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I have an odd car idle problem. When the car has been driven and I leave it for less than 2~ hours. It will not hold idle when started. I have to give it extra gas to keep it going. After 15-30 seconds it is then fine. for the rest of the trip. Cold starts are fine too.

Suggestions ?
 

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UP THE IRONS!!!
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Well, if it were vacuum related, it would not improve. My car did that once too, and before I could take it in to have it looked at...it magically disappeared and never returned. I'd disconnect the (-) battery terminal for about 5 minutes and reconnect it and see if that does anything as it may be computer related. There is probably a better explanation, but this won't do any harm, only takes a few minutes and may help. Good luck.
 

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Discussion Starter #3
I don't need to even try. I've had this for a while and its survived a dead/replaced battery(no battery in the car for over 24hours).
 

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no speed limits here
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I'd guess it's your IAC motor. Because it's a stepper motor, it has different modes of operation, ie. engine warm, engine cold, ac on, ac off. Maybe with the engine at normal operating temps., the I
AC at startup is allowing too much fuel at idle.
 

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Discussion Starter #5
Not enuff fuel maybe. But, too much does not make seem right(given I give it gas to keep it running)

Whould it change after only 30 seconds ? This only happens right after startup.
 

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what are you asking us for.. you are the admin here

Dont you read every post? :)

I'd say it is an IAC valve too.
 

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idle.....

I have a similar problem that I can't figure out.

My car doesn't idle at all. Sometimes when it is cold it will idle at like 200 rpms.

But most of the time I have to keep my foot on the gas when in neutral to keep it going.

I changed the battery, checked for air leaks, etc.
I have heard of the stepper motor thing, and have yet to check it.
The service manual has a procedure for checking the motor, and I'll have to look it up.

Both your prob and my prob sound like the same thing.

Every once in a while, the thing will idle perfectly when I first start it up. But that only lasts for about 3 minutes.

I'm taking the car to Mitsubishi if I can't figure it out this weekend.
 

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Alan,

I've been trying to figure why a time element (15-30secs.) is involved. As far as giving it gas to keep it running; you're bypassing the effects of the IAC by opening the butterfly on the throttle body.
 

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Alan92RTTT said:
I have an odd car idle problem. When the car has been driven and I leave it for less than 2~ hours. It will not hold idle when started. I have to give it extra gas to keep it going. After 15-30 seconds it is then fine. for the rest of the trip. Cold starts are fine too.

Suggestions ?
Alan,

Had the same problem last year and got the IAC motor replaced. No problems since. Also, if it is the IAC motor the problem will get worse, hell a couple of times the car was revving from 1K to 2200rpm on it's own. The car drove fine but once I stopped it just revved and revved and revved. BTW, that motor runs about $300 from Mitsu, thank goodness for my extended warranty.
 

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Discussion Starter #10
BLACK94TT said:
I've been trying to figure why a time element (15-30secs.) is involved.
The 15-30 seconds comes from how long after start I need to keep the rpm's up. It takes that long to stabalize. Then its fine.

I don't think its the idle stepper. Why you ask? Given your statement that "giving it gas to keep it running; you're bypassing the effects of the IAC " While giving it gas its not smooth, it runs rough(missing?) and still wants to stall.
 

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I have had the almost exact same problem sometimes. It and REALLY bothers me. It usally happens when the outside temp is over 80 degrees and I run the car with the a/c on I have found I try to live without my a/c on for most of the summer for that reason unless it's hot as hell then if I use it I have to give the car like 10 min or so time idle with no a/c on to ensure it starts ok.

The only thing I can think is happening is that possiblly there is a slight "heat soaking" of the head(s). The reason I think this is because I had it happen to me the other day when I REALLY beat the hell out of my car BADLEY for reasons of me having a bad temper :mad: Anyway I didn't let the car idle much before shutting it off and I went to start it about an hour latter and it did the not want to start like if I used the a/c and the outside temp was only about 70:confused:

Another intresting thing one of my friends has a 93 R/T tt that he gutted the precats and bypassed the main cat and he has the exact same problem I do with hard start after the a/c has been used. He also had the hard start problem happen after his thermostat stuck and got the car a lil hot.

I think it could have something to do with the no cats possiblly letting the cool air come back up the exhaust and cool the heads off to quickley? My car seems to get it REALLY bad, but then I have a small overboosting problem 18 lbs is ok on the stock fuel system right ?:eek: :eek:

I have asked other people about this with gutted cats and they seem to have no problems? I am going to try putting the main cat back on next summer sometime and see if that helps or if could possibilly have something to do with the injecters being old and acting up when hot, but I am AFFRAID I know what could be wrong but I just don't want to think about it right now and if you don't think about it it can't be the problem, right ;) Since I had almost the exact same problem on my 92 DSM after driving on the highway for a while and that turned out to have a bad head gasket. That cylinder compression was leaking in to the cooling chamber and it would over pressureize the cooling system enought to let air get trapped into the head and allow it to heatsoak and not want to start.

I bought my car used and it had a VERY leaky water pump I replaced my W/P and thermostat and all the cooling hoses but I don't know if anyone ever overheated it at all in the past. My friend dosn't know the history on his car either other than his waterpump leaked as well. I have put 10k miles on my car so far and had no overheating problems or loss of coolent but after I shut it off I hear it makeing weird noises from the raditor cap and my friend with the 93 dose the same??? mabey I will start a thread with cats and no cats and if you have hard starting assoicated with not having them.

