OK here's the deal. Most of the time the motor runs great. I drive about 15 miles on my average work day around town, and the problem occurs about 3 or 4 times, during that period. When I come to a stop, the idle get's real erratic. Twice, it's even stalled. If I shift to neutral, it still sputters. If I hit the gas, it hesitates for a sec, and then runs great. If I let it continue, after about 15 seconds, the computer kicks up the idle, and it runs fine. It does this cold or hot, rain or shine. I have a persistant check engine light, but have not yet pulled the codes. I know I know, I'm just real busy! O2 sensor maybe? Please help.

 

Oh yeah, I put a new stat in this weekend and all they had was a 160. I wanted the 180, but everyone seems to be runnin' the 160 so I thought I'd try. Like I said before, the problem didn't seem to be temp. sensitive, but It seemed to be worse since the new stat was put in. It may just be my imagination. And yes I had the check eng. light before I made the switch.

 

How hot does your engine get now with the new stat?
The stock chip is set for a 195 degree one i think. It doesn't seem like it, but if the engine doesn't reach the temp in which the computer is disigned to run then it will play mean games with your engine.
This may not be the problem, but worth a check. spend 5 bucks and try 180 or 190 in there and see what happens.
Did you clear the ecm for new stat? could help.
Hope you get it solved, there is nothing worse than a bad idle that is not cam-caused.

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'88 RS (originally 2.8)
New 350, .040 over, ported vette L98s, ported stock tpi.
Old 305 injectors & chip
TES headers, 3.73 gears, 700r4.
Best with 2.8-17.4@77mph
Best with 305-15.0@93mph
Best with 356-yet to race
(Damn the 2.8!)

 

It's more than likely running rich since you put such a cold thermostat in. That may not be your whole problem, but it sure doesn't help things either. It may not be going into closed loop operation anymore, and therefore your O2 sensor is doing no good. Has your gas mileage gone down significantly? If the car is mostly stock, take out the stat and get a 195 degree thermostat. With that problem out of the way, you can rule out things like the O2 sensor, MAP, CTS, TPS, IAC, plugs, wires, rotor, EGR....you get the picture.

 

Oh yeah, give us that trouble code too before you disconnect the battery and clear the ECM.

 

It could be your throttle position sensor,loose screws, or a internal malfunction in the tps .Instead of all this guess work U have to check the ecm for the code or U will end up buying a whole lot of sensors etc.
njdaewoo

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406 sb
dart 200 heads(out the box)
144 B&M blower
373 gears
Edl headers
3in cat back Flowmaster exh.
270 comp cams
12.50s @ 115mph
on street tires
60ft time 2.30
www.njdaewoo@excite.com
New Project car
86TPI trans Am
All stock for now

 

Yeah, I know I need the code. We're gettin' the scanner sunday. Fortunately, if we can't solve the problem sunday, I'll just leave it at my buddies shop until Monday! He's just the accountant, not a mechanic but he is a car guy!!! and he knows his stuff...