Help...A6 Avant 1.9Tdi Sport 2002 Loss of Power

[bebecheekymonkey]

Help...anyone out there who can advise?

During a trip away with the family over the easter weekend, my car suddenly started to lose power (boost) when excellerating. It appeared that the car went into limp mode and i was unable to do more than 80 mph on the motorway and the car was very sluggish when pulling away. Power came in and out and it was difficult to drive.

Having sought some advice, i checked the MAF sensor and replaced this with a new one from GSF. However this still did not solve the problem.
Does anyone have any ideas what is causing this?

A mate brought along his diagnostic equipment and found that the maf worked at idle but as soon as we pulled away and the boost increased, the car lost power again as if it had gone into limp mode again.

Any ideas? Please... (car has done 78k miles)

Thanks.

 

[fjtwelve]

Try the N75 boost control valve.
Look for split hoses
Could be sticking actuator arm on the turbo
There are plenty of similar threads on the forum, have a look around

 

[maxlbrown]

Vag -com codes can any one shed light on these for bebcheekymonkey


Thursday, 12 April 2007, 21:20:19

VAG-COM Version: Release 409.1-US



Control Module Part Number: 038 906 019 CF

Component and/or Version: 1,9l R4 EDC 0000SG 1540

Software Coding: 00002

Work Shop Code: WSC 02325

Additional Info: WAUZZZ4B83N018778 AUZ5Z0B6297059

4 Faults Found:

17552 - Mass Air Flow Sensor (G70): Open or Short to Ground

P1144 - 35-10 - - - Intermittent

17564 - P1156 Manifold Absolute Pressure Sensor Circuit Open/Short To Ground

P1156 - 35-10 -

17569 - P1161 Manifold Temperature Sensor Circuit Open/Short to B+
P1161 - 35-10 -

18057 - Powertrain Data Bus: Missing Message from ABS Controller

P1649 - 35-00 - -

Ignore the ABS error we disconnected it to get error codes read from the engine ECU so was expected.

Sorry forgot we had real trouble getting the Engine ECU to read using VAG-com Kept reoprting to many comms errors. We had the same issue with auto enguineuity system. we finally got the codes above and cleared.

Also using auto enguinuity we found the MAF flow rate was 0 all the time.

This may be a duff 2nd MAF or broken cable. Any help would be appreciated.

regards

Max

 

[bebecheekymonkey]

Thanks to MaxBrown for his help and use of VAG-COM. The VAG-COM results showed above in MAX's thread indicate it may be the MAF again.

Since then, I have checked the MAF again with an identical working one borrowed from another car and still the same problem. The auto enginuity diagnostic still showed MAF reading "0". Checked the leads from the ECU to the MAF, this was ok.

Now working our way round the car and checking the N75 and hoses, etc.
I really hope its not the ECU as we had difficulty getting fault code readings with VAG-COM.

On the drive home back from MAXBROWN's there was no boost pressure until we went over 50 mph. Over this speed the Auto Enginuity showed it to be working fine and the car went back to normal again.

Anyone out there who can help us out with the VAG-COM fault codes shown above in MAX's thread. Your help is much appreciated.

 

[bebecheekymonkey]

Wooooohooooooooo......found the fault. Now fixed.

Since my last thread back in April, the problem with loss of power seemed to have sorted itself out. The car was working fine all through the summer. We even went up to the lake district and down to Cornwall in August without a hitch.

Then yesterday, after the car was serviced by an independant, the original fault came back. No power! Diagnostic showed a fault with the airmass meter again. This I thought was strange as the air mass meter had been changed in April.

However, I spent this afternoon looking and checking everything as I was convinced it was not the airmass meter again.

What a shock, I followed the wiring loom leading from the airmass meter and followed this around the back of the engine and to my horror saw that the wiring loom had melted from where it was touching the exhaust manifold! It was covered in thick black grease and was bearly visiable behind the engine.

The plastic sheath housing the wiring loom had gone and the dozen or so wires exposed. Two of these wires had snapped. I checked the colour coding of these two wires and it matched that connected to the airmass meter....Hence a zero reading for the airmass on the diagnostic machine and no power!

I soldered the two wires back together and taped them up sufficiently....and to my surprise, this solved the problem.

Took the car for a test drive and the power is unbelievable. There is so much more power/torque than before. It felt like a new car again!

Why on earth did Audi put a wiring loom next to the exhaust manifold? Doh!

Anyway, I'm glad its now all sorted .......finally...



Maxbrown - You were right about a possible broken wire. Only that we didn't find it the first time round as it was obscured round the back of the engine and covered in thick black engine oil and grease.