It does this every time I go wot or when it shifts gears. Is this a rich condition, or a valve problem?

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"Why StockBastard?" you might ask. Well...
84 Berlinetta body w/custom paint.
92 front/rear bumper and ground affects.
89 IROC 350tpi engine w/lots of mods.
87 3.73 possi rear w/disk brakes.
86 interior w/IROC dash.
And finally, stock Vet rims from the early 70s.(same ones used on the 69ss)
ALL IN ONE CAR!!!

 

yes, a rich condition. the motor is getting way too much fuel for some reason....check it out

 

I agree and you might want to check your oxygen sensor if it is doing this under part throttle. I would think if the oxygen sensor is operating correctly it would compensate for rich under part throttle conditions.

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87 Iroc 5.7, AFR190, SLP Cam(218/224), SLP 1 5/8 headers & cat back, Random CAT, SLP Runners (matched intake-runners-plenum), 48mm TB, 6E(arap) chip, Vigilante & Probuilt trans.

 

O2 sensor does nothing when in WOT (PE Mode). Your engine has too much fuel going to the engine when in WOT.

Things that can cause this are:
1) Too cool of a T-stat or a misfunctioning CTS
2) A relocated MAT without proper compensation in the eprom
3) Too high of fuel pressure.
4) A mismatched eprom for your engine mods.
4) A restriction in the intake.

 

I know O2 has nothing to do with WOT. The initial post comment was WOT or when it shifts. I was referring to the "when it shifts part" and assuming he was referring to under part throttle in that scenario. Anyway.....

 

It depends on the eprom, but you do not need to be at 100% TPS to be in PE. Generally somewhere around 70% is all that is needed.

I don't think he is talking about light/part-throttle but WOT or heavy/part-throttle which would remain in PE.

Anyways, he's got a few things to look at now.

 

WOW, thanks for all the ideas. I suspect it's either the fuel pressure or eprom. I've done several mods, including headers and full exhaust, without upgrading it. However, it is an aftermarket. Hypertech,I think.

------------------
"Why StockBastard?" you might ask. Well...
84 Berlinetta body w/custom paint.
92 front/rear bumper and ground affects.
89 IROC 350tpi engine w/lots of mods.
87 3.73 possi rear w/disk brakes.
86 interior w/IROC dash.
And finally, stock Vet rims from the early 70s.(same ones used on the 69ss)
ALL IN ONE CAR!!!

 

Say what now?? A bad CTS can make black smoke?? I sometimes have puffs in between shifts..I think my CTS is gone too.I have a terrible time with my car idleing for the first 8 seconds or so when the car is cold..I am sure it's gotta be th CTS..but I didn't know it cold affect the car once it's warm..

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• Red '88 IROC 5 Speed 305 TPI w/3.08
• Dual Friction Stage III Centerforce Clutch
• Accel 300+ Racing Ignition
• Accel 300+ Pro Sleeve Plug Wires
• AC Delco Rapid Fire Plugs
• Flowmaster Force II 3 Chamber Cat Back Exhaust
• Hypertech Chip
• Hypertech Airfoil
• Gutted Air Box
• Best Maryland (40 degrees) E/T 14.686, 60' 2.205, 1/8th mile 9.461, 1/4 mile MPH 93.91
• Best Florida (80 degrees) E/T 14.88, 60' 2.163, 1/8th mile 9.540, 1/4 mile MPH 92.74
• Best 60' 2.163(Florida)
• TPiS AFPR set to 42psi using Accel Fuel Pressure Gauge (Installed after Maryland run)
• Aluminum Driveshaft (Installed after Maryland run)

 

The CTS is one of the most important sensors in the engine. It is the sensor that tells your engine that it has attained closed loop, how warm it is (for idling), controls block learn and a ton of other things that check the CTS to determine whether they should operate and control the mixture and spark.

If your CTS is bad, if it DOES attain closed loop status, it could run too rich as the engine still thinks it is "warm up" mode.

As for that Hypertech chip, they honestly don't do too much; a little extra fuel and spark thats about it. But the problem is the GM stock eprom is too rich as it is. I basically have the same mods as Stock is discussing and I was 15-20% too rich in my fuel tables. And that is with my fuel pressure adjusted to as low as it could go.

 

That's another thing. I have an adjustable fuel pressure regulator and that sucker is turned up to like 45 or 50. My car idles fine. Starts on the first crank too, and it runs like a banchee (killed an lt1 yesterday, should have seen that kid sobbing at the next light but that smoke really bothers me. It rattles very slightly at WOT too. I have just recently been using 88 octain. I suppose that could affect it.

thanks again.