BPT: Problem help!!!

[94mx3rsr]

Hi, I live in Canada and own a 94 mx3 with a bpt GTX engine...I've had it for almost a year now and it is running great after 20 000kms with it.

However like many people i decided to up the boost and have been getting a strange phenonmenon happening.....

On highway pulls my car tends to lean out when I jump from low rev and vacuum to boost conditions over 10-11lbs...my air fuel meter seems to indicate full green when i floor it until it comes back slightly and then jumps to red.....

My fuel pump was upgraded since with an rx7 turbo II fuel pump and things havent really changed that much....i used to reach a sort of fuel/boost cut at around 14-15 lbs when it started to lean out whereas now i hit it at 11-12 (since I got a 2.5 inch exhaust)

The thing is ....when I floor it on a continuous acceleration 1-2-3-4-5 (gears) I do not lean out and I stay in full green according to the air/fuel meter all the time or if I start out in fourth or fifth and gradually go up the rev and boost and then floor it I have no problem staying in the green all the way.....it seems like the transition from vacuum to boost is a problem even though car still seems to accelerate normally

I am running BP55 euro spec GTX mapping a protege or familia N/A 1.8 SOHC air flow meter.....I have also used the strainer from my other pump on my new one which was fitted exactly the same way....

Did anyone here experience this and what could be the cause????

thank in advance

Jean Michel
Quebec, Canada

<small>[ February 27, 2004, 07:26 AM: Message edited by: 94mx3rsr ]</small>

[94mx3rsr]

The car leans out mainly under wide open throttle....but the other day it leaned out while I wasnt completely at WOT (maybe 90%).........

The car leans out (according to the air fuel meter) and then reaches fuel cut (which most GTX guys know how it feels)....As boost goes up the car leans out even more and reaches fuel cut more quickly..

I installed a 2.5 inch totally free flow exhaust about a week ago and the problem has gotten worst the car seems to lean out at lower boost than before (about 11-11.5lbs at WOT) (@ 13lbs it needs about 90% throttle to lean out)... Like before it seems to lean out most when I run it from vacuum to boost at WOT

When I step on the throttle...the air/fuel guage indicates full green..stay there for a while and then suddenly flips to red and usually I get the fuel cut....

I tried another protege air flow meter today just for fun and I still have the same problem....take into account that since my air flow meter is from a protege...it is just slightly smaller than a gtx air flow meter...

thanks for the help!!!!!!!

Jean Michel Basque
Quebec, Canada

<small>[ February 27, 2004, 07:08 AM: Message edited by: 94mx3rsr ]</small>