How Mazda's 2.3L DISI Turbo Factory Boost Control System Works v1.00

8/13/2019 How Mazda's 2.3L DISI Turbo Factory Boost Control System Works v1.00

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COBBTUNINGTechnical Documentation

How Mazdas 2.3L DISI Turbo Factory oost !ontrol System "or#s $%.&&

This document is intended to assist you with the understandin' o( how turbo boost )ressure is controlled on a turbo*

char'ed Mazdas)eed 3+ Mazdas)eed ,+ or !-*. This document is intended to show you details about how the stoc# boost

control system has been set*u). This document is bro#en down into (our cha)ters/ Hardware+ 0lumbin'+ Hardware Function+

1 Mechanical !alibration. 0lease read the (ollowin' thorou'hly be(ore you attem)t to modi(y your Mazdas)eed3 with theAccessPORT

TMhand*held ! )ro'rammer. In the AccessTUNERProfessionalTMor AccessTUNER RACETM

so(tware+ table descri)tions and tunin' ti)s (or most o( the tables are )ro$ided and can be accessed by )ressin' the 4F%5 #eywhile that table is hi'hli'hted in the Table List.

"e would li#e to 'o into (urther detail about the sa(e'uards and ad$anced tunin' (eatures that are a$ailable throu'h

the AccessTUNERso(tware. The boost control system uses a closed*loo) tar'etin' system which does e$erythin' it can to

ma#e the boost control system consistent. y em)loyin' this closed*loo) boost control system the electronic control unit

6!7 can use its s)eed to brin' down boost in o$erboost situations and raise the waste'ate duty cycles 6"8D!7 (orunderboost situations. The stoc# boost control system is much (aster than any human analysis and in)ut/ we hi'hly su''est

you use it to your ad$anta'e. 9nce the stoc# boost control system is (ully understood you will (ind it easy to tune oninternally or e:ternally waste'ated turbos. These $ehicles are a bit uni;ue in that they do not tar'et boost (or "9T

conditions+ they sim)ly tar'et tor;ue.

Chapter 1 Hardware

Turbo*


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suc#in' air in and the outlet is )ressurized with the inta#e char'e. =e:t is the center section which contains the bearin's+

sha(t+ and the oil and anti*(reeze )assa'e ways/ the com)ressor and turbine wheels are also attached to the sha(t in this

section. The third section is the turbine section which consists o( the turbine wheel and turbine housin'. This section also

contains a machined by*)ass (or the waste'ate $al$e to seat a'ainst. The last com)onent o( a turbo char'er is the waste'ate

$al$e and waste'ate actuator which control the waste'ate $al$es mo$ement. "e hi'hly recommend that you use a

turbochar'er which has both an oil and water cooled center section/ turbochar'er lon'e$ity is com)romised when only oil is

used to cool the turbochar'er center housin'.

Wastegate Actuator* < s)rin'>dia)hra'm based mechanism which controls the mo$ement o( the waste'ate $al$e. < turbo

waste'ate is normally closed+ (orced shut by a com)ressed s)rin' inside the actuator canister.


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"e will brea# down the )lumbin' o( the (actory boost control system into 3 sections o( $acuum line+ and , attachment

)oints. 0lease loo# at the (ollowin' )icture where we ha$e the three basic len'ths o( $acuum line and the , attachment )oints

labeled. Three o( these lines are )ressurized while the $ehicle is under load and the one $acuum line which 'oes to the turbo

inlet tube is under a $acuum which is created by the turbo suc#in' air into the com)ressor housin'.

Line % which can only be seen (rom under the chassis )lumbs the ni))le on com)ressor outlet to the lar'er+ bottom ni))le on

the waste'ate acutator. This line contains the brass restrictor )ill+ which is actually )ressed inside the com)ressor housin'ni))le. This is a $iew (rom the bottom o( the turbochar'er.

