Check Engine Light

[alanw6]

I just put a v-2 sq s-trim on my otherwise stock 92 LX 5.0. I've been very impressed with the improvement. :D

Have a question for you guys:

When the car is pulling hard after about 4500 rpm, the check engine light will illuminate until I shift or let off.

Am I overloading the stock MAF voltage? If so, will a larger MAF calibrated for my 19# injectors solve the problem?

Thanks in advance,

Alan

[blown89stang]

It's very possible. You really want to run bigger injectors. How much boost are you getting? Still it doesn't matter, go with some 24#-30# injectors and have your MAF recalibrated. Go to mustangworks and go to there" Analyzer"and you can run your setup and plug your numbers in and it will tell you what size injectors you should be using. www.mustangworks.com

[MoDo]

run the code, you could be getting a "rich" or "lean" code from the o2 sensors

[Forcedpower]

Originally posted by MoDo
run the code, you could be getting a "rich" or "lean" code from the o2 sensors

Your o2's don't work at WOT. Or do they and I'm thinking wrong? I always thought they did nothing.

[MoDo]

you are correct but if he is dumping a lot of fuel they can still give a rich condition

[alanw6]

Thanks for the helpful replies.

That analyzer tool was pretty cool, and it suggested I goto at least 24# injectors.

If I am indeed tripping a "lean" code at WOT, how concerned should I be about this? The light is on for only a second or two at the most.

This is a street car, completely. ETs are not my primary concern, reliability and the power to dust off unsuspecting people in traffic was the reason for my blower.

Thanks again for the good advice,

Alan

[VibrantRed94GT]

Not that i can help, but i am having the same exact problem..
Check engine light comes on for a couple seconds after i get into it hard, then it just goes right out... when i scanned for codes i only get codes 311-314. which is smog pump related (removed the smog pump)... so im not sure of the problem.. but i am running 19lb injectors, 12:1FMU, 9lbs boost. on stock motor.

[alanw6]

Vibrant,

That is HIGHLY interesting post you wrote. You may want to look at my other post: Smog pump = KABOOM to see what has happened since I wrote this one.

Check engine light came on with hard acceleration, and smog pump failed about 20 miles into life with the new blower.

It is locked up as tight as can be, and will be replaced this weekend.

I thought about bypassing the smog pump, but can't justify the risks (cat damage, etc) versus the benefit (.5-2 HP).

Check that smog pump, when it goes it is loud, smoky, and pretty damn exciting. Not to mention embarassing when it happens as you are pulling away from a Z06.

Alan

[Forcedpower]

On 93 down cars the smog pump won't trip the light. The computer isn't hooked to it in any way no sensors. I don't even have a smog pump on my car and I get no codes.

[dmpmw]

Check for vacuum leaks around the intake, and air leaks around the discharge tube.

Mike

[VibrantRed94GT]

my cars a 94 GT.. i havent had the smog pump for a year now.
The codes that get me are 177 and 173 which indicate the O2's are reading a rich condition.. I am running with a 12:1 FMU, 19lb injectors, walbro gss340 pump, 10lbs boost and no detonation whatsoever.. 52psi idle presure (vacuum attached) and 85-90psi WOT... I am getting a momentary engine check light under boost.. then a few seconds after i let off, the light goes out.. I just dont know why the base presure is soo high. And the adjustable regulator dont seem to turn it down any. Maybe a restriction in the return line? or a bad reg? Im lost!!

[alanw6]

Does anyone know anything about "pegging" the MAF, and if this would cause the check engine light?

Also, I won't need more than 32 pound injectors when I change to larger MAF for an s-trim and otherwise mostly stock 92 LX?

Exhaust from headers all the way back is about the only other major thing i'll do.

Oh yeah, and BRAKES!!!

Thanks for all the feedback so far.

Alan

[VibrantRed94GT]

i think u meant 36lb injectors... i would say thats plenty injector for a mostly stock motor otherwise.. it will need to be tuned to run those injectors though.