Factory ECM, Blower & AFPR Question
Thread Starter
Instructor
Joined: May 2000
Posts: 150
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From: Denver, CO
Factory ECM, Blower & AFPR Question
Have a question about using the factory ECM on a mildly blown engine – 6 psi - with an AFPR that increases fuel pressure as boost comes on.
A boosted engine runs better at a richer mixture (say 13:1) than a NA engine, but if I adjust the fuel pressure to run richer, will the ECM back off the injector PW to try and keep the mixture at 14.7:1?
What is a good method for dealing with this so I keep the boosted mixture richer than the ECM wants to see?
I’m considering an additional injector controller instead of the AFPR, but the problem with the ECM is still the same.
A boosted engine runs better at a richer mixture (say 13:1) than a NA engine, but if I adjust the fuel pressure to run richer, will the ECM back off the injector PW to try and keep the mixture at 14.7:1?
What is a good method for dealing with this so I keep the boosted mixture richer than the ECM wants to see?
I’m considering an additional injector controller instead of the AFPR, but the problem with the ECM is still the same.
Pro
Joined: Dec 2002
Posts: 704
Likes: 16
From: Dallas Texas
Re: Factory ECM, Blower & AFPR Question (Doug2500)
If you're running an OBD1 ecu, you have a wide open throttle (wot) table that has preset fi pulsewidths at given engine loads and rpms...the o2 sensors are affectively non functional in wot. to answer your question; yes, if you raise the static rail pressure you will feed more fuel in wot mode. Unfortuantely, that approach affects the cruise fuel table and the ecu will have to learn new fuel trims based on o2 readings. If the rail pressure changes are dramatic, it could result in a rich condition...the ecu cannot adjust for so much excessive fuel as the BLM parameters are pretty narrow. If you're wnating to do away with an fmu, you should get LT1-edit and a datalogging software (e.g., datamaster, etc.) and make some datalog runs at wot. Add fuel to the wot table until you either get the desired mix you want or you run out of fuel injector (80% duty cycle), which means bigger FIs and starting over.
Goodluck!
CT
Goodluck!
CT
