tune. But like they all say, stock is always a solution

if you can't get the todas to pass (Reduce CO,HC,NO)

19) Valve adjustment, will help it all together. (Reduce CO,HC,NO)


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20) Pistons upgrade, decrease or increase compression will do nothing to your CO and HC, but affect NO

a whole lot. If your running compression higher than 11:1 then your NO will increase regardless but if

your catalyst converter is working properly then it will be cleaning most of this up. A good tune will fix

this problem. (Reduce NO)

Things to know:

CO2 Higher the better (sign of combustion efficiency) 14.7 is the perfect place to be at if its higher than

your running too lean.

O2 should be less than 1% - if it is higher than you got a leak somewhere or its not being efficient in

burning the O2.

CO is incomplete combustion - can be caused by bad ignition such as spark plugs, spark plug wires,

distributor, timing, etc.

HC is unburnt gas (raw fuel) - can be caused by running too rich which can kill the catalyst converter

over time. Misfire or foul out is an indication there too much fuel. Causes can range from o2 sensor,

spark plugs, not enough timing, to other serious problems like bad fuel pressure regulator.

NOx created by high temperatures and high pressure - causes are usually running too lean and can range

from bad catalyst converter, o2 sensor, injectors, radiator, thermostat, timing too advanced, high

compression.

Pick a perfect day, if its cold then make sure the car is warmed up, if its hot just make sure the engine

isn't overheating, but try to pick a perfect day it will do wonders. There no replacement for a good tune,

a tune is everything in passing the emissions test, make sure everything looks stealthy so you pass the

visual, I used a hondata to do all the tuning.

[i]Modified by lek9l at 11:30 PM 8/29/2008[/i]


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Technical facts about the mentioned fuels:

E85 requires 42% more fuel to reach stoich even if that is not what you may come up with when doing

calculations based on the table below. This is because the injector flow is slightly different when using

E85 among many other things I cant really think of at this time (will be added at a later time).

Fuel ........................AFRst ........ FARst ....... Equivalence Ratio ... Lambda

Gas stoich ................ 14.7 .......... 0.068 ................ 1 ................... 1

Gas max power rich .... 12.5 .......... 0.08 ................. 1.176 .............. 0.8503

Gas max power lean .... 13.23 ........ 0.0755 .............. 1.111 ............. 0.900

E85 stoich .................. 9.765 ....... 0.10235 ............ 1 ................... 1

E85 max power rich ...... 6.975 ....... 0.1434 .............. 1.40 ............... 0.7143

E85 max power lean ..... 8.4687 ...... 0.118 ............... 1.153 .............. 0.8673

E100 stoich ................ 9.0078 ...... 0.111 ............... 1 .................... 1

E100 max power rich .... 6.429 ........ 0.155 .............. 1.4 .................. 0.714

E100 max power lean .... 7.8 .... ...... 0.128 .............. 1.15 ................ 0.870

The term AFRst refers to the Air Fuel Ratio under stoichiometric, or ideal air fuel ratio mixture

conditions. FARst refers to the Fuel Air Ratio under stoichiometric conditions, and is simply the

reciprocal of AFRst.

Equivalence Ratio is the ratio of actual Fuel Air Ratio to Stoichiometric Fuel Air Ratio; it provides an

intuitive way to express richer mixtures. Lambda is the ratio of actual Air Fuel Ratio to Stoichiometric Air

Fuel Ratio; it provides an intuitive way to express leanness conditions (i.e., less fuel, less rich) mixtures

of fuel and air.

When driving purely on E85 you can blend it with up to 25% gasoline in case you want to raise the AFR

number used to produce max. power. In that case you can raise the boost even further since the volume

of fuel needed to reach the desired lambda is decreased.

Performance application and fuel needed:

Performance application:

Lets pretend for a while that the ECUs in our cars are pretty good at their jobs. On gasoline it will try to

keep an AFR of 14.7 (lambda=1) all the time at idle, cruise and light load. It will also try to keep a good

AFR at WOT/boost of 13.2-12.5, sometimes even lower than that, probably closer to 11.x.

