Passat TDi went into 'Limp Mode' whilst overtaking....
Discussion
I've just bought the car- 06 Passat Sport 2.0TDi, and as far as I can tell it has been properly maintained (FVWSH).
The only thing I can see needs doing is a slightly noisy wheel bearing.
I drove the car back from Stafford via Coventry to Cornwall yesterday at a relaxed cruise (circa 80-90) for most of the journey with no problems.
As I approached a large steep hill on the A38 past Exeter, I dropped it into 5th and slotted in at little over 2250rpm.
I then fully depressed the throttle, and withing 1-2 seconds of WOT, it died on me- very little power.
The glowplug light was flashing & the MFD had some sort of warning I didn't get a chance to read properly. Something about an engine malfunction...
I managed to coast it to a layby where I let it idle for a minute or so & decided to turn it off.
I turned it back on straight away & the car was out of 'limp mode' & happy to carry on. I did try to make it do it again, by dropping a cog & booting it but it hasn't done it since.
Will it store a fault code on the ECU, and has anyone got any idea what could have caused it?
A friend who works on VAG cars alot has asked me if I caught the brake pedal, but I don't think I did. He said he heard that the prake pedal can 'trip the ECU out' on the later Passats....
The only thing I can see needs doing is a slightly noisy wheel bearing.
I drove the car back from Stafford via Coventry to Cornwall yesterday at a relaxed cruise (circa 80-90) for most of the journey with no problems.
As I approached a large steep hill on the A38 past Exeter, I dropped it into 5th and slotted in at little over 2250rpm.
I then fully depressed the throttle, and withing 1-2 seconds of WOT, it died on me- very little power.
The glowplug light was flashing & the MFD had some sort of warning I didn't get a chance to read properly. Something about an engine malfunction...
I managed to coast it to a layby where I let it idle for a minute or so & decided to turn it off.
I turned it back on straight away & the car was out of 'limp mode' & happy to carry on. I did try to make it do it again, by dropping a cog & booting it but it hasn't done it since.
Will it store a fault code on the ECU, and has anyone got any idea what could have caused it?
A friend who works on VAG cars alot has asked me if I caught the brake pedal, but I don't think I did. He said he heard that the prake pedal can 'trip the ECU out' on the later Passats....
Edited by Vidal Baboon on Monday 15th February 09:50
I'm not sure it has the DPF fitted?
The car has been used for long journeys for most of it's life, so i'm doubtfull it could be that causing the problem.
I've done some reading on t'interweb and it would seem the engine sensed overboost and went into LM to protect itself.
I've yet to get the fault code read, but it ties in with me dropping down a gear & booting it. So, I decided to phone a couple of specialists.
One of which seems to think it'll need the turbo cleaning.
I asked if he meant the acuator & vacuum pipework including an N75(?) valve.
He said, no, the Turbos build up with Carbon & need cleaning.
It's the first time i've ever heard about cleaning a turbo to cure overboost.
They said, it's £150 to clean it, or about £750 for a new turbo. I assume it's a recon unit at that price...
Does the above ring true with anyone else?
The car has been used for long journeys for most of it's life, so i'm doubtfull it could be that causing the problem.
I've done some reading on t'interweb and it would seem the engine sensed overboost and went into LM to protect itself.
I've yet to get the fault code read, but it ties in with me dropping down a gear & booting it. So, I decided to phone a couple of specialists.
One of which seems to think it'll need the turbo cleaning.
I asked if he meant the acuator & vacuum pipework including an N75(?) valve.
He said, no, the Turbos build up with Carbon & need cleaning.
It's the first time i've ever heard about cleaning a turbo to cure overboost.
They said, it's £150 to clean it, or about £750 for a new turbo. I assume it's a recon unit at that price...
Does the above ring true with anyone else?
I'd say the only thing it does on that check list is pick up around 2200-2500rpm. It's smooth all the way & pulls progressivly to around 4000rpm.
I took it out last night & put in a little diesel additive as suggested on another VAG deisel specific forum. I also gave it a good thrashing & it seems like it's cleared it's throat- for now.
If it is likely to be the N75 valve, i'm guessing it'll throw up a fault code (P0299?)
How do you go about cleaning the N75 valve? Also, someone has suggesting wiping the fault code memory, which may also help...
I took it out last night & put in a little diesel additive as suggested on another VAG deisel specific forum. I also gave it a good thrashing & it seems like it's cleared it's throat- for now.
If it is likely to be the N75 valve, i'm guessing it'll throw up a fault code (P0299?)
How do you go about cleaning the N75 valve? Also, someone has suggesting wiping the fault code memory, which may also help...
I've had my 03 Alhambra TDi go into limp mode once before.
I was towing and had just booted it on a uphill section of dual carriageway to get past a slower vehicle.
Once it had reached the flat and I backed off and then put my foot down again there was nothing.
I pulled over turned off and then on and it was till in limp mode. I drove for another mile and it didn't clear so I pulled over and called the RAC. I can't remember exactly what the fault was but he said it was reading that it had gone into limp mode to protect the engine. It migh have been from overboost. He had a look for leaking pipes or anything loose, put it all back together and then started it up. It was all fine. It then towed fine for another 50 miles home.
I was towing and had just booted it on a uphill section of dual carriageway to get past a slower vehicle.
Once it had reached the flat and I backed off and then put my foot down again there was nothing.
I pulled over turned off and then on and it was till in limp mode. I drove for another mile and it didn't clear so I pulled over and called the RAC. I can't remember exactly what the fault was but he said it was reading that it had gone into limp mode to protect the engine. It migh have been from overboost. He had a look for leaking pipes or anything loose, put it all back together and then started it up. It was all fine. It then towed fine for another 50 miles home.
Vidal Baboon said:
Had the codes read by a mate.
P0234 boost pressure exceeded
So it was overboosting then.P0234 boost pressure exceeded
Vidal Baboon said:
The faults have been cleared down now. Will popping fuel system cleaner damage anything in the system?
No not really, have seen someone make a jaguar high pressure pump fail by puting 4 or 5 tins of cleaner in with hardly any fuel in the tank, other than that no.Edited by Tame Technician on Tuesday 16th February 19:41
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