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Discussion Starter · #1 ·
I have a 2001 GT Tdi 110 with the familiar limp mode problem when pushing hard @ approx 3000 rpm. I know people have posted that swapping the maf has increased performance when the car has been feeling generally slow but has anybody cured the limp mode problem by swapping the maf ?  
 

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I've not heard of a faulty MAF causing limp mode.Is your car chipped/remapped?
Its more likely to be your MAP sensor triggering the limp mode. If I recall correctly, you can swap the MAP sensor with the "3 bar" version to prevent Limp mode. I cant for the life of me recall which car this is off though. Ill look into it for you.
 

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Does the car just go gutless at 3,000rpm then you change gear and it pulls hard to 3,000rpm then go gutless again?

If it does its the MAF, try unplugging it (temporarily) and drive it up the road and see if it runs any better.

Put a new MAF in mine when I got it and it went from being a diesel tractor to a rocket ship!

If its limp home mode surely the ECU light will come up on the dash and it will just run slow in any gear after it has cut in...
 

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Discussion Starter · #4 ·
It's totally standard no mods etc.. It goes into limp mode and stays there in any gear till engine restarted and hence ecu reset. When put into limp mode never get a light on the dash. If i take it really slowy up to 3000rpm it will sometimes(though not always) be ok and power up to 120mph though usually under quick accelartion will limp at 3000rpm and then top speed only 80mph, which sounded a bit like (to a non mechanic) it could be a faulty air reading ? Sudden flow of air as opposed to steady ??

Started happening about two months after i got it and went on the diagnostic machine i think they replaced a heat sensor (i know they had to remove the bumper to get at it). Ok then for couple of weeks but then fell outside the three month warranty.
 

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Hmmm unsure on that one then.

If you want to omit the MAF try disconnecting it as said before and run it to see if it goes into limp mode. It might be possible to do that for other sensors too but don't hold me to that. I know with the MAF if its disconnected then the ECU just assumes a stock (safe) reading for it and keeps the engine running. That is why disconnecting a very faulty MAF will make the car run better.

I'm sure others may be able to give you some other things to check soon
 

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I have a similar problem on my 115 tdi Bora, after about 20 secs of full throttle it goes into limp home mode. A typical example is doing 70 on the motorway flooring the throttle, by the tim I hit 90ish I loose all boost (limp home mode). As mentioned in the previous post there isn't any warning light, I then have to turn off the ignition and all is well again.

The car is very sluggish above 3000 rpm but I assumed this was because of the torque tailing off and the general nature of a diesel engine, it has been like this since buying the car a couple of months ago.

My local garage, not a main dealer did a fault code test and it said there was a intermitant boost fault, the garage reckon this is caused by the vanes on the turbo seizing (VW tdi turbos have mechanically adjustable vanes that adjust their angle dependant on the speed it is running to give better boost / economy). The garage seems to think it is a common fault and they have seen it before. Apparantly the vanes just need cleaning from all the crap that goes through the turbo. He has suggested I try a remap as the boost limits will be raised therefore stopping the limp home mode. But I would like to know what is wrong as opposed to turning the warnings off !!

Has anyone heard of this before?

I will try unplugging the MAF and see if it still happens, I was going to change it to a PD 130 one anyway. Fingers crossed....
 

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it sounds like theres some confusion about the limp mode here!

the limp mode is not a symptom of a fault, its the remedy of a fault(if bad enuf) for the benefit of the driver!

I've not heard of a faulty MAF causing limp mode.
If your car is in limp mode, then IT IS because a component(maf) is faulty and unable to supply a useable signal

The action to take at this point, is to replace the faulty component, which the ecu will have logged.
 

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The only problem is that the ECU says there is an intermitant boost fault which could be a number of sensors / components. We are trying to ascertain which component / sensor is causing this.

The car goes into limp mode when the ecu receives a signal out of its tolerance to prevent potential damage
 

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It's totally standard no mods etc.. It goes into limp mode and stays there in any gear till engine restarted and hence ecu reset. When put into limp mode never get a light on the dash. If i take it really slowy up to 3000rpm it will sometimes(though not always) be ok and power up to 120mph though usually under quick accelartion will limp at 3000rpm and then top speed only 80mph, which sounded a bit like (to a non mechanic) it could be a faulty air reading ? Sudden flow of air as opposed to steady ??

Started happening about two months after i got it and went on the diagnostic machine i think they replaced a heat sensor (i know they had to remove the bumper to get at it). Ok then for couple of weeks but then fell outside the three month warranty.
Thats the same prob Craig_GSI and myself have, we think it's the N75 Boost Valve. I have noticed if I get up to 80 in 4th, it's fine - just give it a few revs every so often and it seems ok! Think Craig's problem is more chronic than mine though.
 

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I don't want to alarm you, but mine had the same problem when I bought it 10k ago. It spent 2 weeks at a diesel specialists for them to eventually say 'we've changed all the sensors and it still don't work'. Then the garage where I bought it from took it to VW who changed the turbo,exhaust manifold and the lamda sensor again. Luckily it was under warrranty, and I haven't had the problem since. It may be worth taking to VW and asking them to take a look into it?

