406 2.1tdi

[LeighJ]

I have a problem with my 406 R reg 2.1tdi.

It intermittently revs up and down of it's own accord and there is no pattern with regards to the ambient conditons or if the air con is on or off.

It happens anytime and has been going on for many months.

2 electronic diagnosis have found no fault......has anyone else had this problem or know what the likely cause is.........one garage though it was the potentiometer but the electronic diagnosis revealed nothing.

Thew engine runs smoothly on motorway runs but goes erratic in town which becomes dangerous in slow traffic.

[406hdi]

air entering your fuel system could give the problems you discribe.check the seals and unions from the filter to the injectors.i had the same problem with a 309 and that turned out to be a cracked pipe on the "thingy" on the back of the engine that warmed the fuel.hope this is some help,gareth

[andy504]

An air leak is definately going to give you those symptoms but another common thing on 2.1's that'll also give you the same problems is the coolant temp sensor on the thermostat housing, i can't remember if it's the blue one or the green one but i think it's the blue one.

Regards Andy

[macaroni]

I had this problem on mine and it is definitely the coolant temp sensor. It is the green plug located on the thermostat housing on the right of the engine (looking from the front bumper).

It is about £10 from Peugeot and is a 10 minute job. Just don't do what I did and unscrew it after a long drive and scald your hand!!

I had 3 goes on a Peugeot diagnostic machine before it was spotted - useless dealers.

[andy504]

now now, not all of us dealer types are useless!!

Andy504

[macaroni]

I didn't mean to offend anyone, but I have had dreadful experiences at Peugeot dealers in Harrogate, London, Redhill and Crawley. So that pretty much covers most of the country.

If you are a good one, you are rare. Believe me.

[504gld]

I'm not so sure all Peugeot dealers are bad, just they dont make any money out of 'old bangers'. Trouble to find microfisches and the like isn't putting pounds in the bank. I think Andrew 104ZS would disagree as his dealer fixed the 104 with no charge. My dealers in Poole dont seemed to bothered to look stuff up, just give you Dean Hunters card, and Fussell Wadman Devizes who I use will look on the computer if you give them a part number, but not much else.

Anybody got a full 504 diesel parts book, I use the 1968 petrol one on www.504.org but it doesn't cover everything I need. Dean is helpfull and very well stocked but sometimes a bit too expensive for everything, when your rebuilding a car and a budget has to be kept to, but doesn't mean I havent spend hundreds of pounds with him!

[LeighJ]

Thank you kind people....i will try the sensor first......but when it comes to finding a leak in the air pipework/ducts can this be measured on a vacuum gauge ?

I will only say that the dealer I tried only had some young apprentice who didn't know what he was doing.....still they never charged me when I queried their findings.......the backstreet mechanic i found had some flash Snap On electronic diagnosis kit...but the weird thing was it found a potentiometer fault one day...the next it found nothing......

I will try the coolant sensor, but how can this be linked to a fuel injection system Some weird French logic ?

I will Let you know how it goes !!!


;D