Thread: Stalls at idle until driven a while

I have a '93 SE-R stick with 215K miles. When I start it up cold it will idle fine for a few seconds then it will drop the idle until it dies. If I give it gas it won't die. If I drive it around for a few miles after it warms up it will finally idle fine and not die. But until that point I have to make sure to give it enough gas or it will drop in idle and eventually die. Keep in mind that it also does not feel like it is running at full power. The overall engine power feels lacking. Any thoughts? Thanks.

Additionally, when it finally idles where it should, the idle seems somewhat rough.

The FSM lays out scenarios of hard-starting when cold/hot...and are available online. It could be many things. Auxilary Air Control Valve? Air regulator?

Agreed, too many scenarios. MAF, TPS, other electrical bits could be at fault, bad grounding. Vacuum leaks, fouled plugs. 215k miles is a lot to troubleshoot without more information.

The Factory manuals are available in a few places to download, best bet is to start running through the procedures, eliminate what you can as causes, and see where that gets you.

Ok, here is an update and revised symptoms. It has a new alternator and new battery. I have removed, cleaned and tested both the idle control units (IACV and AAC?). I cleaned the MAF and it is already regrounded. I cleaned the throttle body a good while back and it looks clean still. I also removed and cleaned all ground wires I could find. Overall, the car runs well. It seems to have good power and no overall driveability issues. Here is what it is doing. When I start it up from cold, the RPMs will go up like they should then come back down to between 700-800 RPM just fine after a few minutes. With all accessories turned off, it acts just fine. I have around 14.3 volts at the battery and it drives and idles normal. I drove it a bunch like that and the idle pretty much stayed where it should be. The only issue is that if I turn the headlights on then the idle will drop down to under 500 and it will bog. It won't turn off, just bog. When it bogs down, the voltage at the battery reads in the low 12s. It will also do this if I turn on the AC. The thing is that it won't bog down every time. Sometimes the idle will compensate just fine and there is no issue. It is random. And that seems to be the only issue I am having at this point. I took it to Oreilly and had them test the alternator on the car and it tested ok.(the alternator is from Oreilly.) But it wasn't bogging at the time. I also tested the voltage at the alternator and at the battery and it was the same. While bogging down, I grabbed the wires at the alternator and moved them around and that made no difference. Any thoughts are greatly appreciated.

Hmmm. Turning on the headlights will put more of a load on the alternator, which will result in an increased load on the engine. Same with the AC compressor kicking in. The one thing that immediately pops into my head is that the belt may be too tight, and is binding under the increased load. Someone else may have another idea to check, but have a look at that first.

Sorry for the delay on an update. I tried loosening the alternator but that didn't help. But it think I have narrowed it down. When the engine is still cold it seems more sensitive to bogging down when I turn on either the headlights or AC. After warmed up here is mainly what it is doing:

At idle it will hold idle just fine. Once in a while it will bog down if I turn on either AC or headlights. But more often than not it will compensate pretty well.

Here is the main thing. With all accessories off, if I rev it to 3K and let off the gas it will come back down and idle just fine.

But, with AC or headlights ON and I rev it to 3K and let off the gas it will come back down and bog to around 400 rpm and slowly try to come back up to 750ish rpm. During that bogging down if I turn off the AC/headlights it will go right back to normal idle.
Any thoughts? And thanks so much.

Look to the FSM!

Diagnostic Procedure 37 - Engine Stalls when the Engine is Cold...EF & EC-169
*AAC, air regulator and circuits, injector and circuit, ign.coil, power transistor and circuits, spark plugs, FPR diaphragm, ECU harness, ECU pwr supply and GND circuit, ECU

Diagnostic Procedure 39 - Engine Stalls after Decelerating...EF & EC-173
*AAC and circuit, idle adj. screw clogging or TB clogging, injector and circuit, ign.coil, power transistor and circuits, FPR diaphragm, exhaust gas sensor, ECU harness, ECU pwr supply and GND circuit, ECU

Diagnostic Procedure 41 - Engine Stalls when the Electrical Load is Heavy...EF & EC-178 in my 1992 FSM.
*battery, alternator, injector and circuit, ign.coil, power transistor and circuits, FPR diaphragm, ECU harness, ECU pwr supply and GND circuit, ECU

...it is your friend!

Thank you so much. I have been searching but is the FSM on this site somewhere that I could download it?

does your alternator have a ground?