Cutting out on idle

[Wildhound]

Hey guys,

Having an issue which just appeared this week and I'm trying to figure it out. Went on holidays and had the car parked out at the airport. On the drive home, all was well, until I was about three quarters of the way there. Suddenly, any time I let the revs drop off (stopping at lights, turning a corner) the car would cut out, but only when in neutral. I thought I'd run out of petrol, until I turned the key and she started back up.

This happened all the way home from there, it must have cut out the guts of ten times. I took her out for a short spin last night and the same thing happened until I was nearly home, when I pulled in and she idled comfortably for a good ten minutes. Got out to have a listen to the engine and something in the bay sounded a little rough. Not the engine itself I don't think, and this might not even be related, but there was a kind of whirr which increased and decreased in pitch. I thought it might be the alternator starting to seize, but the battery is fully charged even after driving with the headlights, radio and a/c on for a while.

I'm assuming it's not the stepper because it first happened on the way home from the airport when the engine was well and truly warm. Apart from that I'm at a loss. Any suggestions?

Another little bit that seems unlikely to be related, the rev counter hasn't worked in a while.

[CJ]

In my experience, a faulty stepper can impact idle when warm, but not always. Clean it to start with. Faulty TPS can also cause this problem, do a diagnostic. Any battery resets of late?

CJ

[optical illusion]

Stepper motor problems kick in whenever they feel like it, give it a good clean, that should sort it.

[Muad_dib77]

Agreed.. sounds like stepper..

[Aido C]

When was the last time you changed the plugs? I a cylinder isn't firing that could make it cut and and the car would sound a little rough too. Is the any loss of acceleration?

[Wildhound]

Thanks for the suggestions guys.

I'm feeling both pretty stupid and relieved right now, having discovered the problem (courtesy of Dilogoat).

The throttle cable had loosened!!

Tightened it up a little and all seems well. I need to figure out what the other sounds were now though - although they might have just been a result of it idling so low. I've a decent drive ahead of me tomorrow so that should tell me if the problem is solved.

[escu_calin]

The throttle cable had loosened!!

how in the name of Artemis a loosened throttle cable can choke the car on idle?
the car still idle's well even if you unscrew the throttle cable altogether.. but hey.. wont accelerate!
seems to me if it were just that, when it'll get hot again will choke again.... if not; please anyone explain!

[CJ]

A loosley tensioned throttle cable shouldn't cause the problem you've described - have you overtightened it perhaps and in turn increased the idle speed which is in turn masking the issue?

CJ

[escu_calin]

have you overtightened it perhaps and in turn increased the idle speed
CJ

by doing so u kill the engine, sparks, coils ; your fuel consumption will go to the roof since the ecu will know from the TPS that the pedal is pressed .. and will try to prepare it for a sprint by enriching the mixture , and that affects the parts stated above

never ever overpull the accelerator cable; for rising idle you have the throttle screw, and not the one that keeps the valve in place.. that is a also NO TOUCH

anyway ... keep us informed

[Wildhound]

It's tough to tell where it's idling at the moment without the RPM gauge working, but it sounds about right. Possibly 100 RPM too high, but I reckon if I lower it a little it still won't cut out. Whereas before, when I managed to get it to idle without cutting out, it was idling extremely low at maybe 400 RPM or so.

You know how when you start it initially the revs jump up, then drop off sharply, and increase to a level point? Well it was during that sharp drop that it would instantly cut out.

So do I need to slacken the cable and start testing from there? Is it a bad idea to drive it to Wicklow tonight?

[CJ]

You know how when you start it initially the revs jump up, then drop off sharply, and increase to a level point? Well it was during that sharp drop that it would instantly cut out.

Has to be the stepper if thats the case

So do I need to slacken the cable and start testing from there? Is it a bad idea to drive it to Wicklow tonight?

Its OK if the cable is a little slack, it won't have any impact. You need to balance the idle speed using the adjustment screw on the front of the TB, speed @ hot is 750rpm.

If over compensating by keeping the idle speed artificially high gets you out of a temporary hole then leave it as is and clean the stepper when you get a chance. If that doesn't work, stick a new one in.

CJ

[Wildhound]

Thanks CJ. I'll clean the stepper on Sunday and see how it goes!

[Wildhound]

As usual, you guys were right!

Cleaned the stepper this evening and it had no effect so I tried Jonathan's (Dilogoat) and it worked perfectly. The stepper is totally nackered by the looks of it. They're pricey enough on Camskill, does anyone have one for sale?

[CJ]

Good stuff, at least you've got a diagnosis.

[escu_calin]

you can buy one from australia

here's the link:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0285595591

this guy is a shop.. so u can find more mitsi stuff

*edit
price for p&p is ~30 au$ so price wont rise above 100 E.. a 50 E economy versus camskill!

[Dilogoat86]

Is it the "teeth" around the plastic bit at the top of the stepper that wear? If so then even though mine works on Wilds car I'd imagine it's not got too much left in it. One side looks fine but the other side has almost worn flat.

[escu_calin]

Is it the "teeth" around the plastic bit at the top of the stepper that wear? If so then even though mine works on Wilds car I'd imagine it's not got too much left in it. One side looks fine but the other side has almost worn flat.

a picture beats 1000 words

use a camera and show us what u need ... is easier for everyone

[Wildhound]

Problem solved! I had a stepper motor in the shed that came with the engine I used for replacement on my last FTO. Lucky.

Thanks again for the input guys.