1989 Calais Idle drops after 2 minutes.

[cujotom]

Hello All.

I am in need of assistance with some ongoing problems with my 1989 Olds Calais Vin D 2.3L4 MPFI. One of the problems that I have been running into is when you start the car. In the first 2 or 3 minutes the idle on the vehicle will drop to below 400rpm. It is just about at the stalling stage, but it wont. You can throttle the accelerator but there is no response. The idle will come back to normal by itself within a minute or so. This only happens at start up. Cold or Warm makes no diffrence. And it only lasts for that couple of minutes. Here is what I have found out thus far. For starters the ignition module was just replaced as in testing it the high idle on it was bad. The crank sensor was also replaced. One of the coils was supposedly replaced. But when I tested them with my meter they were both in spec. The housing has some carbon tracking on it. But that is normal for this car. You can wipe this away with your finger. All the usual tune up things were done. Plugs, Plug boots , fuel filter, new oil air seperator, air filter, etc. Heres where it gets interesting. In hooking up my fuel gauge to the regualtor, I am getting an unsteady reading. The needle will jump from about 34psi to about 42 psi./ The needle only is steady when you unhook the vac line off the regulator. When you pinch the return line it goes up past 60psi, (Which is normal). The unsteady reading is just about within spec. But I believe the needle shouldnt be fluctuating like that. My first guess would be Fuel pressure regulator. Now in looking at my scantool readings. When the cars idle first drops, you can watch the integrator numbers drop into the 30s. (Normal being as close to 128 as possible) Which would show a lean condition. As soon as the idle starts to come back up so does the integrator. This afternoon I scanned it. The integrator only made it back up to 83. (still on the lean side). I am scanning the vehicle in closed loop, with a temp of 178 Degrees. My injection pulse width is around 1.7ms. Now... Since this would show a lean condition. Why do I smell a rich exhaust? Here is the other problem I am looking at. GM put out a TSB on this vehicles coils. They had major problems with them. The mechanic claims he changed one of them. The TSB says to change both of them. Now remember earlier I said I had metered them at spec. The issue here is a spark advance reading at anywhere between 12-28 degrees! Its all over the place in that range! (At idle). This is my train of thought. Its either the fuel pressure reg. Or, the coils. Or both Lol. In addition, I have a brand new battery. I cleaned the fuel injectors (With the canister) And decarbonized the insides with Motorvac cleaner. The worst part of it all that this problem only happens for a minute. After that the car is running fine. I have checked for vac leaks. None. The TPS changes smoothly.The iac cycles open and closed at spec. The Map sensor tests at spec. I am running out of breath here! Lol. Any educated guesses out there. Would you go with the Fuel pressure reg, or, the coils, or something diffrent... Any help would be breatly appreciated. Tom

[malletslinger]

Originally Posted by cujotom

The issue here is a spark advance reading at anywhere between 12-28 degrees! Its all over the place in that range! (At idle).

Do you mean that when checking the timming, that the reading doesn't stay constant, but jumps around?
If that is what you mean, then your answer is in two words...TIMING CHAIN

That is normal wear and tear. Replacing your timing chain, sprockets, and tensioner/guide will fix this unsteady timing reading...among other things.

You could probably do it yourself with if you have the right tools and a Haynes Manual(or a guide of some kind) and you can pick up the parts for like $50...or you can pay a mechanic around $300 to do it for you.
If there is space infront of your engine for you to get your arms in there and you feel confident, then you should be able to handle it.

[cujotom]

I meant when I checked the readings off the scantool that spark advance was all over the place (12-28 degrees) within that range. Are you still leaning towards timing belt?

[malletslinger]

By scantool you mean timing light, right?
If you check the timing in open-loop with a timing light and its all over the place, then you need to replace the timing chain.
If you are using a different scantool, tell me/explane to me what it is so I can tell you if the diagnosis is the same.

[cujotom]

No. Not a timing light. A scan tool. You know OBD1. Scan your engine parameters. Auto XRay, Actron, Genisys, Tech 1, Tech 2, etc. Thats okay. I think I figured this out. Thanks Anyway. Timing Chain. Okay.....
Tom