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  #1  
Old 20th March 2006
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nbell nbell is offline
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Default Car suddenly won't idle when warm - stalls

Me car just got sick. Last week running fine, then a v slight stutter appeared when lifting off the gas.

Then the 'dipping idle at traffic lights' issue appeared, idle to 200-300 but always recovered (I resolved this symptom previously by changing the turbo dump valve).

Now it won't idle at all when warm, put foot on clutch and revs drop to 0 . Runs fine when going, got home 100 miles on dual carriageway yesterday, but brake when stopping without revs = stall.

Starts fine, warms up fine. Read some threads, checked for leaks, everything seems well connected, swapped out AMM with spare I had, cleaned AIC, removed Forge boost valve, checked all ok with that. Car still the same.

Ideas?

And am I correct to assume it can't be a vacuum leak if it runs ok when cold?
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  #2  
Old 20th March 2006
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Is your distributor in place? Check and make sure that the attachment 3 bolts are tight.

I've posted this 'fix' a great many times before, as the exact same thing happened to my 8v NA Auto. However, NO-ONE has ever said it was the cause! One day, someone WILL pat me on the back...............

The bolts had loosened by about 5 threads, and although the dizzy cap was still hanging on, the car kept stalling when coming to a halt and occaisionally when accelerating. After much head scratching I found the loose dizzy cap, tightened it up and waited for the NEXT problem top appear.
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  #3  
Old 20th March 2006
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Quote:
Originally Posted by tonyw
Is your distributor in place? Check and make sure that the attachment 3 bolts are tight.
Hi Tony. Actually, I read your comment in an old thread last night so when I checked the rotor arm etc earlier I gave the distributor a big of a waggle, seems rock solid, assumed thats ok then?
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  #4  
Old 20th March 2006
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Check the operation of the throttle position sensor. Test figures are in Bentley, if you have one.
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  #5  
Old 20th March 2006
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Quote:
Originally Posted by nbell
Hi Tony. Actually, I read your comment in an old thread last night so when I checked the rotor arm etc earlier I gave the distributor a big of a waggle, seems rock solid, assumed thats ok then?
I would imagine THAT'S ok then .
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  #6  
Old 20th March 2006
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Quote:
Originally Posted by Matthew
Check the operation of the throttle position sensor. Test figures are in Bentley, if you have one.
I did read yr advice on this in another thread, but avoided it as it looked a bit complex. But will test that next.

Bentley shows the test is quite straightforward. Can I ask;

a) How do I know if my car is a LH 2.2, 2.4 or 2.4.2 ?
b) The bentley test requires me to push the throttle and measure continuity. ** V sorry** if this is a dumb q, but I assume the engine must be off for the test? And if so, does that not flood the car?


Cheers for this help guys, as always this site is a life-saver.
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  #7  
Old 20th March 2006
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Gah... no details in Bentley for your car 'cos it's Lucas CU14 which the USA never got. Has Haynes for the figures? I expect they're on the forums somewhere.

No continuity measurement on CU14 AFAIK because the TPS is a potentiometer and not a switch. You need to measure the resistance sweep as the throttle's opened.

Test is done with the engine off, and working in the engine bay turning the throttle spindle by hand. Engine won't flood because the ignition's off.
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  #8  
Old 20th March 2006
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Quote:
Originally Posted by Matthew
Gah... no details in Bentley for your car 'cos it's Lucas CU14 which the USA never got. Has Haynes for the figures? I expect they're on the forums somewhere.

No continuity measurement on CU14 AFAIK because the TPS is a potentiometer and not a switch. You need to measure the resistance sweep as the throttle's opened.

Test is done with the engine off, and working in the engine bay turning the throttle spindle by hand. Engine won't flood because the ignition's off.
Thanks Matthew, v much appreciated.
Haynes has details for adjusting the Bosch TPS but nowt on the Lucas one, just how to remove/refit it. Maybe its just a replacement job then. I will research more posts.
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  #9  
Old 20th March 2006
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http://www.saabcentral.com/assets/do.../lucascu14.zip

One of the documents in there has specs for the lucas tps. Go get your multimeter Loads of stuff in that zip file, its a little misleading in the faq to say that its just for pulling codes.
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  #10  
Old 22nd March 2006
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Quote:
Originally Posted by Matthew
Check the operation of the throttle position sensor.
Matthew, top top bloke. New TPS solved the prob
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