80 TDi Couple of probs/questions

Firstly, I'm a new member so hi all.
I bought a '95 (M) 80 TDi about a month ago, my first Audi TDi although I have owned a Coupe before.

Anyways, down to the nitty gritty, When I set off, as I press the clutch to change to second, the revs will go up and hold at about about 3500 - 4000 rpm for a second before they start to drop back down and when I've changed to second gear and put my foot back on the throttle, it either does nothing or is very un-responsive as if I'm barely pressing it, again, only for a couple of seconds, after which the car drives normally. This is an intermittent fault which only happens a couple of times a day but I would like to get to the bottom of it.

I'm also interested in fitting a 'tuning box' but have no idea whether my car is PD or non PD?????? Were PD pumps only fitted after a certain year??? Can anybody give me any idea what I need to look for to answer my question?

Car has 162000 miles on it, no idea when it was last serviced but seems to have plenty of power and is responsive (compared to the Astra TD it replaced!!!!), so I'm at a loss where to even think to start looking for a fault.

Cheers,

Marc.

Marc,

Did you find a solution to this problem? I have a very similar problem on my M Reg 80 1.9TDi Avant.

Another issue is that there is next to no power at low revs in first gear, then when the revs pickup the turbo cuts in causing wheel spin. Makes hill starts and pulling out of T junctions very difficult.

Any ideas anyone?

Thanks,

Peter

Hi, no I haven't managed to get to the bottom of this one.
I too sometimes have trouble pulling away but I think thats down to the same problem where the car just doesn't seem to respond at all to the throttle.
If I get it sorted, I'll be sure to post the solution.

Hi Marc,

That describes it really well. Pressing pedal results in nothing, then a sudden surge as turbo kicks in. Also experience it in other gears if I come of the throttle or coast, then apply throttle again - no power.

Lack of power when pulling away in first sometimes means steering is very heavy as if the power steering belt had snapped.

I hope we can find the cause and the solution.

Peter

Just a quick question.
When the car surges, does taking your foot off the accelerator actually do anything? I mean, does the car stop revving or does it carry on as if it was possessed?
The non responsive throttle pedal is usually preceded by unneccessarily high revs between gear changes.
I think I'll get an exorcist to have a look at mine lol.

I experience the non-responsive throttle pedal almost always in first gear when trying to pull away. Engine gives very little power and if I give it progressively more throttle, nothing happens until all of a sudden car takes off rapidly often spinning the wheels. Makes driving in slow moving traffic very difficult and almost dangerous.

As I said, happens in other gears too after coasting with clutch disengaged or lifting foot off throttle pedal to slow down.

The surge in revs is when changing gear, so foot is already off the throttle pedal, this is much more intermittent than the loss of power.

I have not experienced any connection between the surge in revs when changing gear being preceded by lack of power.

Quote:

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Originally Posted by pcar964

I have not experienced any connection between the surge in revs when changing gear being preceded by lack of power.

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Its the other way round for me and seems more related ie:
1st, surge in revs between changes
2nd, lack of power after change when releasing the clutch and getting back on the throttle.

As I said, luckily, it doesn't happen too often BUT, I can reprodude the problem on demand.

Push the throttle to the floor with 3 quick blips, revs rise to around 4000 and hold there for a couple of seconds (my foot is off the throttle at this point) then press throttle when it returns to idle. Result: no response.

Quote:

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Originally Posted by pcar964

I experience the non-responsive throttle pedal almost always in first gear when trying to pull away. Engine gives very little power and if I give it progressively more throttle, nothing happens until all of a sudden car takes off rapidly often spinning the wheels. Makes driving in slow moving traffic very difficult and almost dangerous.

As I said, happens in other gears too after coasting with clutch disengaged or lifting foot off throttle pedal to slow down.

The surge in revs is when changing gear, so foot is already off the throttle pedal, this is much more intermittent than the loss of power.

I have not experienced any connection between the surge in revs when changing gear being preceded by lack of power.

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I take it you never drove a diesel prior to this car, innit ? Thats common with TDI due to their relative high torque compared with a similar petrol engine. You will soon adjust your driving style as when releasing the clutch it needs a light blip and you are away, no need to accelerate and then quickly accelerating trough gears. Because of the torque, you will find its not necessary to downshift so often as with a petrol car ! Also you will see that its easyer to drive a manual diesel in slow moving traffic as the engine will pull in second or third at tick-over and returning better Mpg. I have trouble adjusting my driving style when i drive missus polo 1.4, i mean its either underreved or overreved and it takes about 5 min to adjust my usual heavy foot to the light featherweight acceleration of the polo. I often stall the polo when i drive off from a stand still but i never stall my diesel. When i need it to go slow- i use i light foot and when i wanna go fast i just boot- it.