Line 2 )lumbs the smaller+ to) ni))le on the waste'ate actuator to the waste'ate solenoid $al$e. This is a $iew (rom the to)

o( the turbochar'er.

Copyright 2009 Cobb Tuning, Inc. All rights reserved.


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Line 3 )lumbs the other ni))le o( the waste'ate solenoid $al$e to the turbo*inlet )i)e. This $iew is (rom the to) o( the

turbochar'er.

Chapter 3 Hardware Function

Turbo* The (unction o( a turbo is to com)ress the inta#e char'e+ creatin' a 'reater $olumetric e((iciency (or the internal

combustion en'ine.

Wastegate Actuator & Wastegate Valve* < waste'ate actuatorBs (unction is to control the waste'ate $al$e. The waste'ate

$al$e mana'es the e:haust ener'y bein' directed into or by*)assin' the turbine housin'. I( the waste'ate $al$e is (ully

closed+ more e:haust ener'y is directed into the turbine housin' causin' the sha(t s)eed o( the turbo char'er to increase and

the relati$e )ressure 6boost7 to increase+ all within the e((iciency ran'e o( the turbo and the restrictions o( the inta#e ande:haust systems. I( the waste'ate $al$e is o)ened the e:haust ener'y by*)asses the turbine wheel and 'oes into the down)i)e

so that the turbo sha(t s)eed decreases or remains constant. 9)enin' the waste'ate $al$e will 'enerally lower relati$e

)ressure 6boost7 )roduced by the turbo.

=9TC The M9A boost you run+ the LSS waste'ate you need>use. So unless you want to run less )ressure than stoc# and>

or ha$e un*tunable boost )roblems+ we su''est that you do not )ort your waste'ate by hand. "e su''est you lea$e yourwaste'ate+ the area around it+ the turbine housin'+ etc. alone and tune your boost cur$e throu'h the )ro)er means.

Wastegate Solenoid Valve* The (unction o( this de$ice is to control the amount o( air )ressure bein' bled away (rom the

waste'ate actuator. < &@ "aste'ate Duty !ycle 6"8D!7 settin' will allow the solenoid to stay (ully closed/ which will

(orce the turbo boost )ressure to )ush o)en the waste'ate $al$e and the en'ine will run mechanical boost )ressure+ which can

be anythin' (rom *%&)si8. < %&&@ "8D! settin' will bleed o(( the air (rom the "8 actuator throu'h the solenoid $al$e

attem)tin' to #ee) the "8 $al$e shut/ which will (orce the turbo to run ma:imum boost )ressure. This $al$e is considered to

be normally closed when no )ower is a))lied to the $al$e.

Primary Restrictor Pill* This com)onent limits the amount o( )ressurized air (lowin' (rom the com)ressor housin' ni))le.

The )rimary restrictor )ill restricts the air (low so the waste'ate solenoid $al$e and waste'ate actuator are not o$erdri$en+

which would (orce the waste'ate $al$e to o)en )rematurely. The stoc# 2.3L DISI restrictor )ill ori(ice measures at

a))ro:imately &.&%E5 >* &.&&35

Vacuum Lines* ?acuum lines )lumb )ressurized air to the )ro)er com)onents so the Mazda boost control system wor#s

)ro)erly.

ECU* This is the master de$ice which controls the waste'ate solenoid $al$e+ the sla$e de$ice+ so that the tar'eted boost load

is obtained.

The (actory boost control system bleeds air )ressure throu'h the waste'ate actuator to the inta#e or turbo inlet )i)e. "ith this

de$ice set at &@ waste'ate duty cycle throu'h the !M calibration+ all o( the air )ressure 'enerated at the com)ressor

housin' will be a))lied to the waste'ate actuator (orcin' the waste'ate $al$e to (ully o)en. "hen the waste'ate actuator is

(ully o)en+ the $ehicle will run mechanical boost )ressure which can be anythin' (rom *%&)si8 on ori'inal e;ui)ment



