The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support STM Tuned
Please Support ExtremePSI

420A Car idles but when throttle is applied revs out of control or dies.

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Redslayer

10+ Year Contributor
201
5
Apr 5, 2012
Federalsburg, Maryland
I had just finished putting my car back together from a rear motor mount replacement, and after refilling the coolant system which took quite some time of the car idling, I went to see how the car ran and as soon as I touched the throttle the car just went for the red line, even after I released the throttle (as if I was holding it around half throttle). I turned it off when it hit about 5.5k and let it sit for a minute, then restarted it. Now every time I start it, it either stalls immediately, or idles fine until I touch the throttle at which point it starts to run rough and then stalls.

Now, I considered maybe it wasn't getting enough fuel, so to test it I turned off the fuel pump when it began to stutter, but that actually made rev up then it idled better until it eventually ran dry and stalled. I tried switching it off then back on after it cleared up the bad idle, and it would immediately go back into stumbling until it stalled.

This to me tells me its flooding itself out, getting too much fuel the moment I touch the throttle. What I don't know, is what would cause that. Too say I'm tired of working on this car would be a grand understatement, but if its something simple then I'll fix it. Otherwise, I'm done with this car until I can pay someone else to work on it, because I'm just so tired of mechanic work it isn't even funny.

Quick note, I checked the actual throttle cable and it isn't sticking. Car ran fine before, but it sat for about a month because I've been too busy so I honestly don't know what changed.

I checked some of the other threads in the "similar threads" but most of them appear to be air related, which doesn't seem to be the case here.
 
Fixed itself.

Left it sit over night, went over and fired it up today just for the hell of it, and it runs fine now. While I was at it I double checked the coolant and made sure there wasn't any air in the system on the off chance it was over heating and just wasn't showing on the gauge for some reason. A couple little bubbles did come through, but nothing significant. So idk. It had been sitting without the battery for a couple weeks, so maybe the ECU just hadn't sorted itself out after everything was back together. Whatever, I don't care, it runs now so I'm not messing with it LOL.
 
One of the reasons could be the ECU trying to sort itself. Whenever I remove the battery from my '98 GS, it doesn't idle properly, sometimes under 700 rpm in idle and if I turn on the A/C on, goes around 500 rpm, almost shutting itself down. I usually take it for a drive for 20 minutes and after that it idles normal and works properly.

I didn't experience over rev though, but glad your car sort itself :)
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top