Why? Because the fuel has a cooling effect on the intake charge and the space in which the combustion

occurs.

As you can see from the table shown above this section, the ideal target AFRs under boost for both


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gasoline and E85 are listed. For gasoline its 13.23-12.5, and for E85 its 8.47-6.975. However, with E85

you will not need to richen the mixture under WOT/boost as far as 6.975 or beyond. It does not need to

be proportionally richer when compared to gasoline.

Why? Again, Because the fuel has a cooling effect on the intake charge and the space in which the

combustion occurs. And at such a low AFR as 9.765 (lambda=1 on E85) or lower the fuel cools pretty

good, dont you think so?

Many people with some experience in mapping an ECU for use with E85 says that as high AFR as 8.5 or

lambda=0.80-0.85 works well. No need to go to the extreme end of the useable scale to get safe power.

It only uses a lot of fuel without giving any benefits.

Since you dont have to richen the mixture as many percent (proportionally) as you have to on gasoline,

you can make more power without having to use as much fuel. Instead you can keep the AFRs leaner

across the board and by doing so you can make room for higher boost without maxing out the injectors.

The burn rate will of course be different for different AFR's. It is a matter of tuning it right and getting

the peak cylinder pressure where you want it (10 degrees after TDC). But if you are around the same

ratio as on gasoline (i.e if you have installed injectors that are almost exactly 42% bigger) you are in the

ballpark and do not have to worry about it. More about this later on.

Fuel needed:

As you will see, both in my article as well as other places on the internet, different fuel requirements are

listed. What numbers will you see and why?

1. A car converted, but not specifically mapped for E85 will consume ~30% more fuel.

2. A car running E85 will require ~42% more fuel.

3. According to your own calculations (if you have bothered to look in to it), it will not quite add up.

Most people scratch their head.

Let me show you a table again:

Mode ........... Gas .... E85 ...... extra % (mass) ... extra % (flow)

Stoich .......... 14.7 .... 9.765 ........ +50.5% ................ +42%

Lean power ... 13.2 .... 8.47 .......... +55.8% ................ +47%

Rich power .... 12.5 .... 6.975 ........ +79.2% ................ +69%

E85 has a higher density than gasoline. The change in AFR from 14.7 (lambda=1 for gasoline) to 9.765

(lambda=1 for E85) is 50.5%. But the resulting flow needed is only 42% greater.


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Explanations to this: E85 will need a fuel flow that is 42% greater than the flow needed for gasoline.

However, it will not use 42% more fuel since it will actually be more efficient. Generally, the engine will

consume ~30% more fuel.

If I am using 46.7lb/hr injectors (45% larger than stock) which are easy to get hold of, my AFRs should

theoretically look like this:

*At idle, cruise and low load (closed loop) the AFR will be 9.56, the O2-sensor sees this and will correct it

to 9.765. A very small correction, and it lies well within the adaptation limits. Not even noticeable as

more than normal adaptation by the ECU.

*When at WOT/boost (open loop) the AFR will be between 8.58-8.13. This looks a little lean according to

the AFR table, doesnt it? It isnt even in the "rich" area according to the table. No worries, the cooling

properties of E85 are pretty good. But in reality I will actually get an AFR of around 8-7.5 since my ECU

wants to run a slightly richer mixture than 12.5 on gasoline. It obviously does not know that it is running

E85...


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ASM:

ASM Pass/Fail

CO HC NO

15mph 25mph 15mph 25mph 15mph 25mph

1.66% 1.46% 204ppm 169ppm 1534ppm 1394ppm

ASM Gross Polluter

CO HC NO

15mph 25mph 15mph 25mph 15mph 25mph

3.16% 2.96% 394ppm 344ppm 2791ppm 2591ppm

I believe the formula on the document is incorrect so I filed a misdemeanor complaint againstBAR under the Business & Professions Code (sounds crazy but that's how CA works I'm sad tosay).

In my opinion the formula should be A + (A+B)/VTW which will calculate the test limits. Forexample, my 78 bus falls into ESC 10 by weight and vehicle type.

Let's figure out the %CO limit.

