rjc98rjc98
06-10-2010, 06:11 PM
Hello all.
I've searched the forum high and low for possible causes/answers but no joy so far.
1999 facelift A4 tdi 90 AHU engine, 138k
Gradually, over a period of 12 months this problem has begun and got worse.
Car starts fine, every time, on the turn of the key no matter what the temperature or weather. Glow plug light on dash lights up for about 2 secs then goes out - which is the point I fire up the ignition. Starts clean all cylinders, no smoke.
After about 2 secs of idling normally the glow plug relay (the blue one, number 202) then clicks persistently for a variable length of time, and the engine seems to labour and idles erratically. When the relay stops clicking, the engine goes back to normal.
Then, when anything electrical is turned on, or if lights are turned on or brake pedal pressed, the clicking relay returns and the engine labours for a period of time. Revving the engine seems to help the problem and stop the relay clicking so much, but things have deteriorated to the point that if revs drop below 2000 on the motorway with headlights on, the clicking begins and all the dash display and headlights dim in time with the clicking and engine labouring.
I have no warning lights come on, and the car will do this even if hot and just restarted after a 100mile blat down the motorway.
So, is the likely culprit: Alternator, battery, glow plug relay or something else? I have recently replaced the coolant sensor and it made no difference.
Just after some ideas of what it could be before I take a look at it on the weekend.
Thanks in advance.
Robin
I've searched the forum high and low for possible causes/answers but no joy so far.
1999 facelift A4 tdi 90 AHU engine, 138k
Gradually, over a period of 12 months this problem has begun and got worse.
Car starts fine, every time, on the turn of the key no matter what the temperature or weather. Glow plug light on dash lights up for about 2 secs then goes out - which is the point I fire up the ignition. Starts clean all cylinders, no smoke.
After about 2 secs of idling normally the glow plug relay (the blue one, number 202) then clicks persistently for a variable length of time, and the engine seems to labour and idles erratically. When the relay stops clicking, the engine goes back to normal.
Then, when anything electrical is turned on, or if lights are turned on or brake pedal pressed, the clicking relay returns and the engine labours for a period of time. Revving the engine seems to help the problem and stop the relay clicking so much, but things have deteriorated to the point that if revs drop below 2000 on the motorway with headlights on, the clicking begins and all the dash display and headlights dim in time with the clicking and engine labouring.
I have no warning lights come on, and the car will do this even if hot and just restarted after a 100mile blat down the motorway.
So, is the likely culprit: Alternator, battery, glow plug relay or something else? I have recently replaced the coolant sensor and it made no difference.
Just after some ideas of what it could be before I take a look at it on the weekend.
Thanks in advance.
Robin