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1G Rough idle on warm start? 1G

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Alfa9373

Probationary Member
2
0
Jan 6, 2009
Littleton, Colorado
I have a 1990 Plymounth Laser RS turbo
Car has 219,000 miles
Car does not want to start right up after I have driven it for a while, If I leave it alone for anything more then lets just say 15 min after the car has been driven for a while it does not want to turn over and then when it does it just idles rough and then stalls out. I start it again and same thing. 3rd time as soon as it turns over I pump the gas until it revs up then keep it at high RPM’s and after I drive just a little bit and car does just fine running normal.
It seems like the fuel is the problem or the pump or something. Once the car is moving there is no problem. All cold starts are perfect no problems at all. But after I drive it for a while and the car gets warm and I go to start it again I have this problem.

1st post
 
I had a blown head gasket and the oil and antifreeze were mixing and made it start rough when it was cold. The turbo was shot also so i think the oil and antifreeze might have been mixing in there also. Now im doing a rebuild so i will report when its fixed.
 
do you have the fuel pressure regulator solenoid hooked up? it is supposed to close and bump the fuel pressure up to get rid of vapors that can occur from fuel sitting in a hot fuel system.
 
I've heard that this is a very common thing with DSMs. The general consensus was that this is caused by vapor lock in the fuel system.

Mine does the same thing, but it's not as bad as yours. It just idles rough for a few seconds, once I rev it up once or twice it's fine, and it never stalls out.

Unfortunately, I'm not sure what one needs to do to fix the
problem.
 
I've heard that this is a very common thing with DSMs. The general consensus was that this is caused by vapor lock in the fuel system.

Mine does the same thing, but it's not as bad as yours. It just idles rough for a few seconds, once I rev it up once or twice it's fine, and it never stalls out.

Unfortunately, I'm not sure what one needs to do to fix the
problem.

Yea I do the same thing once I rev it up it goes away, I talked to a friend today and he was saying it could be the fuel pump or maybe the fuel filter. Because this is my DD I really don’t want to put a lot of money into it and really just want to maintain it. I agree with you guys to about the vapor because it only happens when the engine is warm and after it has been driven and it has had a chance to just sit with the motor off for an extended period of time. I never have a problem with a cold start. You guys mentioned anti freeze and maybe oil mixing as well and this could be true as well. It smokes nonstop when the engine is running from the exhaust pipe of course, the smoke is white as far as I can tell. It also eats oil so I don’t know if I should rebuild the engine. But as I stated before I just want to fix the car so it runs the way its supposed to. Any ideas based on the new information I provided?

do you have the fuel pressure regulator solenoid hooked up? it is supposed to close and bump the fuel pressure up to get rid of vapors that can occur from fuel sitting in a hot fuel system.

I dont know what this is, im a newb when it comes to the engine

could be your thermostat plugs. does it turn over fast when you start it cold? my brothers car had a blow head gasket, and it would freeze up because there was water in the oil. it wouldnt start up.

it turns over fast when its cold
 
I dont know what this is, im a newb when it comes to the engine
on the firewall, drivers side, at the top there are 3 solenoids. it is the middle one. one end goes to the intake manifold and the other end the fpr. look on your hood and there should be vacuum diagram and it will show you which end goes to which. i don't think it matters but it is better to just hook it up correctly.
 
Just thought I'd chime in.. To those of you who brought up the fuel pressure solenoid, I'm having the same hot start issue. The deal is though, my fuel pressure regulator failed before, which caused fuel to get to the solenoid. Would that cause the solenoid to go bad? Im just wondering because they go for about 30 bucks, and during this time of the year i dont wanna spend the money to get a new one and not solve the problem. Also when you guys said u rev and drive off, does that disengage(?) the solenoid? Does it cause damage(running lean), or would i notice? My car runs fine afterwards too.
Also if I get the solenoid swapped I'll report back and let you know.
Thanks.
 
i doubt it would ruin it but i would just bypass it unless you're having a problem warm starting without it.
 
i doubt it would ruin it but i would just bypass it unless you're having a problem warm starting without it.

Ok, but wouldn't i still have the problem since the solenoid is use on warm/hot starts? Im still using a stock regulator.
 
if it has trouble starting on a warm start then you should keep the solenoid. if you have trouble running after you start it then it is another problem.
 
I'm having this same problem. Were you able to identify the issue? It only occurs sometimes for me, and will clear up after running for a few minutes.
 
Coolant sensor is fubared. Common thing to go out on 1G DSM's. When these go, the ECU thinks the water temperature is warm thus will not need to run rich for cold starts - is why you're having troubles until it warms up.

-DSM
 
No, did you read it all, we're all refering to a warm/hot start. Otherwise your right.