CO limit A = 1.08 (15 mph), 0.88 (25 mph)

CO limit B = 2025.00 (15mph and 25 mph)

3) Punching those numbers along with the 3500 lbs vehicle test weight into the formula:

1.08 + (1.08 + 2025)/3500 = 1.66 %CO

0.88 + (0.88 + 2025)/3500 = 1.46 %CO

Good: exactly the same as my test report below. Look at the stricter limits for the 79-83 vehicles:

0.88 + (0.88 + 2025)/3500 = 1.26 %CO

0.68 + (0.68 + 2025)/3500 = 1.46 %CO

D'Oh! Even lower limits! What if your 76-78 bus vehicle weighs 4000 lbs?

1.08 + (1.08 + 2025)/4000 = 1.58 %CO

0.88 + (0.88 + 2025)/4000 = 1.39 %CO

I have to conclude from the formula that the heavier your vehicle is the lower the limit and theharder it will be for you to pass.


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A full gas tank and full water tank weighs about 150 lbs. What else do you have inside in yourbus (spare tire, gear stored)?

10. Passing TSI:

For the TSI test you can limit yourself to setting the air fuel ratio (AFR) at idle. If you have goodcombustion the CO numbers will not creep up after they release the throttle. If your engine isn'tburning fuel correctly (weak spark, low compression, etc) then you'll have high HC numbers.

I was naturally unprepared for my first test thinking the smog referee would only be helping meassess my vehicle. Instead he recorded the test results and I had left the checking of the AFR tothe mechanic 5-12 years ago.

Here were my 2002 results:

%CO2 %O2 HC (PPM) CO (%)

Test RPMMEASMEASMAXAVEMEASMAXAVEMEAS Results

idle 876 8.1 7.8 250 73 186 2.50 0.50 2.49 PASS

high rpm 2499 13.9 0.8 200 67 74 3.00 0.90 0.45 PASS

11. Passing ASM (Part 1):

I set my idle exhaust emissions to 0.7% CO (the factory setting is 0.5% to 1.5% CO for mymodel year and transmission type). This produced the following measurements with my ownwide-band O2 tester before any other adjustments:

RPM range AFR %CO

idle 14.2:1 0.7

light throttle 14.7:1 0.1

half throttle 13.6:1 2.5

WOT 12.6:1 5.0


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y Air temp: 60Fy head temp: 315F at 50mph, 390F at 70mph

Whether you are preparing for a test or just failed one, testing and adjusting your emissionsoutput is the next step. There are a couple of traditional ways to get you bus in tune but consider

the drawbacks:

y Use the exhaust sniffer at your mechanic but it only works at idle while the test stimulatesdriving on a dynomometer

y Race prep shops that have a dyno and sniffer but will either a) refuse to tune your bus or b)charge you a small fortune for the service unless you have friends in the right places

y The smog pre-test gives you exact results but the test costs full price and won't offset the cost ofthe real test. On top of that you'll have no idea what your emissions will be after a tune-up until

you get re-tested which may require several trips ($$$).

This is where a portable wide-band O2 tester is far more useful. Armed with one of these, alocation to mount the sensor and a tachometer, you are on your way to independence as far assmog testing is concerned (one of the last bastions of automotive repair whose price have comedown to the hobbyist level thanks to low cost technology from Bosch: the LSU-4 O2 sensor).

You will also need a chart to convert readings because the testers only display Lambda

and AFR while the smog test registers %CO, a tachometer and a location to mount thesensor.Download the Conversion Chartand print it out.

A wide-band tester like the Innovate LM-2 (replaces LM-1) is about $350 but you'll recover themoney over several tests by not having to pay for testing through other means and you'll have the

personal satisfaction of "beating the system". I use mine to help friends and other bus ownerswho got trapped between ignorant mechanics and the smog system.

Innovate is by far the best product available as rated for cost/accuracy. They do make a cheaperLC-1 cable ($199) which connects to your laptop but for easy of use and setup, the LM-1 is theway to go.


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You'll need to get someone (perhaps a muffler shop) to weld an oxygen sensor bung onto yourexhaust unless you have a CAT from the factory 75-79 setup with a test port. One such unit is theEMICO replacement CAT which the FI beetle also uses (hence the 043 part number).

