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2000 STS RHD 194,150 miles. what's a speed limiter???
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219 Posts
Discussion Starter #1
gave the STS a hammering last night, WOT, held the gears manually and generally blew the cobwebs out.
after about an hour of driving i noticed some hard downshifting into 1st at a few junctions and a short while later as i got to my destination the car was idling at over 1500rpm.
turned off the motor, waited a minute and restarted and found it idled at almost 2000rpm before dropping to 1500 again.
left the car for 2 hours and it did the same thing. as it was dark i drove to a gas station and looked under the hood for anything out of the ordinary. checked for codes and there were none, really, no codes at all, there's a cadillac first!
thought that while i was there i'd fill up. turned off the motor and put in half a tank of fuel.
restarted to drive off and the idle was back to normal.
so, i'm guessing that maybe the tank had pressurised, but there was no noise when i removed the gas cap.
anyway, i just thought it was weird.
 

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99 Seville STS, 08 STS4 N* 1SG F55
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3,516 Posts
Maybe it temporarily switched over to displaying metric RPMs. You will need a metric left-handed Vice-Grip to adjust.
 

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2000 STS RHD 194,150 miles. what's a speed limiter???
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219 Posts
Discussion Starter #4
i think i know the problem, maybe it was idling at a healthy 750 rpm and i'd accidently switched the display mode onto currency converter, could it have been displaying in $ intead of £ ? :)
 

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2000 STS RHD 194,150 miles. what's a speed limiter???
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219 Posts
Discussion Starter #6
it's happened 3 times since i first posted but the idle hasn't been quite as high as it was the first time.
i checked under the beauty cover and the induction pipes and aslo checked to see if the throttle plate was sticking.
here is the strange part, removing and replacing the gas cap with the motor off solves the problem, where as turning the motor off then on again doesn't.
so maybe there is a problem with the tank breathers and evap system.
still no codes (ok this time i got a tilt steering wheel code, again) so i'll just have to keep looking and waiting.
 

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White Diamond '03 DHS (with DTS floor shift)
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86,987 Posts
here is the strange part, removing and replacing the gas cap with the motor off solves the problem, where as turning the motor off then on again doesn't.
That IS strange. Do you hear a vacuum or pressure release when you remove the cap? If so, which? Vacuum would be a bad cap. Pressure might be EVAP.
 
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