MAF/Turbo Issues?

[Typhoeus]

Hi

I have a 1995 Audi80 tdi and suffering similar problems

The cars power tops out when it hits 70mph and then picks up again if you de-accelerate and pump the pedal and then ease back on ever so gently.

Also same happens if you hit an incline when doing about 70mph(2600 rpm)

The car has done 205k miles, a lot i know but still, this problem should still be fixable.

My local Audi dealer said it might/might not be the MAF, as he said if it was then i would be getting low power throughout the rev range and throughout the gears? Is this true ?

Thing is this happened a lot recently, getting worse. Then all of a sudden it went. A few days later, back to the same problems.

I don't want to spend money getting Audi to diagnose it as they may not be correct, as i have read from previous threads.

I am tempted to replace the MAF but then if it is nto at fault i am stuck.

Seeing as the car is old and i am skint, what does anyone recommend ?

Many thanks in advance

[scotty33]

My 98 passat tdi has MAF problems, I find it runs well sometimes, but really low on power WHEN the fault 'kicks in'. The parts place I use suggested unplugging the maf, when it is bad.
Unplugged, I find the car runs normally, just down on power a bit compared to normal (limp mode), but much better than with a bad maf. I don't know if the same applies to your 80, but it costs nothing to try!
MAF symptoms can vary, before I bought my car, the MAF was faulty, it had no power anywhere, and it smoked a lot. New maf was fitted before I bought the car.
When this MAF failed I had no power until the revs reached 2300, then car ran normally (but in limp mode).
The 'new' maf I bought off E bay seems to be a cheap remanufactured item, and the symptoms are intermittent, you can be driving along normally , then the power just dies off.
If the MAF is faulty, I suggest you make sure you get a genuine Bosch or Pierburg part.

[Typhoeus]

Thanks for the reply

I shall try unplugging the MAF for my journey home and see how it goes.

Any other suggestions would be welcomed.

Oh, i was told by one guy that it could be a boost control valve? Seems to be many problems and cures from similar symptoms, which is why i need to make sure i get the correct cure before i spend what little cash i have :-)

Cheers

[scotty33]

You could try checking for ECU fault codes, a fault with the maf or boost valve should show up. See if there is anyone near you with Vag com?
On my car,the boost valve is located at the front of the engine on a little bracket by the timing belt cover, on the same side as the turbo. I had mine apart trying to diagnose my MAF issues, it was full of oil! Even if the valve itself is clear, the lines can become filled with oil.
There is another similar problem with a line going to the ecu becoming blocked with oil, I'm not sure whether your model has this. It's worth checking these things out first before changing parts.

[Typhoeus]

Thanks for the reply, Scotty33

I tested the MAF by disconnecting it and it went into Limp mode, i could not get above 40mph. I pulled over, reconnected it and it was back to how it was.

I then cleaned out loads of lines over the weekend, not anything excessive in them really.

Also notices a small pinhole in the top of the turbo pressure unit, which had oil coming out of it. I soldered this up and applied some liquid metal, which seemed to help.

Now the issue is this ;

When i accelerate in any gear and hit just under 3000RPM the turbo whistle 'pulses' on and off. As it does the car pulls when whistling and drops off when not. This happens every second, so very noticeable. Also, if i am doing just under 3000RPM in 5th, approx 75MPH and hit an incline the car starts 'pulsing' again and the turbo whistles on and off every second or so.

I have been offered a new turbo unit, well a second hand one, off a 110k'er , bearing in mind mine is 210k, for £100 and a mate will fit it for another £100. What i don't want is to go to this time and expense only to find that it is some sort of boost sensor or something.

Cheers

[scotty33]

I don't know what the symptoms you are having relate to. It seems like maybe the waste gate is opening and closing?
I would advise against forking out for a turbo, until you know that is the problem. There are a number of reasons that a tdi won't make boost besides the turbo. It would probably be worth finding somebody with Vag com to check fault codes.

[Eshrules]

have you had the car fault read? without this, you're working blind, it could be anything, vagcom would be inavluable in identifying the fault

[Lex Luthor]

Also notices a small pinhole in the top of the turbo pressure unit, which had oil coming out of it. I soldered this up and applied some liquid metal, which seemed to help.

Was this hole the result of corrosion or is it the bleed hole for the back of the diaphragm ? If it was the bleed hole then the vacuum actuator will not work correctly.
Have you a photo ?

[audijay73]

if it isnt any of above try taking actuator off its a fidly job but give it a clean you can pump it in and out with a football pump mine was full off oily liquid when putting back together leave small circlip on wastegate off what i found that adjusting wastegate by half turn on threaded bar towards front of car brings turbo in earlier or stronger and vice versa give it a go good luck