legacycentral bbs

When vehicle is still in warm up process, the idle is fine, but after it gets warmed up, it occasionally will drop down near 5-600 rpm, and idle very rough. did it this morning, after I parked at work, and as I was sitting there, it just popped back up to normal.....

thoughts on where to start looking?

It's hard to say what the problem might be with these cars.

I'd say start looking for any vacuum leaks in the intake/pcv piping.

But it also might have to do with your Idle Air Control valve or your Mass Air Flow Meter.

Are you experiencing any kind of bogging/power loss while driving?

Whats is "normal" idle speed when warm? When cold?

My Leggy often idles at 500 RPM and it is very rough. Doesn't seem right.

Yeah, I can't say my idle is overly great. I'm not sure if it's a wiring issue, or ECU issue....

Imprezive wrote: Are you experiencing any kind of bogging/power loss while driving?

I was, but I also had a leaky/faulty BPV. I replaced the BPV with a TurboXS BPV, and it's working great, and I haven't noticed any bogging while driving now. though it sometimes gets a little jerky.... (did before.)

I did find a spot in the intake trac that was letting air in after the MAF, and I closed it up...

I'm starting to think the rough idle is due to the overall aging of all the electronics. Because it seems everyone experiences similar problems with these cars.

The only way to really fix it is probably to just replace each sensor one by one...

Imprezive wrote:It's hard to say what the problem might be with these cars.

I'd say start looking for any vacuum leaks in the intake/pcv piping.

But it also might have to do with your Idle Air Control valve or your Mass Air Flow Meter.

Are you experiencing any kind of bogging/power loss while driving?

it was definitley very jerky/"boggy" driving it this morning... air and temp conditions the same as yesterday...

I do have a new intake tube coming just to be sure the crack I fixed is not an issue.....

+1 for IAC valve.

Imprezive wrote: The only way to really fix it is probably to just replace each sensor one by one...

been through most of them now

I think the only things left are IAC and the ECU

spark plugs, wires, coil pack, shit gas, gas filter, injectors are dirty, thick black shit all in intake + turbo, air filter, fule pump bag is dirty.... all in all the legacy turbos i had 500rpm is where its at give or take a bit and they are rock solid. even the new one i just picked up with 300,000kms on it is perfect.

do you have mods?

this isn't unusual for my legacy, I was watching the scantool as this happened repeatedly over the course of one morning and determined fuel trim was doing it; trying to correct for a rich condition at idle.

it's nothing to worry about, it could be part of a sluggish O2 sensor, low fuel pressure/tired fuel pump but mine has done it for years.

essentially when the engine is idling rough right then, it's running lean and the burn is hot/incomplete.

My car started showing this symptom after I replaced the plugs in an attempt to cure stuttering under load (which did fix the problem). But so far it's only done it twice that I know of.

I adjusted my IAC a little bit, but I think it was really due to bad O2 sensor.... it was also causing my jerkiness,a nd hesitation I was having....

it will occasionally have a little jerkiness now, but I believe it to be the fuel pump, as nearly everything else has been replaced

I'm waiting the for the O2 sensor and fuel pump to come in, then I've got a new downpipe to go with it.

so for now I'm just running with the O2 unplugged, and having a blast!