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I just put a new ECU into my 4g15 Colt , but it's running heinously rich now. It's a 1.5 5 speed GL model, the new ECU #'s are identical to the old ones.

The old ECU went bad, but before it did the car ran fine. There is no O2 sensor in the car, but that didn't seem to bother the old ECU (it re-learned after about 50 miles). I was hoping this one would do the same thing, but after over 200 miles, it is still running horribly.

Any ideas on why the car is running so rich? I have had to advance the timing as far as I can and adjust the idle screw nearly all the way in just to have it idle (somewhat) normally.

Driving it is also a bit tricky as you can't stay at a specific RPM long as the car will begin to lurch. It does accelerate albeit much more slowly, and I've had it to 70 MPH, blowing black smoke the whole way.

Any ideas?

Thanks and Aloha,

-Kev

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Cheap, Fast, Reliable......you can only pick <b>TWO</b>.

Probably the OLD ecu was failing it was just messed up runing rich is normal without an O2 sensor hey at least its better than running lean...

Yeah, I realize that some richness should be present....but this is ridiculous! Seems I'll be getting a new O2 sensor to see if that helps.

I do think it odd that the car registered no drop in performance when the O2 sensor went out using the previous ECU though.

-Kev

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Cheap, Fast, Reliable......you can only pick <b>TWO</b>.

What year is it?91-96 have bad mas wiring or something that causes it to burn out.I had a 92 that I replaced the ECU 4 times in a year and replaced the mas and had no more problems.

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Griffin FMIC,HKS 272s,1000cc RC injectors,T4 60-1,Rallyart O2 , ACT2600street disc,Z06/MAFT blowthru,3in.turbo back,Walbro 255lph, Crane Cams DI2 ignition. Now A COLT AWD
LilKnockMeter,digital knock meter gauge www.insaneimportperformance.com

I was considering the MAS as well, and I was thinking of just disconnecting the MAS altogether, but figured that would confuse the ECU even more and may result in a completely unstreetable car.

Anybody know where I can pick up a used MAF sensor for A LOT cheaper than $250.00??

-Kev

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Cheap, Fast, Reliable......you can only pick <b>TWO</b>.

Give me the # off your old one i can most likely get you one this weekend for around $45 CND + shipping.

Ricehunter: Thanks, I have to come up with the $$$ first. Getting head and manifold work done on my Talon, which is eating cash like a monster.

Just one thing: The Colt USED to get close to 35 mpg, but I went through a FULL TANK in 2 DAYS!!! I averaged 10.4 MPG....I might as well have a fricken SUV!!!

Would the MAF being blown cause it to run THAT rich? It's startin' to freak me out.

Aloha,

-Kev

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Cheap, Fast, Reliable......you can only pick <b>TWO</b>.

O2, Maf and ECU are about the only things that will make you run rich. Did you replace your O2? Even if your maf is toast i wouldn't think it should make your car run that rich, but maybe. Also have you checked your ECU caps?