I have done TONs of work on the 89 car. New intake refresh. New ignition all around. But the car still runs weird from cold until after 170•F warm. At full temp the car runs awesome. But during the first 10 minutes or so, it stalls multiple times or randomly revs up to 1700 rpm for 10 seconds then back down. Seems like fuel or idol valve issues? It's all very strange. What could this be? MAF? Bad sensors on the water neck? Bad O2 sensor? (O2 sensor is only 3 years old with 30K miles... who's to say it's not bad though)

Who has experienced this and where should I start so I'm not just doing random with new parts.

I"m going to start with sensor readings at cold and hot.

 

To start..did you verify the TPS is installed correctly and sends a idle signal (hear a ´click' when you release the throttle mechanism)? Did you verify that you don't a have a vacuum leak?

 

when the intake was refreshed were the ISV, injectors or MAF replaced?

whats the status of th LH computer?

 

The sensor that I would start with is the Temp II, esp, since you replaced the 02.

 

I'm interested in this thread. I also have the same issue with mine, replaced the 02 sensor and the temp2 sensor along with the connector as the wiring was a little crispy but it did not resolve my problem.

 

MAF is who knows how old. I doubt its that since the car runs very strong at full temp. ISV is what? TPS, where is that? Don't know where those are. How can I test the LH and where? I doubt it's injectors or LH. They work or not, so the car would run poor at full temp too with bad injectors. Crank trigger is also new. No change. I doubt it's a vacuum leak. All intake lines are totally new with refresh. The car idols smooth and strong after hot. It's just some strange random engine cut off during cold.

I'm thinking I should have Bill Ball from the next town come over with his 89 and we can swap a couple items and see what happens..

It seems like fuel just shuts off. Then when I restart the car it fires up no problem.

 

That sounds like the TPS wasn't installed right, but a sticky idle control valve as well.

Go out to your car while the engine is off, and open the throttle using the linkage. Do you hear an audible click as you put your ear close to the intake manifold?

 

All of the components related to the fuel injection system can and will cause intermittent issues......the MAF and LH do wear out slowly resulting in a variety of issues as does the fuel pump. If all these components are vintage 89 they are suspect.

ISV is the idle stability valve located under the intake on the throttle body normally replaced during the intake refresh due to the work required to access. The throttle position sensor (TPS) is in a similar location.

 

Here is my intake before refresh. The first photo shows the ISV (located in middle of photo, two black hoses going into it). The second Photo shows the TPS (little black box at top left of Photo)

 

Ok, this is very helpful. Yes, I recall seeing these items when I replaced all the vacuum lines in the intake area. No they ICF and TPS were NOT replaced. That may be a good start. It think I can reach them if I pull the MAF. My hands are thin.

 

and after

 

The only way you are getting the IMS out is removing the intake and then removing the bottom half (silver part on the after refresh pic)...there are two bolts holding the IMS to the intake.

 

Very nicely done!

 

Please post more pics of the process. I'm interested in the vacuum lines between the throttle body and intake. Good job, can't wait to get mine done. What has the performance result been after installing the refreshed intake?

 

Do a search here and you will find a great diagram of all those lines...if i come across it i'll post it.