Note: this cat does not come with a plug. See a muffler shop for a plug to cover the hole or use

an old worn out O2 sensor when not in use.

Also note that this CAT is for federals models only (see Why people unknowingly fail).

With my engine, I measure about 14.5:1 in those two gears at 2000 rpm. If your measurements are

accurate (thanks to LM-1's accuracy) you should have no trouble passing if you can keep your reading at

14.0:1 or higher.

A cold engine stumbles and runs too rich. Before taking your test, make sure you run the engine

at 50mph for 20 minutes to ensure that it's warmed up for the test (heat soak will keep it warmwhile you are waiting in line for the test for any reasonable length of time).

Here are my 2004 results:

%CO

2%O2 HC (PPM) CO (%) NO (PPM)

Tes

t

RP

MMEAS

MEA

S

MA

X

AV

E

MEA

S

MA

X

AV

E

MEA

S

MA

X

AV

E

MEA

S

Result

s

15mph

1990 13.9 1.2 204 49 48 1.66 0.30 0.19 1534 592 652 PASS

25mph

2018 13.8 1.5 169 40 31 1.46 0.27 0.11 1394 500 563 PASS

Here are my 2006 results (not much change except my NOx has gone up by 30%):

%CO

2%O2 HC (PPM) CO (%) NO (PPM)

Test RPM MEASMEA

S

MA

X

AV

E

MEA

S

MA

X

AV

E

MEA

S

MA

X

AV

E

MEA

S Results

15mph

2068 14.2 1.4 204 49 50 1.66 0.30 0.16 1534 592 849 PASS

25mp

2072 14.1 1.6 169 40 35 1.46 0.27 0.13 1394 500 727 PASS


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h

The LM-1 was right on the mark! Notice my NOx readings are rising? This is typical as anengine ages.

Functional items they did not test according to the report:

y Catalytic Converter (CA only)y EGR Functional (got lucky)y Thermostatic Air Cleaner (Mitchell error)y Air Injection (another error)y Fill pipe restrictor (CA only)y MIL/Check Engine Light (no EGR light on Federal models)y Oxygen Sensor (only for 79 CA model)

It would seem that BAR now knows what items are not specific to my model. Good news and

somewhat gratifying having sent in my feedback to Mitchell 2 years ago. I no longer have toworry about my smog sticker being incorrect (the database is correct and where it's not the smogtechs know what to correct).

When you pass you are issued a certificate number which the DMV uses during the registrationprocess. The results are sent electronically from each smog station to the DMV to help eliminatefraud.

CA model:

HC: 0.63 (0.08)

CO: 12.40 (2.4)

CO2: 473 (351)

NOx: 0.93 (1.48)

y Rich mixtures == high levels of HC and CO, lower levels of NOx.y Lean mixtures == low levels of HC and CO but high combustions temperatures producehigh NOx levels.


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y High CO (aka too rich). When the air fuel ratio is incorrectly set, the sniffer knowsimmediately and this results in a fail. Sometimes timing is the cause, other times it's the mixture.Either way, the cure is often simple: get a tune up at a repair shop that has an exhaust analyzer.Serious engine problems may prevent setting the AFR properly which will require furtherinvestigation because setting the AFR is the final step in the tune-up process. The only downside

to the shop's adjustment is that if you are near the borderline of the test limit at the shop duringthe test you may fail the smog test. This may either be because the shop's equipment is out ofcalibration or simply because the equipment is stationary and you are unable to simulate thedyno test. Either way, confirm their reading before you pay.

y High HC. Excessive hydrocarbons can be caused by a clogged catalytic converter or it can beas simple as a larger than normal amount of ignition misses. It's normal for the engine to missonce in a while at idle but if it happens too much then unburned fuel will exit the tailpipe. Lowcompression and valve timing can cause the engine to miss and it can also be induced to misswhen the fuel injectors are clogged or vacuum leaks (false air) are introduced.

