Strange starting problem on 99 ga 4cyl

I have a 99 GA with almost 100,000 miles on it. I am having a problem starting it. In the morning when it is cold, it starts up pretty fast, then idles rough for 20-30 seconds, then smooths out. After it's been driven and the engine has been warm, it won't start without giving it gas and it cranks for a long time. So it starts best when it's cold but still doesn't start well. Once it gets started and the idle has smoothed out, it runs great, hot or cold. Here is a list of what I've done trying to fix the problem, as well as normal maintenance.

New fuel filter
TPS
Map sensor
cleaned throttle body
run fuel injector cleaner many times
new air filter
new plugs and wires (or whatever you call those stubby things)
Battery

Does anyone have an idea what might be causing this problem? It's just a problem starting. While I'm driving, it performs just fine. No shudder, hesitation, stalling, rough idle or anything.

Oh, one more thing. When it is really cold outside and I start it, it never idles high like every other vehicle I've driven. No matter what the outside temperature, it runs at low idle after it is started.

I would say your idle air control valve -IAC is pluged or bad.

The IAC regulates the air by passing the Throtle body(TB) by moving its pintal in and out of the passage way. If this is even partially pluged it can effect Idle.
The IAC is controled by the PCM, adjusting idle speed depending on running conditions , AC, powersteering, cold or warm. Other wise Idle is not adjustable.

If you dont know, the IAC is on the TB . Should be facing forward of car on your 4cyl.

To test the IAC.
When the engines cold the IAC should increase the idle and vary as it warms up.
With the engine warmed up and place a load on the engine by turning on hte AC or turn the steering wheel. The idle should remain steady or increase a little.
If it stalls or stubles then the IAC is not working proprly.

Shut the engine off, disconnect the electrical connector from the iAC.
the terminals are # left to right.
[1][2]
[3][4]

Using an Ohm metter test the resistance acrossed terminals 1-2, then measure acrossed 3-4.
The readings should be about the same on both sides. If one of them show an open circuit replace the IAC.

If the IAC checks ok, it could be your PCM which a dealer will hav to check.

Something to try is removing the IAC and cleaning the port/opening with TB cleaner and try and remove any chunks of carbon.
Try not to let the crap go inside the intake.

DO NOT push or turn the pointy tip of the IAC. IT will mess up the calibration.

Thanks for the help xeroinfinity. I'll give that a shot tonight and see what happens.

Keep me posted !

I haven't had a chance to look at the IAC yet, but there is one more thing I wanted to mention. On the rare occasion that it does start without me pressing the gas pedal, I smell a lot of gas after it starts. It almost seems like it may be flooding, or else not firing. When it does start on it's own, I smell a lot of gas, it runs really rough, then after about 30 seconds or so it smooths out.

Test and or clean your IAC, that should clear up the starting issues.
As for the gas smell, its just flooding its self when you are trying to start the engine.
Another thing to look at would be your injectors, the rubber "O" rings that seal them from leaking my be dried out and leting fuel escape.

I'll give that a shot. Thanks! Hopefully I can work on it this weekend.

I sometimes too smell a few fumes of gas or something from the exhaust when I start up cold (not ran all day) :dunno: .. it shortly goes away though

Well, I changed the IAC and it didn't help the starting problem. Any other ideas?

Did you clean the port that the IAC resides in ?
ALong with the passage that goes to the intake/TB ?

Yes, It is perfectly clean where valve plugs the hole by the butterfly, but I didn't do anything with the passage that runs off to the side. Is that where you're talking about.

Yes, It is perfectly clean where valve plugs the hole by the butterfly, but I didn't do anything with the passage that runs off to the side. Is that where you're talking about.

Yes the passage that runs through the TB into the intake.
If its not open or obstructed, then it doesnt work right.
Thats how it controls the idle.

You might have to scrape it out, becarefull not to gouge the intake or TB to much :eek:
Try and remove all the big chunks, not letting them drop into the intake.
Wont hurt if a little gets in, but big chunks :nono:

Well, that wasn't the problem. The passage that runs into the intake was very clean. A little carbon color, but zero buildup. So it looks like that rules out the IAC as the problem. Any other ideas?

The only other thing is maybe your injectors are dirty,
or maybe you hav a small vacum leak.

You also could hav low fuel pressure :dunno:
You'll hav to rent or buy the tool to test that.

Keep running injector cleaner through the system and maybe that'll clear it up.

You'll probly just hav to deal with it for a while.

Good Luck

I was wondering about fuel pressure, but should I smell so much gas when I start the car if fuel pressure is a problem? I want to test it either way. What should the fuel pressure be? I'm going to start running fuel injector cleaner in the meantime. I have run a lot through it already, with no noticeable improvement.

I you smell gas realy strong when your starting it your injectors O rings are probly leaking.
That could be your prob, letting air in till it warms up.

Fuel pressure is 41-47 psi.

Might see about getting the injectors cleaned by a professional , or replaceing them.
They are pricey about $95-100 each, you can find them in sets for much less just shop the Net.

The throttle blades will carbon up and cause erratic idle conditions. Just get some carb cleaner and clean the black residue off them. ALso, have you checked your fuel presurre on start up? The fuel pressure regulator may be crapping out.

Did you all ever figure out what the problem was? I have 95 with a 2.3 engine that does the very same thing and I did all the same things to try to fix it. When it first starts it runs fine then about 20-30 second it basically trys to flood itself unless you can step down on the gas a few times. If you do that it comes out of it and does not do it again. I also notice at that point the temp gauge is just starting to move also. Should it be storing any trouble codes on a cold engine?
Any help or further ideas and how to test them would be greatly appreciated!

IF thiers codes they'll be there not matter if the cars hot or cold. The most DTC's only go away when cleared.

The fuel pressure regulator may very well be the problem as crazy_jim stated above.
With the 4cyl you need to rent or buy the Fuel pressure gauge and its adapter. It needs to be installed in the fuel lines because the 4cyl does not have a test port like the V6.

When the fuel pressure regulator went bad on my '02 3800 it had starting issues similar to what is being described in this thread. 60U$ corrected the problem...