Also to the last poster, i havent resolvedthe issue. i ordered a fuel pressure solenoid 2 weeks ago from a vendor here and havent got it yet. I'll be calling them tommorow, since they ignored my last email. If/when i get it i let you know the results.
 
Sorry on the misunderstanding..I also had probs with hot starts and it was the ECU that was giving me fits. Replaced the ECU and that problem was "put to bed" in a quick.

..and since you're the same as me, the ECU is a MD128625 for 90 FWD Federal.
 
The Fuel Pressure Solenoid was the next thing I was trying too. I haven't ordered it yet though. And I have had my ECU repaired and socketed about 2 months ago, so I'm sure its good.
 
The Fuel Pressure Solenoid was the next thing I was trying too. I haven't ordered it yet though. And I have had my ECU repaired and socketed about 2 months ago, so I'm sure its good.

Well, I got the solenoid today...FInally.:confused: Anyways im still having the same issue. I also had my ecu repaired couple months ago by ECMlink. Next thing im gonna try is the egr blockoff, since ive had one laying around forever...
Good luck man, let me know if you find anything out.
 
I have a logger, but I'm not too good at logging since I don't really have any help with it. Either way, I will try to pull a log and get a video so we can pinpoint the issue. If we can identify ours as the same thing, I'm sure we'll get it sorted out by the smart people on this forum! Keep me posted as well!
 
I have a logger, but I'm not too good at logging since I don't really have any help with it. Either way, I will try to pull a log and get a video so we can pinpoint the issue. If we can identify ours as the same thing, I'm sure we'll get it sorted out by the smart people on this forum! Keep me posted as well!

Cool, I have a logger too, unfortunatly i have to wait till my tax return to get a laptop and the net..haha posting from my phone.. What type of logger/software are you using? Im running mmcd on a palm, and have some logs saved. I'd be able to compare yours to mine untill i can upload mine.. Unless i get a chance to use a computer, in which I'd try to get it on here.
 
I also use mmcd on a palm. I've been having problems getting the graph to display. I think it may be my palm though. Graph is selected, but nothing displays, even while I am logging. That's what's confusing. I've only seen my friend's logger going once almost a year ago, so I'm not sure if its something with my palm or the version of mmcd that I have. Anyway, I just ran my car for a while and couldn't reproduce it completely. It ran rough at times, but it wouldn't do it. I may try again in 30 minutes.

How can I upload the log? I tried but it's an invalid file type. Another weird thing-I don't see INJD in the Excel file, even though it was logged. I was able to log it after upgrading to version 1.8 of MMcd.
 
Its lack in oil pressure mine does it to. Once you rev it up and get oil pressure higher it idles normal again. Yours is just bad.
 
Bumping an old thread here to see if any of you guys have any sense of what this might be. I'm experiencing this in a Galant VR4. Warm startups give it fits. I rev the engine a bit go keep it running and get it out of hte parking spot and by the time I get it across the lot all is well.

I have a check engine light that is being triggered by the TPS. I suspected that might be the culprit, but based on others' input, this doesn't seem like a common pattern. I also had a suspicion that maybe it was the coolant temp sensor not working properly, causing the car to over-richen the mixture during the warm startup... but it appears from what I've read only the inverse is true - on cold startup a bad sensor will not allow the ECU to richen the mixture to allow the car to run right. Consistent with others' issues, cold startups are never a problem.

All this leaves me where I started, which is where this thread started - with no resolution. I'd like to hear from anyone with any ideas, and especially like to hear from someone who has solved this issue. It's not too much of an issue this time of year, but in about 3 or 4 months, I can imagine this will become a real annoyance.
 
Check all the obvious things first, boost leak, ICS resistance, TPS resistance. Get all those out of the way first, next let the car get hot to where the problem would start, and spray/ice the fuel rail, restart the car if there are no problems then you need a Phenolic Gasket for the intake manifold, this provides a heat barrier and lowers the temperatures.
 
i'm having the same issue . I have removed all the emissions and only have 3 vac lines now so I know its not a vac leak. i'm replacing the temp sensor tom. fingers crossed, and the fps has been removed. has anyone ever actually fixed this issue some where out there. I have an upgraded fuel pump and injectors and gm maf.
 
Going to give this thread a 3yr bump. I'm having the same issue. Went away for awhile then today it started again after driving it for an hour working on the tune. I pulled up to my house and shut it down and was reviewing my log. Went to restart and it would just crank. Went over everything under the hood all good monitoring my data stream showed nothing odd. Ran the fuel pump via link to verify fuel pressure which was good. Said screw it let it cool off for an hour and it restarted without hesitation. I'm leaning towards my ecu taking a dump. It was rebuilt probably 10 or 12 years ago. All wiring is good I made my harness with all new connectors from Sheridan. Just curious if anyone has a direction to pursue before I send my ecu off to ecmlink.
 
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