You want to record the AFR reading from the LM-1 at the same speeds they use in the smog test+ idle. In order to do this you will need a section of road that is flat and long enough to let youmaintain those speeds and quiet enough so that you are not going to be holding up traffic.

y 0 mph (neutral)y

15mph (2000 rpm in 2nd gear)y 25mph (2000 rpm in 3rd gear)

LSVTEC

11.7:1 C/R

RC 310cc Injectors

Fuel Pressure at 43 psi

Hondata A/F tuning

18 degrees of timing

NGK BCPR6ES-11 plugs

...........and91 octane.

-Sparkplugs NGK BKR7E-11 (colder plugs to help the heat)

-Distributor Cap & Rotor (New OEM)


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-Sparkplug Wires OEM NEW (decided to go with OEM instead of NGK) - those will be in tomorrow

-Retarded Timimg to 12-13 BTDC (I eyeballed it since i dont have an advanced light)

-O2 Sensor (replaced with another OEM used 02. Ohm reading on it is 15 i think)

-Raised Fuel Pressure (38psi with B&M FPR)

-New Exhaust Manifold Gasket & Exhaust Pipe Flex Gasket (the one right before the cat)

-GTPE full bottle

-Tested Injectors and all are ok

check this out...

i took, stock p06 map... export fuel/timing

open p30, import fuel/timing from p06

remove knock, eld and injector test

rev limit 7500launch control a 3700

full throttle shift 7200

shift light 7000

removed checksum

added quick datalogguer

add boost tool

but injector are still 240cc

Following are a few general facts and tips to keep in mind when using the gas analyzer:

1. High Carbon Monoxide (CO) readings usually indicate a fuel mixture richer than ideal(rich mixture - air fuel ratio below 14.7). In general CO is an indicator of combustionefficiency. The amount of CO in a vehicles exhaust is directly related to its air-fuel ratio.High CO levels result from inadequate O2 supply needed for complete combustion. Thisis caused by a too rich mixture - too much fuel or not enough air (AFR readings belowthe optimal 14.7, Lambda below 1.0). Circumstances that can lead to high CO emissions:

o Low idle speedo Improper float settings in carbureted vehicleso Dirty or restricted air filterso Excessively dirty or contaminated oilo Saturated charcoal canistero Non-functioning PCV valve systemo Improper operation of the fuel delivery systemo Improperly functioning thermactor system


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NOTE 1.Catalytic converter intervention and CO concentrationsHigh CO readings at the tailpipe are an clear indication that there is a problem in at leastone part of the system, but a CO reading that appears within "normal" ranges or is onlymodestly elevated is not necessarily a reliable indicator of proper or even acceptablesystem performance. Low range CO readings are possible, and not uncommon, from a

malfunctioning engine equipped with a properly functioning catalytic converter. In suchcircumstances, truly elevated pre-catalytic converter CO levels will be masked by thecatalytic converter and the potential for an CO problem must be further evaluated in thecontext of other readings of abnormal gas concentrations and AFR/Lambda readings.

NOTE 2.: Great caution must always be exercised when dealing with CO.

Concentrations of


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5. Oxygen (O2) readings. Oxygen, measured as a percentage of the exhaust volume,reflects the amount of gas remaining in the exhaust sample after the combustion processhas taken place. Ambient O2 readings should be about 20%, reflecting the natural amountoxygen found in the air. The ideal range for vehicles without a secondary air injectionsystem is less than 1.5%. If there is an air injection system, O2 levels will typically fall n

the range of 3% to 4%. Pinching off the air hose of a vehicle equipped with air injectionshould produce O2 levels similar to those found for vehicles without air injection.6. High oxygen (O2) readings indicate too lean an air-fuel ratio (AFR higher than 14.7,

Lambda greater than 1.0). Circumstances that can lead to high O2 emissions are:o Lean fuel mixture (AFR above 14.7)o Vacuum leakso Ignition related problems causing misfires.

