Throttle sticking/won't start...
 

So my Evo has 2 major problems:

...Above 4000rpm the rpms will "stick" and "float" up and won't want to come back down. So if I let off the gas and put in the clutch, the revs will stay up at 4000rpm, or higher, depending on how high I let it go...

...about a month ago, my car wouldn't start. Took it in to Works and I guess something in the immobilizer key reset the ECU and the engine wasn't getting fuel. They fixed it, I brought it home, drove it for a couple days, and now its stuck again. This is the really annoying one since at least with stuck revs I can at least drive it. I'm just lucky I guess that the car has only had a problem starting at home and at Works, and not someplace where I'd have to have it towed.

Has anyone seen ANY of these problems before, and can anybody shed some light on my situation?! I've heard of a number of '05 Evos that have a similar sticky throttle issue, and Mitsu is ignoring it (despite a few Works customers confronting them AND ECUTech putting out a "fix" for it, which I haven't tried since my car is DEAD). Both these problems are Mitsubishi factory related, why does Mitsu SUCK so bad?! I'm Bavarian by blood and Bavarian by usual car choice and would have assumed that when I sold my fine BMW for a Japanese econo-box I would be getting an uber reliable car... any help would be appreciated.

Check the accelerator cable, perhaps it's binding within its sheath. You could have someone step on the gas pedal (while the engine is off), while you look at the range of travel at the throttle body. Or perhaps the throttle butterfly itself is sticking, in which case you may need to rebuild or replace.

Sorry, can't help you with the other problem. Good luck.

P.S. Do you work or drive for TMS?

So we actually have been hunting this problem for quite a while now... about a year. It is nothing mechanical. EVERYTHING has been replaced. It seems to be the IACV for sure, but something in wiring, not in the unit itself, as it was also replaced numerous times.

TMS... haha... I race in an old Touring Car of his in BMW Club but check back in with me in a month or so... :cool:

Hmm... not sure what else the problem could be then since it appears you've done a pretty thorough diag. Perhaps you're onto something with the IACV. Have you tried swapping ECU's from a junker... perhaps to elliminate any wiring or computer issues?

On second thought... the IACV may not have much to do with your issue, because as you're well aware, the TB is completely mechanical in terms of actuation unlike our BMW's. Does the throttle simply stick past 4k and stay up, or does it gradually decline? Or, will it abruptly drop if you kick the pedal a few times while coasting?

Say hi to Will for me. {thumbup}

You are just getting the typical 05 throttle hang.

Yeah, it is definitely electrical, and I'm pretty positive there's something fishy in the wiring somewhere. We have gone through 2 complete ECUs on my car (the whole thing, what would be the DME on a BMW) and the problem is still there.

I have driven a couple people's '05s and have felt their throttle stickiness, but mine is beyond bad. Like I'll rev it up to like say 6k. I'll put the clutch in to watch the revs. It will hang at 6k for a couple seconds, then sloooooowly start to drop, then pause at 4k and just stay there. If the clutch is NOT disengaged, so if I'm braking, you can feel and hear the engine really try to counter the braking until it hits 4k and then it DROPS, and at the track, the ABS kicks in. So its quite an annoyance for me.

I'm not sure what to do. I was literally starting the car to drive it up and get the "fix" for the ECU that Pete found, but of course, now it won't start...

Unhook the throttle cable from the throttle linkage on the throttle body and work the throttle by hand. Does it stick anywhere? Now work the cable and see if that offers too much resistance to sliding back and forth.


edit:my reply was started before I saw the above additional comments..

Already tried, definitely electrical, probably wiring...

You see... that's where it baffles me. If the throttle were computer controlled (drive by wire), then perhaps... but even if the IACV or ICV were faulty, or receiving incorrect signals from the ECU, once that throttle butterfly closes, RPM should drop proportionately. The IACV doesn't actually control the butterfly actuation in the TB; just regulates the amount of air bypassing the throttle plate at idle position. (edit: in your case, your throttle is sticking past 4k)

It's gotta be mechanical. I say unhook the throttle cable. Start the car. Use your hand to open and close the throttle body. Once you reach the sticky point in the rpm band, forcefully or quickly return the throttle body to idle position. At this point, it can't hurt to try...

stepper maybe?

throttle hang and idle stepper table


theres a PDF in there that explains how the IACV doubles as a throttle bypass for emissions, and keeping up oil pressure in sudden vaccum for turbo applications, as well as protecting the turbo.

you can test if this is your problem by getting the RPMs up to hang, and then depressing the clutch enough to activate the clutch switch. to get them to hang you have to have some decent load in the upper RPMS, so a little WOT will get it to hang.

the car should immediately start engine breaking as soon as you activate the top clutch switch.


edit: the 'fix' is near the end of the thread, you just modify a few cells in the idle stepper table. the severity of the hang all depends on what you have for mods.


edit 2: as for the not starting. are you running an ecutek tune? the immobilizer does not reset the ecu, its the ecu being reset which may be killing the immobilizer. if you flash the ecu with the wrong immobilizer code or somehow the immobilizer code is being reset in the ECU, you obviously can't start the car. this is not a problem with stock cars, and i've never heard of this problem with ECUFlashed cars spontaneously resetting the immobilizer code.

i have always heard about people experiencing this problem wit h05's, so my guess would be to try a different iac.

Thanks ALOT... I forwarded this off to Pete to see if he knows what its about... but before I can worry about how my car runs, I need it to run at all.... :(