Revs won't drop !

[TeGriffic]

On my Griff 1992 4.3, the revs are not dropping below 2400. Seems to have started just like that. If I rev the car, the revs come back to normal idle but then climbs again to 2400 within a second. If I turn of the engine and wait about one minute then start again, I’ll get about 30 seconds during which time the revs will climb to 2400 again and stay there. Any ideas what’s happening here ? Could it be something to do with the management system ?

[JonRB]

You need to get your fast idle adjusted.

[tvr4ever]

Try disconnecting the ECU, leave it disconnected for a few minutes. Then reconnect the ECU. Helped me a few times.

Fred

[TeGriffic]

I think cutting power to the ECU accidently was the problem. I did this with a cold engine. Do you think getting the car to running temperature and then disconnecting would be better ?

[jimduncan]

Before doing that, just check coolant levels

That'll do it !

[TeGriffic]

OK, just read the manual - clearly I’ve misunderstood the ECU, I thought this was soft coded. Obviously looks like it might be the stepper. I’m wondering, would a stepper failing or jamming increase my revs by over 1000 – does the stepper adjust to that degree ? Sounds a lot to me.

[griff430]

I had the same sort of behaviour from my old S3 a couple of years ago, after a very wet trip to Le Mans. It turned out that rain had made it's way through the bonnet air intake and into the throttle sensor. I changed that, and everything was back to normal. I don't know if it would be the same on a Griffith, especially as the throttle sensor is well away from any air (and therefore rain) intakes? Maybe worth investigating though??

Dan.

[Griffer]

You would be suprised the diference the stepper can make to RPM, had exactly what you decribe on my Griff 4L,cleaning the stepper motor cone and the seat cured it for me 18 months ago with no further problems, make sure the stepper is sealing properly as well, when I purchased my car it was loose and caused a massive air leak, revs went ballistic with that.I used carb cleaner spray to remove carbon deposits.Be careful not to overtighten though, new ones are expensive.Cant remember now if a gasket ring is fitted or not.

Good luck,
Griffer

[Reeso]

Griffer is spot on. I had the same problem on my 500SE and it was my stepper. Cleaning works most of the time, however a new one is about £80 so lets hope cleaning works!!!!

[TeGriffic]

Took it out last night and cleaned it. Going back in this evening and then, hopefully, all will be well.