I am not sure if I have a problem with the MAf sensor on my 1996 Audi A4 1.9tdi (110) but perhaps the BR experts could tell.
Driving down the M3 and felt something go a bit strange under the bonnet - can\'t recall what it was but I know it just felt a bit wierd. After that there was very very minimal acceleration in 4th and 5th gears, diminished in 3rd but seemingly OK in 1st and 2nd. I timed (unscientifically ie looking at my watch) that on a flat stretch that it took 17 seconds to accelerate from 60-70mph in 4th!! The pedal would be flat against the floor but the revs and speed would not increase.
After I pulled off the m\'way I turned the car off for a minute and then carried on like nothing had happened.
Does this sound like the MAF or coould it be something altogether more sinister?
All advice welcomed
|
|
I have had the same problem with a 1997 Passat 110 tdi for 18 months now. The main dealer has not been able to solve it, boost pressure sensor and air mass meter changed but to no avail, wastegate seen to be working. It will always reset by switching off the ignition and run normally until it does it again. The turbo works fine until the problem occurs so an intermittent fault with a mechanical component seems unlikely. There is no sensor on the turbo so where could it be registering an over boost? I wondered if the variable vanes were sticking open but would this be detected by any sensor? VW diagnostics were no help. It is currently with an independent mechanic and has him baffled. Any suggestions anyone?
|
Bit of a long shot but I wonder if the problem is caused by oil contamination onto the elements of the MAF. I will have to check whether the following is applicable to VAG but I remember the Bosch systems which use a hot wire Mass meter used to briefly apply a significantly higher than normal sensing voltage to 'burn off' any contamination from the filaments. This may explain why all is ok after switching off. Oil contamination of the vauxhall mass meters is common especially if the condition and level of the oil is amiss. Off to read up on it!!
Andrew
Simplicate and add lightness!!
|
My sons 1998 Passat Tdi110 has exactly the same problem.
I have checked the vacuum pipes, turbo variable veins, changed the turbo vacuum control solenoid (located between the turbo & radiator) & changed the MAF sensor all to no avail.
I belive the problem lies within the ECU itself.
There is a known problem with early Bosch ECU's used on the 110 engines. (See www.bba-reman.com)
Bosch unfortunately combined the MAP (manifold absolute presure)
sensor into the ECU itself, on other cars I have had, this is a separate unit usually attached to the bulkhead & easily replaced.
You will find a rubber tube attached to the underneath of the plastic intake piping at the rear of the engine, before it connects to the inlet manifold - this goes straight to the MAP sensor in the ECU.
I just need a known good ECU to try, to test out my theory.
Any takers ?
|
My 97 Passat Tdi (110Bhp) had a flat spot in 3rd gear at about 2750 rpm. Changed the MAF sensor, problem solved.
|
|
|
@ Dieselnut, I finally managed to fix this with my '96 A4. Even though the error codes showed a MAP sensor fault it turned out that the MAF was giving the wrong readings..
You welcome to give my ECU a go if it will work with the Passat. My ECU has the part number of 028 906 021 CE and I don't know if they're interchangable.
I have heard that the plastic connector the pipe joins to at the ECU can begin to crack. Might be worth a look..
@ CM, you really need to get the ECU checked for faultcodes before you start replacing anything..
|
Thanks for the info Boris.
I swopped the MAF from my Tdi 90 Golf which runs ok, & it made no difference, so I have ruled that out.
I'll check the ECU part No when my son is over next.
Where about in the country are you, I'm in Crewe Cheshire.
Philip.
|
I'm in Milton Keynes Philip.
When I swapped my MAF (after 12000 miles of the problem) it didn't actually make much of a difference immdediatley, I did notice more response but the turbo still cut out. After a few hundred miles things got better and better until the problem finally cured itself.
I just can't explain that!!
|
|
|
|
|
|
See my previous post:
www.honestjohn.co.uk/forum/post/index.htm?v=e&t=13...8
---> turbo!
(A surging, loss of power on a previous model Passat TDi, which felt like fuel starvation in a petrol motor, turned out to be the wastegate contoller..)
|
|
My maf failed and I replaced it with a Mercedes part for the ML series. Its a Pierburg rather than a Bosch part and supposed to be more reliable, did the trick for me. Look on ebay for one, and check www.tdiclub.com for the exact part. Your current maf will fail at some point, so why dont you buy one and see if it is the problem, and then you will have a spare at worst. Also if you unclip the lead from the maf and your performance improves thats your problem!
|
|
|
Thats interesting re wastegate, but remember that the 110hp Passat doesn't have one. From Freds: " .... the A4 engines (and the A3 110hp engines) use a variable-geometry Garret VNT15 turbocharger. There is no wastegate, and all of the engine exhaust passes through the turbine all the time. When the engine is running slowly, a set of vanes inside the turbine housing move, to direct the exhaust gases through the turbine at a shallower angle but a higher speed; this causes the turbine to spin faster, ..." Source:www.tdiclub.com/TDIFAQ/TDiFAQ-1.htmlurbo compressor
|
Interesting Nortones.....that explains why you can clearly hear the turbo whining at teh tailpipe at idle - just a very faint whistle/whine.
I'd check all the vacuum hoses but I do fear an ECU fault.
My A4TDi has now developed a starting problem, not sure if it is fuel or immobiliser related though....it starts, then immediately stops. After 10-12 tries, it starts and runs just fine.
--
groups.msn.com/honestjohn - Pictures say a thousand words.....
Reply |
Report as offensive
| Link
|
|
|
|
Interesting that the 110bhp doesn't have a wastegate - the Passat I had the problem with was a '94 90bhp (non-variable geometry) TDi. (The controller was a cruciform shaped block on the engine bulkhead.)
|
|
|
|
|
![2018 Audi A4 1.4T FSI S Line 4dr S Tronic [Leather/Alc]](http://images.honestjohn.co.uk/imagecache/url/crop/90x60/https/cdn.uk.prod.group-mobility-trader.com/images/cas/fe14c138f4104a27ee466270f7eb32d4/65ca73c1ccfc5a090b4029cc9e3a973f.jpg)
