runs rough and idle too, help please

[PC5505]

Searched FAQ's a ton and couldn't find anyone with this situation...

Not a Noob, this is my 3rd eclipse and still have a 95gst in the driveway.
I have a 91 mitsu GSX manual with 171k miles, which has been driving fine the 4 months I've had it, except that when I start it up cold I have to let it heat up about 2 minutes or when i give it gas it dies. After its warm its fine, quick and reliable. Also it seems to eat gas a little quickly.
I noticed that it doesnt start at higher rpms like it should when cold, it just starts and idles at 800. If I get on the gas very slowly it stays running but any more and it dies unless I let it warm. If I give it some gas while its cold and then let off too quickly the rpms fall below idle speed and it would die.
Last week I found a leak in the top of the radiator while on a very short trip, i patched it and checked the coolant level and it seemed fine. When I started it again it idled very rough and stayed rough even under throttle. It will drive but it wants to stall when stopped.
I've also noticed that I can smell unburned gasoline in the exhaust now, haven't noticed if it goes away under throttle....
The car is modified with a number of bolt on parts including an evo3 turbo w/ upgraded flapper limited to 15psi by a TurboXS manual boost controller, has a K&N intake, crushed blow off valve, rewired fuel pump with 12-gauge wire, ported evo3 exhaust manifold, 2.5" downpipe, high flow cat, and 3" exhaust from downpipe on and a 2500lb clutch, A/C is disconnected. None of these mods have caused any problems for me in the past so barring any complications from these, I was wondering what you guys would make of these symptoms... I was thinking it might be the idle control motor and since its never shown a check engine light(supposedly they don't when they go wrong) and I hear it's a common failure on DSM's but I didn't think that would affect it while under throttle and it doesnt explain the unburned gasoline smell in the exhaust. Also I'm not sure why it would affect cold starts so much...possibly a temp sensor(also)?
Any suggestions would be much appreciated,
-thank you

 

[kidwiththelaser]

http://www.geocities.com/MotorCity/Downs/7678/dsmtests.html

Id check the main electronics that tend to go bad, the isc, the engine coolant sensor, the cas. Check those first, and then if they check out then come back for help. And if one of those fix your problem then let us know!

I check the CAS, by disconnecting it, turning the key to the on position, and then spinning it manually. You should hear the EFI relay kick in, and you should also hear the injectors ticking. If you dont hear anything, then check the voltage going to it. If there is voltage suspect a bad cas, if not suspect a bad ECU.

hope this helps!

 

[Cool Mr Steve]

You may want to check out your ECT (engine coolant temp sensor). Generally, when your car starts it first uses the ECT to check out if your engine is warm or cold. If it's cold, it waits until it's warm to go into its closed loop fuel mode where it uses other sensors to control idle and such. If it is malfunctioning it may never go into closed loop or may be constantly in closed loop (i'm not sure if there is only one specific way that they malfunction, but it's worth a shot). As far as your problem goes, though, it almost sounds like your car is constantly in closed loop, where it thinks your car is warm when its cool. Of course, it could also be your FIAV (Fast Idle Air Valve).

As far as smelling unburnt fuel and having bad fuel economy, there is a number of different things that it could be. To start you off, though, you may want to get your o2 sensor tested.

 

[kevint427]

Yes, the infamous "rough idle/wants to die." MY CAR DID THE SAME THING! I hated it! Made me angry for weeks. Untill it threw a CE light. Swapped out most of the emissions crap. EGR valve and piston, ISC, FIAV, that kind of stuff plus some. Idled beautifully. Make sure you didnt blow a boost/vacuum line. Keep thinkin' and the problem will be fixed soon!

 

[PC5505]

Okay, so I put in a new thermostat and coolant temp sensor, swapped plugs, kept the old wires, they're aftermarket and quite a bit thicker than stock. Got an idle control motor out of a junk yard (15 bucks), checked the o-ring and its in good shape so I kept it. Tested the old motor with a multimeter and a couple pairs of the terminals read 0 ohms of resistance (should be 28-33) so i know that's bad. Problem is I checked the new one and terminals 2 & 3 are not showing any resistance either, it supposedly came off a running engine so I'm a little pissed about that, oh well, only 15 bucks.
Not really convinced the idle motor is the only problem, but its not too hard to swap, so I did just to see if there was a difference, and there wasn't any. Though I could hear the motor run a little as the the engine was shut off so i know its at least trying to do something.
Just for my own amusement i ran the engine with the motor unplugged and still no difference. Think I'm going bite the bullet and order a rebuilt IAC off the net and see if that does it, they want a hundred bucks, let me know if anyone knows a cheaper supplier....gonna have to wait till at least monday, no one works sunday. Still need to check the O2 sensor and the fast idle air valve, but napa and shucks were out of stock on both. Hope I dont need a new ECU as I've been informed that they can be the culprit, mine already has the upgraded capacitors. Running out of ideas. Trying to fix the cheap stuff first, but getting frustrated.
And just to top my weekend off my 95 gst decided to throw a check engine light last night and i havent had a chance to do more than a cursory look under the hood for leaks, fluid levels and burst hoses(all ok) at least it still drives okay.
Damn DSMs cant live with 'em, can't smoke a vette on a budget without 'em.

 

[PC5505]

Fixed!!!!........mostly.
Found a guy parting out a 2G and got his IAC for 10 bones, got real lucky, it was a revised IAC. The originals were going bad so often mitsu had to revisit the design. If you're lookin for one, they're black and plastic as opposed to the original which is metal and has a kind of peach colored top. I highly recommend the revised one because its a few years newer and much more reliable. When testing one with a multimeter(voltmeter) a good one will have much higher resistance between the prongs than an older model, mine had approx 39-40 ohms all round. The car idles and drives great now...except when cold so i guess i was right in thinking it was a two part problem and i still have one to solve. As its a different problem i'll be starting a new thread to solve it.

Thanks everyone, and kidwiththelaser, that link to the simple test page was a major help. Cool Mr Steve, thanks for the offer to take a look at it at the track, but i didnt get the email until too late in the day and wasnt sure at that point whether the car was safe to drive that far,