7. Low O2 indicates a rich fuel mixture (AFR below 14.7, Lambda below 1.0).8. High carbon dioxide (CO2) readings indicate a nearly ideal air-fuel ratio and efficient

combustion9. Low carbon dioxide (CO2) readings indicate a fuel mixture either too rich or too lean,

exhaust system leaks, or sample dilution.10.Oxides of Nitrogen readings. Oxides of nitrogen (NOx), including nitric oxide (NO) andnitrous oxide (NO2), are formed if the combustion temperatures within the combustionchamber exceed some 2,500F. This can occur when the engine is under load. Whenexcessive temperature conditions exist, the greatest amount of NOx is typically producedat the stoichiometric point (AFR 14.7 or Lambda of 1.0) as the engine is under a lightload. If the combustion process within an engine is burning fuel at or near stoichiometricpoint, NOx levels on acceleration will typically read significantly higher than thosemeasured at cruise and during deceleration. Typically, the NOx readings at idle will be 0PPM.

11.High NOx Readings. Circumstances that can lead to abnormally high NOx emissionsare:

o Malfunctioning EGR valveo Lean fuel mixture (AFR above 14.7, Lambda above 1.0)o Improper spark advanceo Thermostatic air heater stuck in the heated air positiono Missing or damaged cold air ducto Combustion chamber depositso Malfunctioning catalytic converter

NOTE. Catalytic converter intervention and NOx concentrationsHigh NOx readings at the tailpipe are an clear indication that there is a problem in at leastone part of the system, but a NOx reading that appears within "normal" ranges or is onlymodestly elevated is not necessarily a reliable indicator of proper or even acceptablesystem performance. NOx readings at or near "normal" are possible, and not uncommon.From a malfunctioning engine equipped with a properly functioning catalytic converter.In such circumstances, truly elevated pre-catalytic converter NOx levels will be maskedby the catalytic converter and the potential for an NOx problem must be further evaluatedin the context of other readings of abnormal gas concentrations and AFR/Lambdareadings.


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12.Low NOx readings. There is, effectively, no reading for NOx that can be characterizedas too low or below optimal. NOx is naturally 0 ppm at idle. NOx concentrations mayappear normal even in a rich burning environment where the AFR is well below 14.7(Lambda below 1.0).

Facts to Remember

The byproducts of combustion are dependent on the air-fuel ratio.

13.O2 combines with HC to form CO2 and H2O.14.O2 combines with CO to form CO2.15.CO is an indicator of air-fuel mixture richness.16.HC is an indicator of fuel mixture leanness (or richness) and misfires.17.CO and O2 are equal at the stoichiometric air-fuel ratio.18.O2 and CO2 are indicators of exhaust system integrity, sample hose and probe integrity,

or both.

19.CO2 is an indicator of combustion efficiency that peaks at or near the stoichiometric air-fuel ratios, and decreases with lean or rich air-fuel ratio.

20.Air injection systems dilute the exhaust sample with O2.21.O2 is essential for proper operation of the catalytic converter. Its concentrations are

essentially unchanged by the catalytic converter, providing a "window" through theconverter to the engine. O2 levels are higher on vehicles with properly operating airinjection systems.

22.IfCO goes up, O2 goes down (inversely related)23.IfO2 goes up, CO goes down (inversely related)24.With the air injection system disabled and the CO above 1%, the catalytic converter is

oxygen-starved. Without O2, it does not fire, allowing exhaust concentrations to be more

like readings taken ahead of the converter.

If readings are within the manufacturers or local/state/federal allowable limits, it can generallybe assumed that the fuel, ignition, and emission control systems are functioning properly. If theyexceed the limits, repairs or adjustments are probably called for.

The chart below lists some of the kinds of problems that could result in abnormal gas readings.

(Legend:L = Low, H = High , M =Moderate)

CO CO2 HC O2 Possible Problems

H L H H Rich mixture with ignition misfire

H L H L Faulty thermostat or coolant sensor

L L L H Exhaust leak after the converter

L H L H Injector misfire, catalytic converter operating

H L ML H Rich mixture

H H H H Injector misfire, catalytic converter not working; combination of rich mixture


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and vacuum leak

L L H HIgnition misfire; lean condition; vacuum or air leak between air flow sensorand throttle body (false air)

L H L L Good combustion efficiency and catalytic converter action

L L L All systems operating within tolerance; normal reading

The following table lists some of the results possible when the AFR (air-fuel ratio) is sustained atconditions ranging from too lean to too rich.

