ion_four

So, I just started boosting, but after tweaking my fuel a bit (with a custom circuit, thanks to filetofit!) my car would fall on it's face at about 6-6500rpm...I couldn't find anything physically wrong, but then I looked at the output voltage of my MAP circuit and it was going above 2.9volts...so, when this happens and the stock MAP sensor sees boost and freaks out, does it dump a ton of fuel, or does it cut fuel? I'm just wondering how bad it is...

ion_four

Does anyone know what the ecu actually does when it sees boost? I'm not getting a check engine light, but I'm hitting 2.96+volts and my car is spazzing. it doesn't do it in first gear, sometimes, and I think it's because it's only for a split second, so the computer doesn't have time to freak-out.

Integra_Boi

i think i know what your talking bout... well i can get away with first and second gear with my check valves(bleeds boost from map sensor) but my third gear throws the check engine light off and to fix that problem... u either need a map sensor eliminator or missing link.. u could always get something lik e a J&S safeguard.. its for the mapsensor or a missing link which is a metal piece that is a one way check valve that bleeeds off the boost so that the map sensor wont find out your boosting.. what it does is.. it dumps a lot of fuel and makes you run rich.. so that you can drive home and get it checked out... and that will prevent detonation.. u should really get a air fuel guage first... thats the first guage u should get... before boost and other stuff... because you dont want to run lean.. i hope this helps you out or answered that question..

ion_four

thanks for the reply, but I have a MAP signal adjuster already (so I wouldn't need a limiter)...I'm not getting a CEL at all. In addition, I do have an air/fuel meter (actually 2 of them, as well as boost, egt and MAP voltage) but I can't get a really consistent reading because I have NO downpipe; the o2 sensor is just attached to the turbine outlet. I know I am rich because I can smell it, see it (the soot in the engine bay) and my car idles kinda rough (this changes when I turn the fuel down with my MAP circuit, so it's not a symptom)

after thinking for a while today I realized that it might be a vacuum leak. does this make sense? it isn't the BOV and I am able to peak at 6psi and hold it for a good 2000rpm stretch, but then it just completely falls on its face and the boost gauge shows a vacuum, not even just atmospheric (0psi)...any help would be GREATLY appreciated.

EDIT: when the boost drops, the a/f ratio is just as consistent as it was before...actually really rich because there's no boost. so, I don't think it's running lean. could it be too much fuel?


[Modified by ion_four, 3:12 AM 8/12/2002]

JM Performance

[QUOTE]because I have NO downpipeQUOTE]

uhh.......

Integra_Boi

yea get the downpipe done.. make sure u have ur o2 sensor in the right place first

ion_four

yeah, the turbo is just open under the hood...this is only because the place I brought it to said it couldn't be done with the AC in tact...so, I'll have to remove it. however, I don't think this is the answer to my prob. the O2 sensor would not cause this.