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manu(acturer 69M7 turbochar'ers. "hen this de$ice is )ro'rammed to %&&@ waste'ate duty cycle throu'h the !M

calibration+ all o( the air )ressure 'enerated at the com)ressor housin' will be allowed to )ass throu'h the waste'ate actuator

allowin' the waste'ate $al$e to close. The (low is limited by the size o( the hole in the restrictor )ill located in the

com)ressor housin' ni))le. The waste'ate $al$e will only close as much as it can 6ta#in' into consideration that the e:haust

'as )ressure between the e:haust )ort and the turbochar'er is 'enerally 'reater than the mani(old )ressure the turbo is

'eneratin'7 with the e:haust 'as )ressure )ushin' on the waste'ate $al$e.

=9TC I( you run a turbochar'er beyond its com)ressor e((iciency ran'e+ it will turn into a (lame thrower.

Chapter 4 Mechanical Calibration; Mechanical Tuning and Boot Control !"tem Calibration #ing the

AccessTUNERPROfessional or RACE!o$tware%

Mecanical Tuning

Gou can mechanically tune the boost control system by chan'in' the size o( the center hole in the restrictor )ill/ since this

restrictor )ill is actually )ressed inside the com)ressor housin' ni))le+ we hi'hly su''est you lea$e the stoc# restictor )ill in

tact7. The middle o( this restrictor )ill has a len'thwise hole )recisely machined to a certain s)eci(ication so that it wor#s withthe (actory waste'ate actuator and the waste'ate duty cycle settin's in the stoc# !. The size o( this center hole can be

chan'ed in order to mechanically assist boost control.

< smaller diameter hole in the center o( the brass restrictor )ill will ha$e a hi'her tendency to create boost s)i#e in thesystem and re;uire less waste'ate duty cycle to run hi'her boost. The lar'er the diameter hole in the center o( the restrictor

)ill+ the less chance the boost control system will boost s)i#e and the 'reater waste'ate duty cycle you will need to run inorder to )roduce hi'her boost. I( you ha$e a stoc# turbo and are runnin' an AccessPORTma)+ you ha$e no reason to

modi(y your restrictor )ill. I( you ha$e installed a new turbochar'er and you are usin' the stoc# boost control system to tune

boost+ )lease $eri(y that the $acuum line comin' o(( the com)ressor housin' contains a restrictor )ill with a hole machined in

the center o( the )ill.

The stoc# boost control system most commonly uses a restrictor )ill with a center hole size o( &.&%E5 >* &.&&35

For lar'er*than*stoc# turbochar'ers or turbochar'ers with a stron'er mechanical s)rin' in the waste'ate actuator you will

need to use a restrictor with a lar'er center hole+ somethin' alon' the size o( &.&25*&.&,&5 >* &.&&%5



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For similar*to*stoc#*sized turbochar'ers with a wea#er mechanical s)rin' in the waste'ate actuator you will need to use a

restrictor with a smaller center hole+ somethin' alon' &.&25*&.&&5 >* &.&&%5. e $ery care(ul when usin' a restrictor with

a center hole o( this size+ there is a hi'her tendency (or the system to boost s)i#e and you will need less waste'ate duty cycle

to run hi'her boost.

=9TC The hole in the restrictor )ill can always be machined to a lar'er diameter. e sure to ma#e $ery small increases in

the diameter o( the hole. I( the center hole is machined too lar'e you will not be able to hit your boost tar'etse$en with%&&@ waste'ate duty cycle.

The location o( the threads can be located at either end o( the waste'ate actuator rod+ see the below )icture where it

demonstrates the threaded section is closest to the "8 actuator dia)hra'm.

Gou can mechanically tune the boost control system by )re*loadin' the waste'ate actuator arm/ adJustment o( the waste'ate

actuator rod 6i( the rod len'th is not (i:ed and adJustments can be made7 will allow )ro)er calibration and some additional

mechanical tunin'.


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How Mazda's 2.3L DISI Turbo Factory Boost Control System Works v1.00