Discussion
My Chim is a '96 4.0 with 32K miles.
While running on choke it's fine. Once the temp is 60-70+, off choke I presume, it idles at 2500rpm then sometimes drops to normal (800-900rpm) or stalls. Even when up to normal engine temp when I stop at a junction it does the same. Looking at Steve's it suggests a dirty or bad Idle stepper motor.
Anyone seen similar, ideas etc???
Regards
While running on choke it's fine. Once the temp is 60-70+, off choke I presume, it idles at 2500rpm then sometimes drops to normal (800-900rpm) or stalls. Even when up to normal engine temp when I stop at a junction it does the same. Looking at Steve's it suggests a dirty or bad Idle stepper motor.
Anyone seen similar, ideas etc???
Regards
I had and still have similar problems to you, except the high idle speed is around 1400 rpm for me. Definitely worth doing the stepper motor - took me about 5 mins to do, but you do need a big adjustable spanner as the hexagonal plastic 'nut' around the stepper motor is over 30mm in size. I ended up with requiring a 12" adjustable to cope. That aside it's really easy to do. You just need to wipe the cone of the stepper motor clean with white spirit as described in the bible and replace it.
The alternative cause of such idling problems is the throttle pot. Having cleaned the stepper motor myself and not rectified things I reckon that this is the cause of my problems. However since my next service is very close I'm going to leave that problem to the garage to fix. I'll let you know how I get on, if you still haven't had any luck by the time she goes in for service. Whatever else this is a common fault and generally curable at a small cost.
Cheers,
Steve
(and Bright Yellow Chimaera 5L)
The alternative cause of such idling problems is the throttle pot. Having cleaned the stepper motor myself and not rectified things I reckon that this is the cause of my problems. However since my next service is very close I'm going to leave that problem to the garage to fix. I'll let you know how I get on, if you still haven't had any luck by the time she goes in for service. Whatever else this is a common fault and generally curable at a small cost.
Cheers,
Steve
(and Bright Yellow Chimaera 5L)
Had the same and still have to some extent. Replaced stepper motor (£80 ish) which settled the idle really well but didn't stop it stalling at Junctions occasionally, especially at the bottom of hills.
Have heard throttle pot voiced before and will try that next. I'll have to leave it to the garage though (don't know what it is really).
let me know if you have any success. This quaint characteristic is beginning to P me off!
Have heard throttle pot voiced before and will try that next. I'll have to leave it to the garage though (don't know what it is really).
let me know if you have any success. This quaint characteristic is beginning to P me off!
Black plug with a wire connected to it at the top rear of the plenum chamber, driver's side (the big lump on top of the engine). Unclip the wire, then use a big adjustable wench 
to loosen - it's plastic so be careful. Clean off the end 'knobby bit' with a bit of white spirit or similar. Don't over tighten it.
T/.
to loosen - it's plastic so be careful. Clean off the end 'knobby bit' with a bit of white spirit or similar. Don't over tighten it. T/.
Cleaning the throttle pot is not exactly difficult, one screw on the jubilie clip on the big black hose going from the airflow meter to the plenum chamber, move the hose clear, wedge throttle open, spray in hole with carb cleaner, or just wipe with a rag with a hint of petrol, note how dirty the cloth is, and then put back together, simple.
quote:
Cleaning the throttle pot is not exactly difficult, one screw on the jubilie clip on the big black hose going from the airflow meter to the plenum chamber, move the hose clear, wedge throttle open, spray in hole with carb cleaner, or just wipe with a rag with a hint of petrol, note how dirty the cloth is, and then put back together, simple.
That's a good thing to do but technically it is cleaning the throttle butterfly rather than cleaning the throttle pot. But it's something that does need to be done regularly and if the person who services your car doesn't bother, it can eventually lead to idling problems.
Cheers,
Peter Humphries (and a green V8S)
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