I am pretty sure it's the begining of a blown head gasket but I am still in denial. I want to use my extra money for other more fun things right now other than motor rebuild. So I hope I can make it last till 150k and then I am sure the rest of the motor will be due for an overhaul as well. Mabey it will heal itself if I let it rest over the winter :)
 

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Alan, try taking a bottle of air intake cleaner, and clean out the throttle body as well as you can.. probably 1/3 of a bottle should be enough.. make sure your air filter is in good condition.
See how it reacts after that.. might have just needed a cleaning.. but that would be the first thing I'd suggest.
 

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BFA
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I had that EXACT same problem

RIght as I drove my car home from buying it, it happened. It ONLY happens if the engine is warm. I'd drive somewhere, come bakc home and park, and if I go back to start the car maybe an hour later, it would do that. I would say it happened about once out of every 5 times for about two weeks, then it went away. THen again a few months later, the problem came back. THen it went away for a long time, and it has happened only once since then. It DEFINITELY seems like an electrical problem, and not a throttle body issue, because of the way it happens. The problem is there, or it isn't. There wern't any half-assed starts. Either perfectly, or a bitch to start. I have done alot of mods since then, and I haven't had that exact same problem, but now I have a problem where my car likes to stall if I let the rpms fall too fast, I.E. pushing the clutch in when stopping or going into a turn and downshifting. I had to heel-toe brake to keep the rmps up when I downshift to keep the car from stalling. I also had alot of spark blowout, so I thought it might have been related. Well, after changing the plugs and lowering the gap, my car runs great, but still has the same stalling problem. I turned up the idle using the idle screw to 1200, and it still drops like it used to, but not enough to cause the car to stall. If the original problem was likely from the IAC, would this new problem also be from a bad IAC motor? I just had an engine rebuild from GTPro, so everything should be running right, and Brian says it shouldn't be anything to do with the rebuild. I actually got this problem along with the spark blowout after running 116 octane at the track, so I'm also thinking it could be my O2 sensors, but Manny at GTPro said that if they were bad, I'd get an engine check light, which I don't. Could the O2 sensors be GOING bad, and not yet kaput? I'm also running really rich, (I'm thinking because of the strong fuel odor and white smoke from the exhaust when I come to a stop after a hard acceleration or start my car) but I have an ARC-2 and the A/F guage isn't showing rich, except for a moment at cold start, and behaves like I would expect it to if it were tuned correctly. I heard about the IAC motor going bad alot in our cars, and with 121K miles, I wouldn;t expect everything to still be in perfect working condition. Any help would be great. Thanks
 

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RacerRT said:
Alan, try taking a bottle of air intake cleaner, and clean out the throttle body as well as you can.. probably 1/3 of a bottle should be enough.. make sure your air filter is in good condition.
See how it reacts after that.. might have just needed a cleaning.. but that would be the first thing I'd suggest.
YEAH this fixed a similar problem for me. If it is the IAC motor a computer diagnostic would probably tell you. I would try your throttle body first.
 

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Discussion Starter #15
James, outside temp is not a factor. it was 40 today.

I doubt the air filter is an issue its a K&N thats not even a year old. But, I will try and intake cleaner anyway.
 

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That is an intresting thought possibly a weak coilpack or something causing weak spark when the heat of the motor sits and bakes it? My car just did the hard start/bad idle thing today with no A/C on and outside temp of about 45 and starting to rain :confused: You think it could have something to do with the amount of moisture in the air? I know it's not my IAC I swapped the one in my car out with a new looking one from my parts car and it still dose the same thing, and I sold my old one to BLACK94TT and it works good for him.

My car usally dose the poor running thing for lilke 15-30 sec after running the A/C on a hot day but now it is getting to do it anytime with or without A/C now and if I don't let it have a min or so idle down time before shutting it off when you go to start it after an hr or so it BARLEY starts and has a hard time reving up sometimes lasts up to 60 seconds or more. Right now I am trying to do WAY too many other things to even think of dealing with it. I also am not really sure where to start looking?

Later,
James
 

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This all sounds like classic heat soak to me (unless its happening at cold temps). My VR4 just did it the last two days, when its been very humid, the temps have been in the upper 80's, and I didnt give the car enough time to cool down. It only seems to happen is re-attempting to start the car within 1-2 hours after shutting it down from a hot run, it struggles to idele, like its running on 3 cylinders, and giving it some throttle helps clear it up, gone usually within 1 minute. First thing in the moring its fine, either hot or cold, or if given enough time to cool down (either 2 hours or greater or idling the car for 1-2 minutes prior to shut down). Running higher boost seems to effect it (it does it more often), as does the A/C (the car gets hotter when the A/C runs, it puts more load on the engine to run the compressor). And, on the same days (same conditions), my 89 Toyota Supra did the same thing, which is a known problem with them (heat soak).
 

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mine never does that and I have stock intercoolers, so I don't think it is heat soak
 

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I've been having idle problems lately as well. I'm convinced it's the O2 sensors - which I know are bad. I took my IAC apart and it was spotless. My problem is different from yours, but maybe our problems have the same cause. I'd try cleaning out your plenum/throttle body and try the Seafoam-in-the-intake trick. That's what I'm gonna do when the new O2 sensors get here next week.
 

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My car did the same thing. I recently changed the ecu capicitors on my ecu even though they did not look bad or leaky and it solved the problem. I first changed the iac motor and although it helped with the idle it did not solve warm start problem then I decided to change the capacitors since they were only 5 dollars from john monnin b4 I took it to the dealer and it worked. I seem to notice most of us who have this problem are first gen maybe the ecu's just go around 10 years or so and maybe the were just faulty during these years.
 
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