80 TDi Couple of probs/questions

[Marc97]

During a 3 hour drive today, I realised that it might not be the throttle position sensor.
When I change gear and the throttle revs itself, it then drops down slowly. Does this not mean that it has sensed the release of the pedal?
If so, the sensor is working, I am thinking that the problem might be pump/injector related, either the pump is not reacting to the release of the pedal due to some sticky mechanical part or one or more of the injectors are dumping more fuel than needed (leaking) into the bores which is then being burned resulting in the higher revs.
Whichever one of the 3 options it is, due to the cost of each part, trial and error isn't an option, the faulty item MUST be diagnosed.

[pcar964]

Marc,

No further forward, 99% sure it's the throttle pedal sensor.

Found this:
http://www.bba-reman.com/content.asp...ips_volkswagon

NO ACCELERATOR RESPONSE
AFFECTED MODELS :
Engine code: AHU, AFN 1.9 L TDI 66/81 KW
FAULT:
No accelerator response, engine only runs at idle speed. Fault entry: '777'-"sender for accelerator pedal position implausible signal".
CAUSE :
Water gets into the box for the ECU, contaminating ECU and connectors. The cause for the water entering the ECU box is a missing or incorrectly fitted seal.
SOLUTION:
Check, whether the seal ring is present or incorrectly fitted. If necessary fit or adjust the seal. Check the engine ECU and the plug for water or corrosion. Clean the parts or replace them if corroded.

Haven't had a chance to hunt for the ECU to check it, bloody cold outside and dark too early. Anyone care to tell me where it's located please?

Peter

[Marc97]

Marc,

NO ACCELERATOR RESPONSE
AFFECTED MODELS :
Engine code: AHU, AFN 1.9 L TDI 66/81 KW

Mines a 1z so wonder if its the same (more than likely eh?)

Haven't had a chance to get at the ECU to check it, bloody cold outside and dark too early.

I hear you mate, crap innit. Just been out to see if I can stop my alternator belt squeaking but couldn't work the tensioner out buts that another post.

Cheers, keep at it,

Marc.

[pcar964]

I hear you mate, crap innit. Just been out to see if I can stop my alternator belt squeaking but couldn't work the tensioner out buts that another post.

Cheers, keep at it,

Marc.

I've just had a quick look at auodata cd:



AC - Aircon compressor, Gen = Alternator, T = tensioner, CS = crankshaft, WP = water pump, PAS = power steering pump.

HTH

Still hunting for the ECU, anyone care to tell me where it's located please?

[Marc97]

Cheers for that Peter, but its the tensioning I can't figure ie, how to loosen it off so I can change the belt or how to tighten it so I can tell if I need a new belt.

[VW Techniker]

Hi all,

Just been reading thread and it sounds like you are suffering from faulty air mass meters, you need to check the imput signal to the ECU with an oscilloscope; serial data (or using code/live data reader) can be a little too slow to trace on a vehicle of that year... In my 15 years of working on VAG vehicles I think I have only changed about two Throttle Pedal Position Senders... They are very reliable.

Rob

[Marc97]

Thanks for that, I unplugged my MAF meter and the car was terrible.
From that, I concluded that it was working.

Cheers,

Marc.

[VW Techniker]

Yes it would on a TDI, its a critical input signal. But it has a 5v range and may only cause problems at certain points throughout the range. By disconnecting it you are giving a fixed value of 5v (or 450-550 mg/s) of air and causing the EGR valve to open... Not really a diagnostic proceedure you can rely on.

[Ally80]

Hi all,

Just been reading thread and it sounds like you are suffering from faulty air mass meters, you need to check the imput signal to the ECU with an oscilloscope; serial data (or using code/live data reader) can be a little too slow to trace on a vehicle of that year... In my 15 years of working on VAG vehicles I think I have only changed about two Throttle Pedal Position Senders... They are very reliable.

Rob

Hi Rob,
I replaced the air mass meter in April/May with a Pierburg unit from Audi (£138+vat) & the car was given a new lease of life(previously sluggish!) untill now,that is!! It does feel as if something is sticking,or an incorrect signal is being sent. Also I removed the pedal sender(to obtain part num)& after replacing it,the car behaved differently.Still getting the probs but,the revs aren't going or remaining as high now(was 3.5k to over 4k revs) but the lack of throttle after gear changes is happening more often.
Most annoying! Oh,do you happen to know where the ECU is situated in an M reg 80tdi estate? It's been suggested that water may have penetrated the housing!

Cheers

Ally

[pcar964]

Cheers for that Peter, but its the tensioning I can't figure ie, how to loosen it off so I can change the belt or how to tighten it so I can tell if I need a new belt.

Looks like an automatic tensioner. Start a new thread and ask.