# pjb,s e/bay build up

**URL:** <https://forums.speedlife.net/t/pjb-s-e-bay-build-up/241027>\
**Category:** Builds\
**Created:** [December 28, 2008, 2:38pm UTC](https://forums.speedlife.net/t/pjb-s-e-bay-build-up/241027 "2008-12-28T14:38:15Z")\
**Posts on this page:** 1\
**Showing post:** 348

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**Author:** ![PJB](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/pjb/32/6389_2.png) [@PJB](https://forums.speedlife.net/u/PJB)\
**Post date:** [September 9, 2009, 3:21am UTC](https://forums.speedlife.net/t/pjb-s-e-bay-build-up/241027/348 "2009-09-09T03:21:16Z")

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> [@WTB : 05 STi or Evo (maybe other years)](https://forums.speedlife.net/t/wtb-05-sti-or-evo-maybe-other-years/22633/29):
>
> PJB:
> 
> Are you using a granetelli? If so which one?
> 
> Your computer is always expecting a 0-5.5v dc signal. The voltage to flow curve is not linear, the MAF is VERY sensitive to low flows, and less sensitive as flow increases.
> 
> The Aftermarket mafs are generally bigger physically, with the same sensor. So the curve will be the same, but the amount of flow that 5.5v represents is much more flow.
> 
> To compensate for this you would need bigger injectors. These injectors should have the same percent change in injector flow as the maf. So if your maf can flow 20% more, your injectors should flow 20% more. This keeps everything within the adjustment window of the stock ECU.
> 
> What about all your OTHER sensors? Have you checked the resistance and voltages of the IAT, MAP, and whatever other sensors you might be using? Perhaps there are sensors you SHOULD be using but are not. Perhaps your sensor problem is a sensor that does not exist but should be there…
> 
> What about O2 sensors? do you have those? Are you running a simulator? New exhaust headers?
> 
> You said you already checked the injectors. So I would look at:
> 
> 1. Oxygen sensors. (they directly control fuel trim)
> 2. Maf sensors (also controls fuel)
> 3. MAP (ditto)
> 4. IAT (yep)
> 
> Could you perhaps try to put together a VERY detailed explination of how the engine runs and what changes happen when you unplug things…
> 
> Good luck!

Im using a C&L 73mm MAF. It uses a stock sensor with a different housing and sample tube.

There are two oxygen sensors on the car. Ive got 30# injectors. Stock is 19 and with my previous setup I had 24’s. The headers are the same as before.

The only sensor not being used is the EGR and Ive got a plug in eliminator for it.

Im not sure if the other sensors were checked out.

Ill try to get a better idea of whats going on.

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