Conditions Results

Too Lean Poor engine power

Misfiring at cruise speeds

Burned valves

Burned pistonsScored cylinders

Spark knock or ping

Slightly Lean High gas mileage

Low exhaust emissions

Reduced engine power

Slight tendency to knock or ping

Stoichiometric Best all-around performance

Slightly Rich Maximum engine power

Higher emissions

Higher fuel consumption

Lower tendency to knock or ping

Too Rich Poor fuel mileage

Misfiring

Increased air pollution

Oil contamination

Black exhaust

Gap Plugs to 0.45-0.52

Install 2 Catalyst Converters

New o2 Sensor


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Fix Thermostat if needed

Readjust Valves check cam gears

Retune ECU with more fuel

Install 270CC injectors

Put APC wires

Fix Idle

HIGH HC Causes

o2 Sensor Bad

Bad Spark Plugs

Bad Spark Plug Wires

Bad Timing

Bad Fuel Injectors

Caused by Ignition and Fuel Problems

HIGH CO2 Causes

Bad Fuel

Bad o2 Sensor

Partial Burned Fuel Mixture

HIGH NOx Causes

Bad Timing

Temperature in Cylinders is over 2500 Degrees F

Lean Fuel Mixture

Catalyst Converter


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If spark plugs are old change them. You can also go to a hotter plug.

Advance timing

Clean injectors if EFI

Don't use any Octane levels higher then is needed for engine.

Are you getting a good burn? Hotter plugs, narrowing the gap, increasing spark, advancing timing,

running higher octane gas, etc. just to get it through inspection.

Again...Do not use rubbing alcohol. It will dry out your rubber seals and gaskets. Denatured alco hol will

do the trick. Just go to home depot and go to the paint thinners. You'll find a quart there for like $5. Mix

that with a 1/4 tank of gas and get it smogged. I did this to get a 750il with a set of bad catalytic

converters to pass.

At a hardware store, it is called denatured alcohol. It used for dissolving shellac for wood finishing.

If you need pure Ethanol it comes from a Liquor Store as Ever Clear. That is about as pure as one can

purchase it without a commercial license, or Bond paid.


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100% Ethanol can be found at hardware and chemistry stores or ordered online.

E85!

Full-screen

Joes Circle K (Pearsons Fuel), Perris, California, Latest Reported Price: $3.75 (Submitted by

TravelSoftballDad)

on:

Station Address: 19248 Harvill Ave, Perris, California

Retard the timing, run the tank almost dry, get the cats real hot, then pour in a litre of methyl hydrate.

Car will smell like vodka, and you'll pass unless you have serious issues...

I bought 2 gallons of E98 ($4/gallon) last night and mixed half-gallon of it with denatured alcohol that

was left in my tank. Logs indicate everything normal, but the car kinda feels like it has more in it now.

Side note, E98 smells like tequila, and really makes me nauseous ( I HATE tequila!!).

1. Hydrocarbons - may be due to "ignition system (plugs, wires, timing, etc.), air/fuel mixture or fuel

delivery (carburetor or fuel injection), slow reacting oxygen sensor, diluted engine oil, or a dirty air

cleaner."

Solutions - Change engine oil, O2 Sensor (MAF and MAP), plugs, and Air Filter. You can't change timing

on 3.1 motor. But, if your intake valve seals are shot, you will be sucking oil into engine...what is your oil

consumption??????


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2. Carbon monoxide - due to partially burned fuel molecules....problems with the air/fuel mixture or fuel

delivery (carburetor or fuel injection), slow reacting oxygen sensor, diluted engine oil, or a dirty air

cleaner."

Solutions - Change O2, MAF, MAP sensors...and oil and air filter.

3. Nitric oxide - "created by high combustion chamber temperatures..Excessive amounts can be caused

by...inoperative or clogged exhaust gas recirculation system, ignition timing, lean fuel mixture, or an

inefficient or inoperable catalytic converter."

If your exhaust to intake circuit is plugged, not enough exhaust gas will pass into engine.

