So do you feel it is getting to much fuel on cold starts now? I was thinking you where saying it was not getting enough.

Since you said you had to step on the gas a little to make it start better that should cause the injectors to output more gas even though it is more air also.

Sorry, I wasn't quite clear. Cold starts now exhibit the same symptom my warm starts used to. That is, it seems to be flooding now. If I put the pedal to the floor and crank, it cranks a couple times and fires right up. If I don't it cranks forever and sputters to life.

Man! the fun never ends does it...

Do you think the thermo switch for the cold start could be stuck and it runs fuel whenever you crank the engine?

Have you tried pulling the plug on the cold start to see what affect it might have?

Have you checked the temp the ecm is reading to see if it jives with the real temp?

CSI could be involved, but again, why would I start getting cold start problems after replacing a bad thermo switch. That's what I just don't get.

I guess if the CSI switch is bad, it could cause it to run rich all the time. "All the time" would include right up until I shut it down. Then on cold start, it's effectively already primed, and the CSI shoots still more in there, and floods it.

I'll track down the plug for the CSI and leave it off and see what happens. It still smells a bit rich to me, but definitely better than before, and it sure runs better.

I don't have the ability to check the temp the ECM is reading - don't have the tools. And I have a feeling my Fiero budget's gonna get audited soon, so investing in more tools is not a wise move at this point.

[This message has been edited by WhiteFormula (edited 04-27-2006).]

Well, I replaced my coolant temp sensor and voila. Just like White Formula my engine now idles much smoother and the rich smell has just about disappeared even without a convertor on the engine! They sure buried that sensor out of sight, but it was not too hard to change. No more gas masks!

WhiteFormula
Unless someone altered some wiring (is that a possibility?) the CSI is powered off the starter relay power so there is no way it would run except when cranking the engine.

2nd. If you have a pc, all you would need is a cable and you could at least check you ecm around the garage. You can make a cable for less than $10.

[This message has been edited by Dodgerunner (edited 04-27-2006).]

The wiring looks un-tampered-with, so it's probably wired correctly.

Thinking about this logically, the replacement of the temp sensor must have uncovered another problem. At one point I had adjusted the idle screw, so I'll take another look at that (didn't adjust it much, but it was a long time ago, so it's worth checking). I could grab the TPS sensor off my brother's GT to test that, and outside of those things, the only items left to check/replace would be injectors. Don't have the funds for that at this point ($400?).

As for the cable, proud Mac user here. I could probably cobble together a PC though...

Maybe possible that the TPS could tell the ecm the throttle was open more than it was and move up in the fuel table even though the throttle blade was not open very far.

Never suppose to touch the idle screw. But that usually causes idle problems.

Think your right though you fixed one problem that was covering up another..

Here is a post that has some links to setting you screw back...
https://www.fiero.nl/forum/Forum2/HTML/071340.html

[This message has been edited by Dodgerunner (edited 04-27-2006).]

White Formula,

If you reset your idle and still have starting problems you might look the cold start injector. My car would flood on cold mornings. When it was removed, I saw that it appeared to be leaking. My exhaust smell was reduced after I replaced it too. You can change it by pulling the distributor only, no need to pull the plenum. Changing the coolant temp sensor really made a difference in the idle of my car as well. Thanks for the tip.

Rick

[This message has been edited by Rick 88 (edited 04-28-2006).]

So I went outside this morning and decided to reset the idle screw. My thought was that since the IAC valve is supposed to handle airflow at idle, I ought to back the screw off enough to close the butterfly, but not so much as to let it slam against the bore - that is, let it rest on the screw while still being closed.

That thread confirmed my thoughts.

Turned the key, fired right up. Excellent.

I let it idle a bit, and trying to start it once warm appears to be an issue. Cranks a lot, then sputters to life. Back to where we were before replacing the temp sensor (albeit with less stink and better idle). :/

I've got a new O2 sensor sitting on the shelf, so it looks like that's the next part that'll go in. What compound is recommended for the threads on it, BTW?

Thanks all for walking me through the diagnosis. Hopefully others can benefit from lessons learned here.

[This message has been edited by WhiteFormula (edited 04-28-2006).]

I just put some anti seize on the threads and installed it.

Dito the high temp anti seize.

I don't know if I believe the talk, but some say you need to reset the ecm and let it relearn the idle.
Could try it, but don't put much stock in it...

New O2 sensor installed. No change.

Incidentally, the Bosch O2 sensor I put in already had anti-seize compound on it.

At this point, it seems that everything I can think of to resolve the warm start problem has been replaced with the exception of the injectors and cold start injector. Seems to me that one or more of them have to be bad.