A6TDi Tip same old same old.....

[fortontech]

Hi Guys

1998 2.5 150PS TDi with Tiptronic - 180k miles
New MAF

The same song that many are singing on this forum - lack of power, actually a 'dissapearance' of power, joining m/ways, hills and gradients etc etc....
One strange twist on this is that, once in 'limp mode' the vehicle power will 'return' and accelerate normally if the speed control buttons are used...... anybody help ?

Thanks in advance for all replies.


Alex

[white.akita]

i bought a 1999 a6 2.5tdi tiptronic a few weeks ago that has been chipped to 180bhp but the car pulls in 1st 2nd and 3rd like its got 100bhp !
it is definately not my maf either, im getting the gearbox oil changed in a few weeks time to see if that helps.
so im eagerly awaiting any feedback on these matters.

[pyates666]

I had similar problems with my 2003 1.9tdi TIP.Started with excess smoke and fuel consumption and eventually caused it to go into 'safe mode' several times.Was due to a split Turbo pipe.

[fortontech]

By 'speed control' I mean the stalk mounted cruise control of course - weird that throttle reaction is better via this than with the throttle pedal, does this point to a faulty position sensor perhaps ?

cheers

Alex

[dandam]

My 2.5TDi quattro manual used to do it a lot, changed the air mass meter and it definitely improved, then put some diesel cleaner in it and changed the coolant temperature sender on the engine and is now perfect, hasn't done limp mode in the past 2 months.

Was told that the temperature sender can send false messages to the ECU, so not sure if it was that or that the diesel cleaner has helped - but everything seems good now.

[white.akita]

my temperature does not hit 90 degrees untill ive drove 10 miles, is this normal ?
i thought it may need a new thermostat, but could it be the coolant temperature sender ?

[dandam]

my temperature does not hit 90 degrees untill ive drove 10 miles, is this normal ?
i thought it may need a new thermostat, but could it be the coolant temperature sender ?

I think this is fairly normal, but the sensor could still be sending the wrong message to the ECU, but the correct message to the dash guages

[white.akita]

so could the coolant temperature sensor make my car feel like it has lost 50 bhp ?
the strange thing is my power loss is only in the first 3 gears, it pulls quite well in 4th and 5th !

[ashtop]

Hi, first post so be patient,
I'm following this thread with an interest and also read other threads as have similar problems.

I have an A6 2.5 TDI, an oldish model 2001 pre face lift 150bhp mileage is high 160k but service book is good and the car drives and feels very good for its age and mileage.

The problem i'm having is the 3000rpm power loss on hills, car will not accelerate past 3000rpm. the problem will reset itself after a minute or so.
The problem first surfaced overtaking a lorry about 2 years ago, it was quite scary at the time and looking back signalled the start of the power loss problems, this problem has got more severe with time. I have recently changed the Mass meter for a replacement bosch part and this has really improved the problem, i am still getting power loss but a lot less often.

A few people have offered ideas, the local specialist thinks the diesel pump is on the way out (an expensive fix i know). some people are stripping the turbo down and cleaning the VNT and internals. I see on this thread the temp sender is being replaced (i like this idea as involves the least work)

anyway any help or ideas is greatly welcome and appreciated

Regards

Newbie

[snapdragon]

Check out my pics here...is this your engine?
https://www.vwaudiforum.co.uk/forum/s...ead.php?t=8935


With the engine idling, try pulling the thin vacuum pipe off the EGR valve, you should hear it snap shut inside the shiny metal dome which houses the diaphragm, you may need to try it a few times to pick up the sound, then leave the pipe off and plug the pipe with something like a bit of artist's paintbrush handle or knitting needle. Sometimes the EGR can be kept open by a faulty vacuum control solenoid.

Also, check the one way valve which is mounted on the bulkhead at the back of the engine compartment near the main vacuum pipe junction.
It is a small plastic thing, half black and half white. It has a thin pipe pushed on each side. Make sure you remember which way it is installed! Take it off and make sure you can easily blow through it in one direction.