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This post has been edited by Beaniemoo: 31 January 2015 - 08:34 PM
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Over Revving Unless Stationary
#1
Posted 31 January 2015 - 08:25 PM
Hi thereI've been searching and have found lots of information on over revving pumas, it seems pretty common but haven't found anything which matches my fault specifically.I have a 2000 Puma 1.7My car idles at between 3000-4000 revs when you dip the clutch, but, as soon as the vehicle becomes stationary the idle quickly returns to normal.The fault is consistent with these symptomsI have a code reader and it had a fault for throttle position sensor, but if that was faulty why would if the car is moving or stationary make any difference. I've cleared that fault and I will recheck tomorrow to see if the fault has returned and check the values.I have cleaned out the idle air control valve, throttle body and made sure the throttle is closing correctly and no breather or vacuum hoses appear to be split or collapsed.I disconnected the battery and it stopped faulting for a few miles but then once again returned.I've read about power steering pressure sensor wiring breaking so I'll check that tomorrow too.As my symptoms seem very specific I was wondering if anyone had any experience with this fault as there appears to be a wealth of knowledge on here
#2
Posted 19 February 2015 - 02:28 PM
Maybe you've sorted it by now, but in case you haven't or this helps someone else...
Firstly, as I understand it the car only 'idles' when stationary, i.e. the idle control only kicks in when the car isn't moving, the throttle is closed and the engine revs have dropped below a certain value. If the car is coasting (in or out of gear) with zero throttle then it's the usual part of the engine management dealing with the amount of fuel going into the engine. That's why you can have this fault when the car is moving and it seemingly vanishes when the car comes to a stop. In the same way, with a normally-working car, even when coasting slowly to a stop with the clutch down the revs will be seen to drop slightly once the car comes to a complete halt - that's the idle control taking over.
Kas and Fiestas have had similar issues to this due to a fault with the TPS. A post on Honest John describes it in more detail. We had the same thing happen to our Ka, though sold it to a dealer before fixing it.
Firstly, as I understand it the car only 'idles' when stationary, i.e. the idle control only kicks in when the car isn't moving, the throttle is closed and the engine revs have dropped below a certain value. If the car is coasting (in or out of gear) with zero throttle then it's the usual part of the engine management dealing with the amount of fuel going into the engine. That's why you can have this fault when the car is moving and it seemingly vanishes when the car comes to a stop. In the same way, with a normally-working car, even when coasting slowly to a stop with the clutch down the revs will be seen to drop slightly once the car comes to a complete halt - that's the idle control taking over.
Kas and Fiestas have had similar issues to this due to a fault with the TPS. A post on Honest John describes it in more detail. We had the same thing happen to our Ka, though sold it to a dealer before fixing it.
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...it was the wrong resistance of the tps in the idle throttle position that was causing it - it seems that this is a design flaw and that TPS is set to work near the "edge" and over time when the material changes its properties this causes it to go over the edge - and overrev...the middle pin is the slider and changes the voltage as the throttle turns. When you turn the key (give a contact) and measure the voltage between it and the chassis in idle, it has to be 0.4 V. In my case it was 0.55 V.
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I found this page talking about idle voltage on the TPS slider pin Got out the multimeter and found that at idle, without the engine running, I was reading 0.65v. [I did stuff] Now when I checked the idle voltage I was around 0.42v. Took it for a spin and it again runs like a dream!
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