How many miles on this engine, and when was last test?

The blend changeover triggers a change in the AFR because the ethanol percentage varies from 70% to

85% depending on the seasonal temperatures where you live. 70% ethanol content is the minimum

percentage rating for Winter Blend E85. There is a middle grade (class 2) during Spring and Fall with a

minimum of 74% ethanol. Summer Blend has a minimum of 79% but all variations are still called E85 for

a recognizable common name. This changeover of blends varies per climate (NY goes to Winter Blend

much sooner than Georgia). To see the complete chart by state, GO HERE.

IGNITION TIMING

In addition to fuel changes, there are also other parameters that can be altered, such as ignition timing

advance to take advantage of the 105 octane rating of E85. The ethanol is slower to ignite, and more

timing can be added at max power without the worries of detonation. Our project car sees about 21degrees of timing at 6500 rpm on a stock engine. That simply isn't capable with 93 octane gasoline. The

benefit is a modest 5-10% increase in horsepower. It is a comparable result to high octane race fuel,

without the need to charge your buddies $10 a ride to pay for your fuel needs!

Understanding Air/Fuel ratios

This article assumes you already understand the concept of the air/fuel ratio (AFR), but if not,familiarize yourself by visiting this Wikipedia link. You may have already read that E85 has a


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different stoichometric air fuel ratio than gasoline's 14.7. The stoichAFR for E85 (at 85%Ethanol) is 9.76. The stoich value represents an ideal perfect burn of the fuel usually used at partthrottle conditions. Full throttle conditions require a richer mixture than stoich to prevent thedreaded detonation, or pinging.

However most AFR gauges you can purchase to display a numerical value of the AFR, are showing youvalues for gasoline. This is where it can get tricky, and it's important to understand how this ratio works

on both gasoline and ethanol-based fuel.

All AFR's regardless of fuel type work off of a common number called Lambda. A value of 1.0 in Lambda

represents the stoich for any fuel. Gasoline is Lambda 1.0 at stoich. E85 is Lambda 1.0 at stoich.

If you already have a standard gasoline AFR meter hooked to a wideband O2 sensor, you can still use the

displayed gasoline AFRs in determining your engine's true AFR. For example, if your gasoline meter is

showing 14.7, then we know this is Lamda of 1.0. The equivelent on the E85 side is around 9.7.

Therefore you can conclude that the 14.7 you see on the gauge is a true AFR of9.7. This allows you to

effectively use existing gasoline AFR components or software to tune an E85 Mustang without buying

special equipment. Simply use the same target AFRs on your gasoline gauge that you normally targeted

for gasolline.

For a late model modular Ford engine, we can tell you that it requires about 20% more fuel at partthrottle, and about 40% more fuel at wide open throttle (WOT) so ensure you have adequate fuel flow

to the cylinder before you begin. This is where the experience of a professional tuner becomes

important to understand just how much fuel to add and when, to make the perfect fuel curve.

I have a fully built NA GSR 12.6 compression and had the same problem of not passing DEQ. Every part

that could fail I failed pretty bad. Thank goodness for s300. I leaned the fuel and retarted the timing

which then AF read about 17, which lowered my HC levels. then my NO levels increased. I put 2 cats in

parallel. I brought my laptop to the testing place and hit enter on the fly and did the test. I passed and

jumped in to my car reloaded the tune and off I went.

here's how to hook up an LC1 to an OBD1 honda ecu

LC1 wires:

brown (analog 2) this is your wideband signal, connect to D10 (ELD) on your ecu

yellow (analog 1) this is your narrowband signal, connect to D14 (O2 signal)

black (calibration button/light) connect to the red button and light then ground to chassis

green/white (signal grounds) connect these to D22 (sensor ground)

blue (heater ground) also connect to D22 but not to the same point as green/white - I used a copper bar

and connected green/white on one end and blue on the other and D22 to the middle - that way they're

all grounded to the same place but their signals won't interfere with each other

red (12 power) connect to A25


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Then go into hondata Options > Settings > Wideband Lambda and tell it that 0v is 7.35 af and 5v is 22.39

Documents

How to Tune for Smog