The idle speed of my Peugeot 406 HDI (1999, 68,000 miles) will not drop below 1000 RPM making driving difficult in slow moving traffic. The local Peugeot agent is unable to help despite charging £70 for connecting it to their diagnostic computer.
Any ideas please?
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Honest John has suggested that it may be a blocked or malfunctioning EGR valve.
Would this be a likely cause, and approximately how much would it cost to replace?
Thanks
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BT
I'll never disagree with HJ [he might send the boys round...] but I can't see an immediately obvious link between your idle problem and the EGR.
HDi idle is controlled by the ECU - and it's a very tightly controlled system. Two things that can affect the normally ultra-precise 780 rpm idle speed are the coolant temperature sensor and the vehicle speed sensor.
I'd have hoped that a dealer could have seen any problems in those areas during a diagnostic; but.....?
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I have a 406 XU 7 petrol and I think it idles too quickly but I have no way of knowing what the correct idle revs should be.
Should it be like the diesel engine with 780 rpm?
Is the problem likely to be the same as with the diesel engine i.e. coolant temp sensor or vehicle speed sensor?
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i find the easiest way to see if you have a correctly functioning speed senser is to let the car tick over and physically push the car 3 feet forward,if the revs rise the speed senser is working
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starcott
The XU7 comes in various flavours with 8 or 16 valves and year-to-year variations etc. The engine code is LF-?; have a look in the VIN number for the missing letter.
As a general rule; PSA petrols idle at 850; or 950 with the air-con on. It's got an ECU-controlled idle system; but they're air-flow valves - nowhere near as precise as the iron grip of an HDi's fuelling control. I've seen one of those stay rigidly on 768 revs - no mattter what you threw at it.
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I checked the speed sensor by rolling the car forwards (as suggested by bell boy) and the revs did rise, so it looks like that is working ok. After looking in the Haynes manual, it appears that the coolant temperature sensor can only be tested by a Peugeot dealer using specialist equipment.
Looks like I will have to take it to a different dealer. Thanks for the help.
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I have checked the idle speed on my petrol 406 and it is about 1150 rpm. Switching air conditioning on does not seem to make any difference.
Is the problem still likely to be the temp sensor?
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starcott
This is getting a very messed up thread. The advice to the OP was specific to a '99 diesel HDi.
There could be many different reasons for a petrol one idling at an incorrect speed; without the exact year and engine code, there's no way of even telling what system of idle control it's using. PSA use many different suppliers of management components and they all do it their own way.
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