TDI start up.

Automatic

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Now and again the glow plug light on my dash will illuminate for a good 8 – 12 seconds. Whilst doing this if i wait for the light to go out before starting the car it will rev it’s self up violently to 2500 rpm or more for a good few seconds before eventually settling down to idle.

Now the car seems to be doing this on random warm starts after short trips too. I’ve read in the owner’s manual that I should never start the car in this manner intentionally, as well as making you look & sound like a plank behind the wheel.

Is this a common problem that points to a particular fault?
 
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Hi mate

I have the same problem. It comes and goes.

The glow light flashes on mine and indeed revs to 2000 for a few seconds before dropping to normal idling speed. Does it from cold or warm.

I have yet to work out what it is. I have no fault codes etc.

I even cleaned out the manifold flap etc, checked pressure converter system (N18, N285 valves that run the antishudder and egr etc) and have yet to find a problem. It is indeed bizzare

John
 
Thanks for that at least i know im not alone. Very strange phenomenon and yes sometime it does it without the lengthy glow plug display. I hope it doesn’t end up damaging anything and defo wish it would stop making me look like super noob in busy car parks !!
 
I have found out what causes this.

I had intermittent faults on the coolant temp sender.

1 Fault Found
17664 - Engine Coolant Temp Sensor (G62): Open or Short to Plus
P1256 - 35-10 - - - Intermittent

If this occurs at start up the engine doesnt get the info it needs, so it keeps the glow plugs on and revs the engine up to 2000rpm.

Possible Symptoms
Difficulties with starting a cold engine.
Diesel: an indication is extreme long time burning time of the glow indication light.
Starting the engine when engine is warmish or warm, idle rpm immediately is 1200 - 3000 rpm.
RPM at idle is irregular.
With all engine temperatures seldom idle rpm will vary between 900 - 1000 rpm.
With engine warm (90 °C) the engine temperature suddenly drops (70 °C) and slowly comes back to 90 °C.
Bad acceleration during warming up.
Possible Causes
Wiring and/or connections faulty
Engine Coolant Temperature Sensor (G62) faulty
Possible Solutions
Check wiring and connections
Check / Replace Engine Coolant Temperature Sensor (G62)

So you may want to replace your coolant temp sender.
 
Damn !! ALL this grief from a dodgy thermo? absolutely crazy. I have most symtoms bar the 90 down to 70c then back again and once over the inital rev up it's idle's perfectly fine. But i guess the other stuff will show soon so I'll look into having the items replaced. Possibly at RAC london as they're supposed to be good.

Thanks for you help, would never have gotten to the bottom of this my self.
 
Hi all, just found this thread under a search for '17664' as this is the only fault code my 1.4tdi has thrown up on my first ever use of vag-com. My symptoms are exactly the same as you guys- very long pre heat followed by eye wateringly high rpm startup and associated big end knock for 1-2 seconds before the oil gets around.

Found a replacement on ebay (part number is: 059 919 501A by the way) for £2.50 inc p&p. Bargain! Will report back once it arrives and I've fitted it. Does anyone know where it goes by the way?
 
Yeah their talking about replacing that item right here http://www.a2oc.net/forum/showthread.php?14256-1-4-TDI-starting-problem

And there's a pic of the item in the engine bay here: http://www.a2oc.net/forum/showpost.p...5&postcount=17

I still haven't gotten around to sorting mine, all i do when the glow plugs go barmby is leave well alone until the glow light has been about for about 20 seconds before starting and it's fine.

Still i''d like to get it sorted all the same.

Ok, cheers for that. Found it and then realised from the above threads that there are two types, 2 and four pin. I've ordered four pin flavour and after eventually managing to prise the bloody thing off the sensor itself found that I do indeed have four pins, so that was a bit of luck...
 
Ok, cheers for that. Found it and then realised from the above threads that there are two types, 2 and four pin. I've ordered four pin flavour and after eventually managing to prise the bloody thing off the sensor itself found that I do indeed have four pins, so that was a bit of luck...

Hi all, just a quick update- fitted the new temp sensor this afternoon. Bit tricky to get it to go in far enough to fit the holding clip, but I got there eventually.

Started her up- nice gentle idle, normal steady temperature rise and no leaks. Also cleared the fault code out and re-scanned it. Fault code no longer present. Result, hopefully!

Think the vag-com unit has paid for itself already :)
 
Ok please let me know if that annoying glow plug illume comes back any time soon. Also was coolant loss - leaking a major issue? if so i may ask my garage to do it.

Thanks for the update.
 
The preheat Amber light is back to the way it was pre faulty sensor I.e. 2-3 seconds depending on outside temperature. The coolant loss was minor and I just topped the reservoir up with antifreeze. Its a fairly simple job that just requires a little patience to get the old one out and the new one in...
 
Raising a thread from the dead!

I had a few incidents of the raised rpm at startup, also noticed my temp gauge only got up to 80 deg, used to all previous Audi sitting at 90. Scanned using vagcom and found I had code 17664.

I have now replaced the sensor. Now hits 90 deg, code not come back, hopefully no more revving incidents :)

Looking forward to seeing if the car drives better tomorrow.

Does anyone know how to check the old sensor?

I bought the sensor from TPS as I wanted original parts, pretty expensive at £41 including a new oring and clip.

Hope the above is helpful in confirming the fix.

Cheers Andy
 
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