Also,have you checked the condition of all of the turbo pipes to check for cracks? These can cause intermittnet problems too.
 

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When I got my Golf TDI 90s christmas before last I had the same problem, the guy from the garage reconed it was the CAT, so he changed the cat and this did not fix the problem, then he changed the MAF, this didnt seem to solve it either, the problem persisted into the spring and then he changed the MAF again, this time this seemed to solve the problem, until recently, well just before christam last year that is and its intermittenly happening again.

Dod anyone manage to get to the bottom of what causes this, i do not get any codes on VAGCOM, no lights on the dash, loose boost betwen 3-4000 Rpm and an engine reset will fix the problem temporarily.

it is possible that the guy at the garage gave me a reconditioned MAF the first time and then a new one the second time and now its buggered again... seems unlikely...
 

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Discussion Starter · #12 ·
I originally started this post and have never really got to the bottom of it, despite returning to the dealer for a VAGCOM test which showed no problems I have also tried a couple of MAFS. First an import one which did seem to work for a while but caused the car to hesitate occasionally and then began to limp mode a bit but not as much as the first one. I then got a brand new VW one which stopped the hesitation but after a while also started to limp mode, so back to square one but i guess can rule out the MAF as the main problem.

After reading various posts on here about sticking turbo vanes i wondered if it could be something along these lines. I noticed that it started a few weeks after a had the car so began to wonder if it was my driving style that was adding to the way the turbo stuck(If this is what it was) ! It always used to limp at around 80Mph or 3000RPM, my drive to work is about 18 miles and in that drive i was never hitting more than 60mph due to B roads and congested motorway etc so never nearing the 3000RPM for many days and hardly ever taking it for a blast as the limp mode was hacking me off. What i decided to do was exerise (if this is possible) the turbo if you like by making a concerted effort to take it past 60MPH every day (There is a two mile stretch of motorway where i can achive this most days) I started every day taking to just below the limit it always limped so 75MPH and continued to do this for a couple of weeks. I then began to push the 80MPH (Limp zone ) for a few weeks before trying 90MPH. Previously it would always limp but now I can take it past 90MPH without limping. I wouldn't like to claim i had sorted it but it has only limped once in the past three months(When pushing hard up a steep hill).

Would be grateful to hear from anyone who can identfy with anything i've put above ?
 

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There must be some one who has solved the limp mode problem

It cannot be true that everyone on here who has had this problem has never got it fixed, !!!
 

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My understanding of Limp mode having experience it before in my lupo is that a component is at fault and the ecu is protecting it self, it could be an intermittent fault and your driving style that makes your motor act like this. My lupo struggle to achieve any sort of speed past 60mph and i suppose that i was just lucky that it wasn't intermittent it was an exhaust problem and a ignition fault . Well some thing doesn't seem right with your motor mate.
 

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Bumping this thread as I have exactly the same symptoms as original poster, the car going into limp mode when driven over @3k revs in 3rd with no engine warning light and resets when engine restarted. ECU says nowt, I have changed the MAF for a brand new unit and the problem persists, a full service also carried out and still the same problem.

Has anybody had the same, apparently common, problem and sorted it?

Does a failing N75 valve show up when fault codes are read?

Thanks in advance for any help or suggestions........
 

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Bumping this thread as I have exactly the same symptoms as original poster, the car going into limp mode when driven over @3k revs in 3rd with no engine warning light and resets when engine restarted. ECU says nowt, I have changed the MAF for a brand new unit and the problem persists, a full service also carried out and still the same problem.

Has anybody had the same, apparently common, problem and sorted it?

Does a failing N75 valve show up when fault codes are read?

Thanks in advance for any help or suggestions........
It will be the vains on the turbo sticking and causing the profile of them not to change and over-boost at lower rev's - solution: new turbo. This is really common on all PD engines.
 

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I've noticed on a few threads (and on my car) that limp mode occurs when going up hill ...

though mine is not going into limp mode, it does lose boost when on an incline.

Is there something that moves or is dependant on being level? There are no giroscopes are ther?!! it doesn't seem to do it with acceleration (G force simulating a climb) but when the car is actually on an incline... and is it limited to PD's?
 

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I've noticed on a few threads (and on my car) that limp mode occurs when going up hill ...

though mine is not going into limp mode, it does lose boost when on an incline.

Is there something that moves or is dependant on being level? There are no giroscopes are ther?!! it doesn't seem to do it with acceleration (G force simulating a climb) but when the car is actually on an incline... and is it limited to PD's?
The engine is under more load when climbing and requires higher boost.
 

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? not sure on that one... if floored from standing, when the engine will be under even more load than cruising at 70, the engines dont go into limp ...
 

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It wont just be limited to PD's, all the tdi's except the 90bhp model (AGR) engine come with the VNT series of turbochargers like the PD's do. Obviously the models are different for the different power ratings but still the same problem occurs.

Having said that, I had this problem on my old 90bhp motor and never really did get to the bottom of it. I tried fitting a boostvalve to limit the boost pressure and this worked for a while but it seems to have come back with the new owner.
 
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