1.9TDi troubles

[Lee]

Been away fro a few days to collect another car.

Just got my hands on a 90PS 1994 Audi 80 1.9TDI sedan. Lovely car in great nick apart from a slightly dangly front bumper which is nothing serious to sort. 123k miles but the interior and bodywork look like it has done a quarter of that.

Only real problem with the car is the engine:

When cold, engine fires first time but dies after 2 or 3 seconds..throttle input makes no difference. This process is repeated on several occasions until the engine fires and idles...but, throttle input makes no difference. I unplugged the MAF and hey-presto, throttle worked...prior to disconnecting the MAF throttle would only work after letting it idle for a good few minutes. I did notice some air in the return lines to the fuel filter when it was struggling to start so have tightened up all the clips and unions. Can't tell if that bit is sorted until I try it from cold tomorrow.

Rev the engine at standstill with the hood open and there is a little chirp from the turbo so I suspect the carbon-loaded oil has acted like grinding paste and fooked the bearings. Having said that, I took all hoses off and there is no axial play, only a bit of radial so we'll see if a good service cures that. One or 2 tapped are a tad noisy so maybe a couple of oil changes in the next 2000 miles will get some fresh lube everywhere.

It depserately needs a service so I will not be doing any VAG-COM logging yet. PLus all the belts need changing.

Noticed one funny thing, the vac hose that connects to the EGR valve that sits above the turbo had a ball bearing in it. Why would this be? Is it a previous bodge at a repair attempt. Replaced that hose to ensure it is unblocked.

Engine bay was completely caked in oil so have just spent all of this morning cleaning it down with Gunk to pinpoint the leak.

Car feels like it has about 30PS!!! It has no torque and as soon as it sees the slightest incline it dies! I know the car used to do a ton quite readily but I was having trouble coaxing it up to 70mph on the flat. Pulls ok in 1st and second but as soon as the load increases it just gives up. SOmetimes it feels like something is modulating or pulsing when holding it on part throttle driving down the road...as if the driver is squeezing and releasingt eh throttle at about 0.5 to 1Hz. Got one fault: "00575 - intake manifold pressure, 17-10 - Control Difference - Intermittent".
I need a WGFV anyway as one of the ports is damaged but not bad enough to stop it working properly.

So. Anyone had these lack of throttle at startup issues? Similar running faults or lack of power? How do I eliminate the various sensors and actuators?

How much is a new MAF for my new baby? How much would the turbo cost if it is FUBAR'ed

I have no problems fault finding on the S2 but I need a diesel guru!!

Thanks in advance, Lee

[Mihnea]

Lee, put that ball bearing back into the EGR hose. EGR is anti-mechanical (feeds the engine with exhaust gasses instead of fresh air) and the problem is that the EGR valve itself gets caked with carbon/soot and it sticks open. That might be your problem with the car not having any power, if you give it WOT and it dies, it might be because just when it needs air, it's breathing exhaust gasses instead of air...

Otherwise, congrats and take good care of it

Cheers,

Mihnea


PS: yeah, change the oil and give it WOT with VAG-Com, we'll figure out what's wrong...

[S2 Ant]

Might just be me but i cant find the MAF on ETKA for it...
If you can give me the part number i have an up to date price list so i can let you know the costs.

[s2avant]

@Ant,

You need to be looking at illustration 129-38. On diesels MAF's are nearly always shown with the airbox.

Depending on your chassis number it's either £75.10+VAT for an exchange one (8C-R-128402 onwards), or if it's the earlier type it's a more S2 like 373.03+VAT!!!

Plenty of discount to play with on these though so either MartynF or me can see you right with one.

As for the turbo, again chassis number related, it's either £602.07+VAT or £518.17+VAT eschange. Nowt to play with on these really although Martyn should be able to sort one out cheaper.

Ben

[Lee]

Lee, put that ball bearing back into the EGR hose.

Put the ball bearing back??? It fully blocked the hose! I figured it was put there to plug the hose to solve a problem. If it is meant to be there, why have the hose at all?

Cheers for the info guys. I will find out the PN of the MAF.

[Skull]

The MAF is expensive, around 400 eur. I think mihnea already said this: the lack of power is almost for sure the valve above the turbo, i dont know how it is named. I have just sealed the metal pipe that leads from the exaust manifold to this fooked valve. Also take the injectors to the nearest bosch service to clean them out. And the MAF, it is fooked for sure

Here is a pic

KAM marks the pipe that must be sealed and WTF marks the valve.



In the lower left corner you can see the bloody MAF!

[Doug_RS2]

Interesting - I have some oil on my airbox - obviously spraying out from that valve. I think I will block that vaccum pipe too - see if makes a difference

I also have black smoke out the back when WOT.

And when cruising at 85mph it feels liek the turbo is spinning up and slowing down - I am keeping the throttle in the same position

[Skull]

If you have oil ON the airbox, than the oil is coming from the internal cover of the hood if you have one. it gets really dirty. What WOT means? And, how the hell can i measure the pressure of the turbo? i connected a gauge to the little output before the intake manifold, but the gauge was like dead. i thought the gauge was broken, but i tried with 3 different! whatever you do, dont block the oil fumes pipe that gets into the turbo. i killed 3 seals, and i still have an oil leak, somewhere...

[Doug_RS2]

Oil, I think, is getting blown from the valve to the oil filter box - is this normal? Or does this mean the valve is fooked?

[Doug_RS2]

And Lee - I have those bubbles of air in the diesel fuel return pipe - is that normal?

[A6 AVANT]

And Lee - I have those bubbles of air in the diesel fuel return pipe - is that normal?

Lee/Doug, small bubbles is normal, I have not seen an audi/vw that doesn't. My Avant does (AFN) running not affected.
Lee, Your lack of power defo sounds like the MAF. Mine lost power on hills etc but diag threw no faults! Replaced MAF and away she wnet again!
HTH
Chris

[audiman]

The 80tdi uses a vane type MAF, unlike the Hot film normally used on later tdis. Check to see that the flap moves all the way and isnt sticky in its full travel, also check the voltage of the signal wire when moving the flap to make sure that the track inside isnt fooked.

As for the EGR valves, weld them shut and keep them shut, they get sooted up and stick open like Mihnea said, this causes massive lack of power and also plenty of black smoke. The vlaves are not cheap, 200 quid ish


Bubbles are normal, they all do it.

[Skull]

Doug: i pointed wit the red arrow where i have sealed the pipe. do it, and then you will see if the valve was the problem. btw.: where would that valve get the ol from? i pointed a little pipe with the blue arrow. where does it lead? i dont have that pipe, it is sealed wit a rubber tap.

[Skull]

and... mine doesent have bubbles at all!

[audiman]

All the ones i have ever worked on do, even the newer a4's/a6's do that.