slipbakka

Hello everyone i need help on this problem i have.this post might be long.but ever since i joined this club the help i received has always help me and saved me money. so here i go i have a 1987 cutlass supreme 2 door with a 231 engine.i recently brought a jet performance chip stage 2 chip from a auto store that is going out of business.the chip was $50.00 so i brought it the box say the chip is for a 1984 231 engine cutlass supreme.is there a diffrence between the 84 and 87 231 engines.because i install the chip and my check engine light came on and the smell from the exhaust is the car is burning to rich with a light black smoke coming from the exhaust pipe.i ran the check engine code and the code flashed code 15 which it said the coolant sensor is stuck open.i changed coolant sensor and changed oxgen sensor.the light is still on i tryed calling jet performance but the phone # is long distance and they put you on hold to long.i need to know do my carburetor needs rebuilding or should i retard the timing with a timing gun. plus the car idle is a little low like the car wants to stall but it doesnt.please help anyone p.s. i changed the thermostat from 195 degrees to a 160 degree thermostat.please help..plus the chip was brand new still seal in the rapper.

Olds64

Your computer could be saying that your coolant sensor is stuck open since you put in a different thermostat. Why did you change the thermostat in the first place?

Since you put in a new chip, your car has probably changed the air fuel mixture. If your car starts running rich then your O2 sensor will pick up too many hydrocarbons in the exhaust and lean out the mixture. This will cause your car to run poorly and it might even start to miss. If it starts to miss then you will have even more HC in your exhaust and it will become a vicious cycle.

Give your car some time. Since it is an early GM type I computer it might take it awhile to learn. Then again, let us know if there are any more codes in your computer.

Ultimately, if you really want some power then drop the 231 and find a 350 to put into to your car.

slipbakka

I changed the thermostat because jet performance web site said to use the stage 2 chip you need to change the thermostat to a cooler one the 195 degree is too hot they recommend the 160 degree thermostat.

88 coupe

I would think so, since they do not show one for your application.

http://www.jetchip.com/products.asp?...&model=576#576

Norm

88 coupe

For a different application?

That would be a whole different discussion, again.

Norm

Olds64

I was thinking about your problem the other day and the new thermostat is probably related to your problem. Computer controlled cars run in two different modes, open and closed loop. When the car is started it runs in open loop using all of the sensors to set air fuel mixture. After a certain point the car enters closed loop operation and only uses the O2 sensor, the throttle position sensor, and the ECM to set air fuel mixture. The car enters closed loop once the coolant temp sensor reaches a certain point. Your coolant might not be getting hot enough to let your car enter closed loop operation.

You need to PM Oldsguy and have him ask his buddy on HAMB about this problem. He has a friend that teaches at a Vo-Tech school. He would be able to lead you in the right direction.

slipbakka

Thanks Olds64 for the good info. You are always there to help..

88 coupe

He has a "performance" chip that does not match his computer.

The mfr recommended a 160° stat, on the assumption, he was using the correct chip for that application.

First step, would be to re install the stock chip. If the problem were to go away, we could conclude, the chip is the problem.

Norm