Intermittent Idling Issues - ECU or Stepper?

[scarecrow]

My FTO took it upon itself to decide that after $3500 in rego/insurance, and $1500 in major servicing, that it - on occasaion - doesn't want to idle.

Couple weeks back, driving home one day the engine dropped out during a slow gear change round a corner (dropped to idle speed, then to off). Following that for the next 10km's home in stop/start, if I took my foot off the accelerator and let it idle BAM she'd die. Had to juggle the clutch/brake/celerator all at the same time to get it back to my place

Unplugged the battery for half hour, and all was right with the world again.

Took it in for a service at UAS, they didn't have any troubles, got all the fluids and a bunch of other stuff done then took off home. No problems.

Couple days later taking it to get the pink slip done, was idling at a set of lights and the revs laboured for a bit, then dropped off entirely. Had to ride the accelerator the rest of the way there.

The place I was taking it to happen to do pretty good auto-electrical stuff so I asked them to fix her up. Wouldn't idle at all at the shop so they took the stepper motor off, ran a bunch of fancy tests, appeared fine. Checked all the wiring and related stuff, then summised that nothing else was broken, so it must be the computer.

Did a reset of the computer an it was fine again on the way home.

Couple of days later... well, no iddling love.

Bah and humbug.

So, I'm hesistant to pursue the "computer must be broke" avenue, because that will probably send me broke. Should I just grab one of those nardak steppers (yes I've read all the old threads)? Has anyone had experience with those guys?

Kempys want $195 + shipping for a rebuilt one.

Is it an easy swap over job? I have zero experience with the stepper motor, only actually found it in the engine bay last night.

Oh and if anyone wants to comment on ECU replacements/repair i'd be all ears!

Thanks


....alternatively, you can just buy my car, i'll let it go for like, $9000. Come on, take it. Just rego'd/serviced. Carbon fibre seat belt guides. CARBON FIBRE!!

[Bennoz]

Long time no see Scarecrow!

You checked the error codes?

www.ftowa.com/html/workshop/workshopart07.html

Could be stepper, could also be the TPS (Throttle position sensor.) The ECU codes may shed some light on it.

[I8A4RE]

Man if someone is nice enough maybe they would let you swap stepper motors and see if that fixes the problem, isnt there a DIY in sydney coming up. In saying, have you checked the ecu error codes?? cause it seems (from your story) that everytime you reset it, its fine for a while?

My straight out guess would be its the stepper motor though and is easy to swap to do.

[scarecrow]

I know, it's been a forever since I've logged on and actually posted anything. I have been reading up on my fto news occasionally though!

Browns reckon they checked that before they reset the system and there were no error codes being brought up. I might check myself though if i've got time tonight. I'll fire the car up and see if she wants to idle. It seems fine when dead cold. But there doesn't appear to be a link between how long it lasts before croaking again.

[Bennoz]

Yeah, you'll wanna try & check the codes whilst is is playing up.

[I8A4RE]

Yeah, you'll wanna try & check the codes whilst is is playing up.

Geez you must have bet me by like seconds ben

[scarecrow]

Okay, so took off the drivers side plastic stuff under the steering wheel and electrical taped a wire into pinout 1 of the MUT-II connector. No errors - just a constant blink.

Started the car, lo-and-behold, the bitch idled. Thought, great, its just a matter of time I suppose. So I let it get warm (30ish minutes) and gave the accelerator a couple of jabs.

It was dropping pretty low coming off the throttle (~500rpm) but not struggling (battery/engine lights on etc).

Turned on the aircon an it was dropping a little lower still, but not stalling.

After much piss-farting around with a stuck nut (haha) I screwed the idle in a little so it ran a bit higher - 900rpm warmed up, aircon on.

Jabbed the throttle a few times, and the reactions were a little odd. Some times once off the throttle it would plummet to ~500rpm and "catch" itself. Not yet struggling badly or stalling. Other times it would ease back from 3000rpm or so, rest at 1000rpm, and finally drop back to ~900ish.

Decided to take it for a drive, wire still connected, to try and catch it playing up. 20minutes around the local area with short bursts of driving, pulling over to the sidewalk, repeating, and I was getting the same behaviour.

A couple times the lights came on very faintly coming off throttle (when the rev's dropped fast), but it never really laboured. Again, generally it would just coast down slowly to the ~900rpm set idle.

Wierd right?

So, I'll give it short runs like that for a couple more days, have a piece of sh*t ford something or other from the days of old sitting around but its a bit of a death trap. Full lock turn in the wet at any speed = out of control crazy times. Heh.

[I8A4RE]

Yeah sounds to me like stepper is on its way out

Other times it would ease back from 3000rpm or so, rest at 1000rpm, and finally drop back to ~900ish.

Thats what it should be doing all the time

[scarecrow]

I managed to adjust my idle, using the wrong screw

I turned the one on the bottom of the throttle cable assembly, long phillips screw sticking out with a nut lock on it. When I turned it out it had no effect, when I screwed it in the idle rose.

Supplanter sent me a pick of the actual idle adjustment screw and its, front facing.


Uh, any insight into the one I fooled around with? The car didn't catch fire, and the idle rose, so, can I call it a win anyway?