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2G Car Idles horribly and will turn off if gas is pressed

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Joe' GSX

5+ Year Contributor
89
8
Mar 30, 2018
Houston, Texas
My car shut off on me the other day while driving , good thing I was around the corner from the house. I turned it on and it was horrible , It idles at 450 rpm and Goes slightly to 500 then drops to 150 , barely staying on , you can go into gears but if you push the pedal a little too much it dies. The car is shaking sounds like if no gas is passing through , Only codes im getting is p1105. I search it up and it came out to be the fuel pressure valve solenoid , but They also said that had no effect on car performance. Car is straight piped , No cats etc If that helps.
 
That happened to me with old TT Stealth. Checked for boost leaks and found one of my IC couplers had worked loose. Taking care of the boost leak took care of my situation. Any chance you’ve looked to see if you have any boost leaks?

Bryan
 
That happened to me with old TT Stealth. Checked for boost leaks and found one of my IC couplers had worked loose. Taking care of the boost leak took care of my situation. Any chance you’ve looked to see if you have any boost leaks?

Bryan
i just did today it had a coupling loose in the bottom piping , so I fixed it and clamped it up , started car , and was fine for about 6 seconds then same thing over , checked all the piping and there is no boost leaks , double checked hoses and no vacuum leaks
 
Does it die only when you leave it in idle? When you start up, can you keep engine on if you apply gas pedal? If you're positive no boost and/or vacuum leaks are present, have you moved on to check your Idle Air Control (IAC) valve? I may be triggered to open on start-up, then might stick in the closed position after warmup, which would starve your idle.
 
Does it die only when you leave it in idle? When you start up, can you keep engine on if you apply gas pedal? If you're positive no boost and/or vacuum leaks are present, have you moved on to check your Idle Air Control (IAC) valve? I may be triggered to open on start-up, then might stick in the closed position after warmup, which would starve your idle.

It stays on when I turn the key on , engine will start but rpms will be at like 250 then move to 450 then back down, itll stay on , but if I press the gas pedal like half way when i let go the rpms drop all the way and it shuts off. When I accelerate i can hear the belt squeaking too. I can post a video on youtube of what the car is sounding like . Does the fuel pressure control valve actually not affect anything ?
 
It stays on when I turn the key on , engine will start but rpms will be at like 250 then move to 450 then back down, itll stay on , but if I press the gas pedal like half way when i let go the rpms drop all the way and it shuts off. When I accelerate i can hear the belt squeaking too. I can post a video on youtube of what the car is sounding like . Does the fuel pressure control valve actually not affect anything ?
Of course it could affect something. This is part of the troubleshooting process. Keep calm and troubleshoot on. Have you checked your plugs? Are they dry/wet?
 
Okay, the way you're describing the gas pedal action and the idle behavior following you releasing the pedal, tells me it has something to do with your IAC aka ISC. Plenty of tutorials on replacing the ISC. Good luck:D
 
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Heres the video on the issue, ill look into the isc replacement

Are you running a front oxygen sensor?

Does the car run better with the mass air flow sensor un plugged?

The fpr solenoid helps with hot restarts, it should have a vacuum hose to it from the fpr to the intake manifold

Your engine bay video appeared to show you don't have a vacuum source hooked to your fpr
 
Did you pressurize the system to check for boost leaks or did you just check the couplers?

It runs fine when you first fire it up because it is still in open loop. Once it appears to go into closed loop it carps the bed. Any data logs you can share?

Checking the timing wouldn't hurt, but as someone who had just miss timed his car by a tooth, it doesn't sound like that. I agree that ISC, o2 sensor, or a vaccum leak could all be the culprit.
 
Remember, just cuz you get an error directing you to a particular component, does not mean that is in fact the failure point. It may be a symptom of the real problem.

Also, oops, I did forget about the o2 sensor open/closed loop function. And since you're getting an error related to your fpr, it could very well be due to your o2 sensor. On startup you are in open loop mode, where your ECU does not receive a feedback signal from your o2 sensor. Your ECU thinks your air/fuel mix is optimum and your engine seems to run decently because of it. After a brief period of time, your ECU switches to closed loop mode. This is where it then relies on that feedback signal from your o2 sensor to regulate your a/f mix. If it does not receive that o2 signal it will not be able to properly regulate the correct a/f mix to keep your engine running, hence your eventual shutdown.

Based on glancing at your video, I doubt your timing jumped. I concur with the o2 sensor comments. I have a feeling, that between the o2 sensor and ISC, you may solve your problem.
 
Are you running a front oxygen sensor?

Does the car run better with the mass air flow sensor un plugged?

The fpr solenoid helps with hot restarts, it should have a vacuum hose to it from the fpr to the intake manifold

Your engine bay video appeared to show you don't have a vacuum source hooked to your fpr
When I unplug the maf its stable, I changed the MAF as the first troubleshoot, and it did the same thing , it was a reman so It couldve been defective?
 
Fix the plug wire routing, it's not causing the idle issue but will cause problems later. 1 & 4 together 2 & 3 together but keep the two pairs apart as much as possible.

The ECU is trying to make the car idle but I suspect the IAC/ISC is dead so all it has left is the timing to play with. Measure the IAC coil resistance to see if the ECU has been damaged. Anything below 20 ohms can roast the drivers doe the valve. Open the BISS up and see if you can get it to idle better but you have to readjust once you fix the IAC.

Fix the FP solenoid. While it's not likely causing the idle problem and isn't critical to general operation the fault is causing the ECU to behave differently than it would if there wasn't a fault.

Get the battery fully charged before going much deeper. Low voltage can cause other issues and potentially damage the alternator.
 
When I unplug the maf its stable, I changed the MAF as the first troubleshoot, and it did the same thing , it was a reman so It couldve been defective?

If the car runs better with the mass air flow sensor un plugged you have a vacuum leak.

The map sensor takes accurate readings of engine suction at idle, with the maf unplugged the engine runs on map sensor readings at idle.

Perform a boost leak test and make sure you are very thorough
 
UPDATE :
Car worked after the 3rd mass air flow I put in there. Kept getting defective ones. I have a starting problem now , Not clicking so changing the starter now. Thanks everyone for the help :D
 
UPDATE :
Car worked after the 3rd mass air flow I put in there. Kept getting defective ones. I have a starting problem now , Not clicking so changing the starter now. Thanks everyone for the help :D
I'd say it's more likely you have bad wiring and you'e temporarily made contact. Switch out another maf and switch back to check. Still could be bad maf but don't rule out wiring just yet.
 
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