Hi
My Pug 306 has recently developed an irritating fault. When starting the car from cold it will idle steadily at 1000rpm then the revs will jump up to 2000rpm after a couple of mins. They then immediately drop back to 1000rpm. Sometimes, after another couple of mins, it will happen again. It can also happen after moving off and is especially disconcerting in slow moving traffic.
Also, the engine will sometimes take a while to fire when cold (It used to start straight away, even on very cold mornings).
Neither of these symptoms are present when the engine is started when warm (The idle is very smooth at around 800-900rpm).
A friend (who knows more about these things!) suggested I replace the Idle air control valve which I did. The problems are still there though. I have also reset the ECU which initially made things worse then settled back to the above pattern.
Any advice would be greatly appreciated. Thanks
Edited by Dynamic Dave on 14/10/2008 at 13:17
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Hi Dr4d,
My old 306 (00 1.6) had a similar problem. It was very difficult to start from cold, plus when sitting at traffic lights, it would rev uncontrollably for around 5 seconds and then settle down again.
I took it to a Peugeot dealer who diagnosed the problem as an "open circuit thermistor". They changed that (I can't remember the cost now - sorry) and that appeared to solve the problem. There's a old post on HJ here about something similar:
www.honestjohn.co.uk/forum/post/index.htm?t=34134
Hope this helps
Edited by Dynamic Dave on 14/10/2008 at 13:18
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Thanks for that.
Does anyone know if an 'open circuit thermistor' is a temperature sensor? Peugeot seem to have a different name for things than the rest of the world!
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It's the engine coolant temperature sensor - the most likely source of a cold-running fault. Easy to swap - around £20.
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Thanks for the help. This forum is a gem.
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Our 306 did EXACTLY the same. It took me ages to find the fault which was the GREEN engine temp sensor (this car has 3 of them, but it is French afterall). Cost about £10 for a new one.
The sensor had an intermittent fault. It worked okay from cold and then would go "open circuit" for a couple of seconds, before working okay again. When it goes "open circuit", the ECU thinks the engine is cold and so over-fuels, which is why it revs-up. It was a horrible fault to find. I had tested the sensor out of the engine and convinced myself that it was okay. It was obviously only going faulty when it was screwed in to the head/thermostat housing.
I had refused to let the Peugot dealer try and sort this-out, as they wanted £70 just to read the ECU codes, and this was 6 or 7 years ago. I'm sure they would have had me for a new idle-control valve, but all the forums pointed-out that this was a high-mileage fault and our 306 has only done 42,000 now (V reg).
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Our 306 did EXACTLY the same. It took me ages to find the fault which was the GREEN engine temp sensor (this car has 3 of them but it is French afterall). Cost about £10 for a new one.
Just for anyone's future reference this was the part to blame. It was about £12-13 from my local Peugeot Dealer.
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