Quote:

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Originally Posted by Marc97

Its the other way round for me and seems more related ie:
1st, surge in revs between changes
2nd, lack of power after change when releasing the clutch and getting back on the throttle.

As I said, luckily, it doesn't happen too often BUT, I can reprodude the problem on demand.

Push the throttle to the floor with 3 quick blips, revs rise to around 4000 and hold there for a couple of seconds (my foot is off the throttle at this point) then press throttle when it returns to idle. Result: no response.

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You, my friend, experience what its known as Turbo Lag and in your case could be accentuated by a sticky/slow raecting/sooted-up VNT mechanism, that is common with high milleage cars driven in heavy traffic or in coffin-dodger style...!

Thick mode again. Whats a VNT?

Thanks for the reply, I'll try and clean out the 'VNT' asap and report back.

PS, I have owned TD cars for quite a few years now and I am used to plenty of lag at low revs although this is my first TDi and my first electronic throttle car. The feel of the throttle is eerie in comparison to my other cars.

Thats is the variable vane mechanism (the moving fins inside a Garrett turbocharger) and with carbon build up it jams and may set a code in the memory. If your turbocharger is wastegated(KKK) then you may disregard this thread as its operates differently and if faulty you should check for a stuck open/close wastegate that will trigger a overboost/no boost code and one should check the vacuum hoses for splits and cracks leading to similar symptoms. Generally KKK turbochargers are a bit more reliable but the Garret ones are more common and easyer to tune and much cheaper...!

Cheers, my car has an actuator on the turbo so I guess that means its a KKK?
I have checked all vaccum pipes but they are all fine, I'll have a play with the actuator/wastegate and clean the wastegate hinge tommorow.
Will the overboost code remain on the ecu and stay as a fault?
Will it affect the car until it gets cleared?
Can I clear it by disconnecting the battery lol??? (well it is an old car, it might not have the same memory capacity as all the spritely younger cars :) )

Cheers Adam,

Marc.

Quote:

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Originally Posted by Marc97

Cheers, my car has an actuator on the turbo so I guess that means its a KKK?
I have checked all vaccum pipes but they are all fine, I'll have a play with the actuator/wastegate and clean the wastegate hinge tommorow.
Will the overboost code remain on the ecu and stay as a fault?
Will it affect the car until it gets cleared?
Can I clear it by disconnecting the battery lol??? (well it is an old car, it might not have the same memory capacity as all the spritely younger cars :) )

Cheers Adam,

Marc.

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They will stay logged in the memory until you disconect the memory. Newers models logs them onto a non volatile memory that will hold for a while(dont know how long). Turbo related faults will/may trigger Limp Mode and will clear as soon as you stop/start the engine again until the condition that make it reocurs.

So I can clear it by leaving the battery off for a couple of hours then.....WOOHOO.

:beerchug: mate.

Marc,

Our 80 TDi Audis do not have the variable vane technology turbos, our 90bhp engines have standard wastegate turbos.

Where did you read that it's a fly by wire throttle? I've driven a few of these like the V10 M5 and 996 & 997 Turbos and not found it to be a "weird feeling"


Adam,

I've driven many cars, diesels and petrol, turbos and nasp. Nothing has ever been intermitently so lacking in power when pulling away, so it's a fault, not my driving style.

Wish I had a code reader :p

Peter

Quote:

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Originally Posted by pcar964

Where did you read that it's a fly by wire throttle?

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My car doesn't have a throttle cable so I'm guessing it is a 'drive by wire' system.

PS, still not fixed!!!!

Hi Mark,I,(new member Ally80)found ,while surfing the net for answers ,that you are experiencing the same problems as myself regarding the strange behaviour of the engine management system on your audi 80 1.9 Tdi.I do know that it has nothing to do with the way your driving the vehicle.I've had my TDi estate for 6 years(done 130k)and now the thing's acting up with high revs between gear changes and some times no acceleration when pulling away at a junctions/roundabouts!! most annoying.I think that it could be the accelerator pedal sender/throttle position sensor acting up,not sending the proper signals,though not sure.If you do hear anything or find a remedy please let me know.
I was quoted £409+vat from Audi for this part, so I won't be buying one as part of my ilimination process.

Regards

Ally

Hi Ally,

Welcome to the group. Price of the throttle sensor is exhorbitant. Until Marc pointed out it was a fly by wire throttle, I hadn't known. With the injection pump being under a plastic cover I hadn't noticed the absence of a throttle cable - doh. Learn something new every day.

I have vag-com 409.1 and Audi-VWTool Version2.0.9.exe to read, reset and programme the ECU, what I don't have is a data cable to connect PC to the OBD connector.

