scoobyster

I had some problems with my MY95 GL after cleaning the engine with CD2 and hosing. These seemed to be resolved after drying everything out and resetting the ECU (which had been throwing error codes for the 4 injectors, the idle air control valve, and the throttle position sensor).

The car runs smoothly and as normal in driving at all times now, the only problem is the idle speed varies. Around half of the time it goes to its usual 700rpm, but often it will stick at around 1100rpm before gradually coming down to normal (usually over a period of a minute or two, but sometimes suddenly, and sometimes it refuses to come down to normal). A few times the idle has stuck up at around 2000rpm, usually after a period of hard driving some way into a long journey. Switching off and on again seems to solve it for a while.

ECU diagnostic checks still give the all clear and have done ever since the original reset. In fact I never got a CEL light even after the engine clean. The reset solved the problem for 50 miles or so of easy driving, but the sticky idle returned after some wide open throttle.

I replaced the idle air control valve yesterday which made no difference to the sticky idle. I did another ECU reset and at first the idle went very low, close to the 0 mark and the engine only just stayed alight. It soon sorted itself out and behaved fine for a 10 mile steady drive. At this point another diagnostic showed the all clear. I switched off and on again and went for a more spirited drive, the problem is back as before, again around half of the time.

What to try next then? Safe to go on track on thursday? Any advice would be much appreciated.

Kevin Groat

No help but my STi3 does this as well, been a few threads on it but none have got to the bottom of the problem - or if they have I've missed it.

B4 Alan

Yup having the exact same problem myself at the moment???
Was talking to a good Subaru mechanic today and he told me to give the TPS a good clean - they sometimes get full of crap.

Alan.

vulnax999

iTrader: (7)

<cough> MAF ? <cough>

B4 Alan

Nope - already replaced?????
I have a Diagnostics display monitor and it is telling me the Idle Switch is staying off when this happens.

CataIunya

Could be the MAP sensor....

Kevin Groat

Okay guys, TPS and MAP......?? what are they and where do I find them?

scoobyster

I think I might try some new plugs in mine, realised they're 18 months old. Can't get through on the phone to ScoobyClinic (who switched my IACV) to go back for a TPS today, so that will have to wait a few weeks.

Alan, your engine will be significantly different to my N/A, but I'll post this pic in case it helps.



The plug for the TPS is marked correctly (ignore the ?), I was told initially to make sure the connectors were clean and spray with WD40 to get rid of any moisture. Didn't make any difference to me, but give it a try.

No idea what the MAP sensor is, anyone off any info?

Cheers,

Ben

B4 Alan

Ben,

I was told to remove the whole unit that the TPS and IACV are plugged into
and give it a good clean. Might be worth a try?

Alan.

scoobyster

Thanks Alan, I'll give that a shot too. I've just taken a couple of my plugs out to have a look at them, I'm a bit worried about how white they look, also I think the gap is larger than it should be (think I've read 0.7mm, mine look around 1.0mm).
I was wondering if improoving the earthing might help at all, have heard that can solve idle problems, I think I'll be giving that a try.
I spoke to a Subaru mechanic about the problem today and had him stumped, all he seemed to suggest was to try yet another IACV.
Currently my car will behave faultlessly on some journeys, or have a sticky idle at up to 2000rpm for the whole of a journey.

scoobyster

Still having this problem, anyone have any other ideas?
If the revs stick at 2000rpm or so that's a fair bit for the brakes to have to work against, it's very noticable so I want to get this sorted out.

I replaced the plugs and have decided the old ones looked fine. Also added some extra earthing to chassis, ecu, alternator, manifolds, etc. and that has made little difference.

I've noticed I can drop the revs that it sticks at; when I'm stationary and it has stuck at, say, 2000rpm, if I turn the wheel the revs will often drop to around 1800. I can do this a few times to help them on their way down. Switching other electrical things doesnt seem to have the same effect though. Any ideas what this might indicate? Occasionally if the idle is stuck it will jump down to normal all of a sudden, more often though it slowly decreases (often in small steps rather than linearly) and takes about 3 minutes to reach the normal level. Switching off for a minute or two sets the idle back to normal, sometimes switching off and straight on again will too, but sometimes the problem will remain then.

What to try next? I still need to take off the TPS assembly as Alan suggested. If that makes no difference...? New TPS? Another IACV? New HT leads? Swap the lump?!

Cheers,

Ben

Turbo_Steve

Perversely, it COULD be water temperature sensor!
This can have all sorts of odd effects on the ECU when it goes.
Best thing to try is, when at fast idle, pop the lead off the sensor and see what the ECU does.
As already mentioned, the TPS would be a big question mark, as this seemed to appear after cleaning the engine.

scoobyster

Steve, the first thing a mate with a 1.6GL that had the same problem said was "water temp sensor". He said it had thrown an error to the ECU and brought up a CEL though, mine is doing neither. All the same, I'll give disconnecting the connector a try, any pointers as to where it is?
Many thanks for the reply.
Ben