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Hi,
Can anyone sugggest possible cause for 1.9tdi 2000 model A4 to be running with noticable power loss.Feels like no boost is being produced.Local garage has had it on the diagnostics machine but it did not show any faults in the log.
Any help would be much appreciated.
Steve
 

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Same problem on my 2.5 TDI. Changed the airflow meter, but did not get to the root of the problem.

I do not get sufficient boost. On a drive test, maximum was about 1600 mbar, while air flow was about 650 mg. This was in 5th, at 4000+ rpms. However, my mechanic says that I should be getting 2000 mbar and over 1000 mg in 3rd, at 3000 rpms. I don't even approach these values.

Occasionally, the turbo bypass valve would block open, in which case I totally lose boost pressure, and car runs like ****, having no power and topping at 2000-2500 rpms. Tested while car is sitting, the valve seems OK.

Next, I thought that the catalyst was clogged (had a major oil consumption problem before). So I tried cleaning it, but I noticed no improvement.

Another strange thing is that engine temperature usually stands at 78 degrees Celsius. Only when accelerating hard (as hard as the car would let me) up to 180 km/h it goes up to 90 degrees. This is not normal. Could the two problems be related?

I am now thinking of testing and adjusting the injection timing. If that does not cure it, then maybe I'll change the bypass valve. I have no other ideas.
 

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Hiya got similar problem myself.

A4 Tdi 1.9 Auto (1996)

Turbo cuts off after about 10-30 seconds of using it.
Comes back on after restarting car..
Loads of black soot and smoke.
Only giving about 50 miles for 10 pounds of fuel.
Speedo works occasionaly (if working when car started then will work until switched off and vice versa)

Recon'd injectors,
New Cat,
Changed air flow..

still same problem.
 

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hi, im a new member.
came across your topic and straight away thought of the airflow meter, happened to my ex A4 tdi. make sure what you fitted is not faulty...mine turned out to be faulty 3 times and they were all new!
regards.
 

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Guys ..

It may sound really obvoious.... Check your air filters!!

Yes MAF sensors are usually to blame for power loss and easily diag'd.

If you have a TDI kicking out plumes of smoke with initial power but tailing off, check your air filter.
 
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