If you or anyone else were able to lend me a cable or suggest where I can buy one cheap, or how to make one I will try and figure out what causes the problem. :1zhelp:

Peter

Quote:

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Originally Posted by pcar964

Hi Ally,

Welcome to the group. Price of the throttle sensor is exhorbitant. Until Marc pointed out it was a fly by wire throttle, I hadn't known. With the injection pump being under a plastic cover I hadn't noticed the absence of a throttle cable - doh. Learn something new every day.

I have vag-com 409.1 and Audi-VWTool Version2.0.9.exe to read, reset and programme the ECU, what I don't have is a data cable to connect PC to the OBD connector.

If you or anyone else were able to lend me a cable or suggest where I can buy one cheap, or how to make one I will try and figure out what causes the problem. :1zhelp:

Peter

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See ebay for cheap cables and forget about making your one as it will be hard work to debug the interface. See rosstech for how to resync your accelerator position sender with the ecu(diesel pump) and see if its changes into better. See tdi forum for more details. Do a search there using thee boolean search as usually the other one is not that accurate ! Remember that its not as good as the google search engine and dont give up, read trough the posts as its a interesting forum and yankees are quite happy to share info ! Good luck.

Adam,

You mean the forum at this site? http://tdiclub.com/

Been reading the faqs, sounds complex.

Found this cable on ebay, price is not too bad, but I'm a little way of dealing with a seller in China. If it doesn't work doubt I can get a refund.

What do you mean by hard work to debug the interface? Is't it just a cable with an 16 pin OBD-II connector on one end and an 9 pin serial on the other? Then all I need to know is which pins to connect. I make my own scart cables (proper ones using all pins) and network cables.

Was working on a Porsche 997 Turbo Tip earlier today, very nice, very fast :biglaugh:

Peter

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.

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

Quote:

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Originally Posted by pcar964

Marc,

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

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

Quote:

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Originally Posted by pcar964

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

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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.

Quote:

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Originally Posted by Marc97

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.

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

http://members.aol.com/pcar964/audi/audi80tdibelts.jpg

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?

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.

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

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

Cheers,

Marc.

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.

Quote:

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Originally Posted by 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

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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

Quote:

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Originally Posted by 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.

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

http://members.aol.com/pcar964/audi/audi80tdialt.jpg

Quote:

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Originally Posted by Marc97

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

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LOL.

Ta mate.

Hi there, been experiencing the same probs as yourself.I bought a brand new Accelerator Pedal Switch from ebay(£30),fitted it and this has solved my accelerating problems.The motor is now going like a rocket, chuffed to bits!!
Also informed member pcar964 of this fix.

Cheers

Ally 80

Quote:

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Originally Posted by 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.

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I dont believe the 1Z engine of the Audi 80 has a VNT type of turbine, which means "variable nozzle turbine". The Geometry of the turbo does not vary (it does in the AFN engine of the 1996-99 110bhp Audi A4, for example).
So, the vanes of the turbine only get damaged with carbon deposits due to low traffic and slow driving in other TDi (recent) engines.

However, i do experience an excessive "Decreasing load" when shifting gear, feeling that the ECU injects extra-fuel to sweeten the gear changed. I have to lift the right foot a bit before the clutch, otherwise i will experience an increase in revs while shifting gear.
My Seat Ibiza with AFN engine 110bhp, doesnt have this , and honestly goes sweeter. Something in bettween could be more useful. Thinking of an ECU remap to fix this and and a bit of extra power.

Cheers

Henrique

Portugal

Quote:

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Originally Posted by Marc97

Thick mode again. Whats a VNT?

Thanks for the reply, I'll try and clean out the 'VNT' asap and report back.

PS, I have owned TD cars for quite a few years now and I am used to plenty of lag at low revs although this is my first TDi and my first electronic throttle car. The feel of the throttle is eerie in comparison to my other cars.

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Quote:

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Originally Posted by pcar964

Hi Marc,

That describes it really well. Pressing pedal results in nothing, then a sudden surge as turbo kicks in. Also experience it in other gears if I come of the throttle or coast, then apply throttle again - no power.

Lack of power when pulling away in first sometimes means steering is very heavy as if the power steering belt had snapped.

I hope we can find the cause and the solution.

Peter

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Hi pcar964 and marc97, I currently have the exact same problem on my 1993 Audi 80 TDi Avant. Did you solve the problem in the end? Thanks

Quote:

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Originally Posted by motchy87

Hi pcar964 and marc97, I currently have the exact same problem on my 1993 Audi 80 TDi Avant. Did you solve the problem in the end? Thanks

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Yes, like ally80's post; new throttle position sensor solution solved it.

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