car would not go over 40mph
Driving home the other day the car would not go faster than bout 40mph whatever gear I selected with foot hard to floor. There were not any warning lights on the dash. i only had a couple of miles to go and got home safely. The car was normal up to 40mph but would then not accelerate any more.
Tried again next morning (did not try again that day as I was returning from Mum's funeral and not in the right frame of mind), and it worked perfectly and has been OK the last couple of days.
Someone suggested that the car had gone into a 'get you home mode' but there were not any warnings. Any ideas please, and is this a sign that I should get something checked by garage?
Thanks
Re: car would not go over 40mph
You need to scan the car with VCDS. "limp mode" can be caused by turbo over-boost, failing N75 valve, loose clips on the pipes etc.
Re: car would not go over 40mph
Quote:
Originally Posted by
paynes1
Driving home the other day the car would not go faster than bout 40mph whatever gear I selected with foot hard to floor. There were not any warning lights on the dash. i only had a couple of miles to go and got home safely. The car was normal up to 40mph but would then not accelerate any more.
Tried again next morning (did not try again that day as I was returning from Mum's funeral and not in the right frame of mind), and it worked perfectly and has been OK the last couple of days.
Someone suggested that the car had gone into a 'get you home mode' but there were not any warnings. Any ideas please, and is this a sign that I should get something checked by garage?
Thanks
If it didn't light the dash up it's not going to be overboost,
I suspect a few things,
1 - Carpet mat was fouling the pedal and restricting it
2 - You have a vacuum air hose come loose or has a very small hole in it and this will cut the turbo out
3 - MAF is playing up although this may also have put lights on the dash
If you can get a reader on the OBDP you need to do it ASAP before the ECU clears any codes, not that I think there will be one as you had no dash warnings,
As it's now not doing it I'd say the carpet is favorite and you'd be surprised how many people do this and get caught out by it.
Re: car would not go over 40mph
Quote:
Originally Posted by
DSG4ME
If it didn't light the dash up it's not going to be overboost, .............
Overboost doesn't necessarily put any lights up on the dash.
Overboost typically has the following symptoms:
- Worse when hot, seldom initially from cold but getting worse over time (if turbo related rather than being N75 valve)
- When it happens, stopping, turning off the ignition and re-starting will put things back to normal for a while. The OP should try this.
- Sometimes, when climbing a long hill in high gear, the problem will kick in and power will seem to fade away. The harder you press the pedal, the more power fades. The trick is to accept what you have, feather the throttle as much as possible and hope that the bus you just overtook doesn't get too unhappy when you are slowing him down. Dropping to a lower gear doesn't help much.
- Completely intermilltent - can happen five times in a day then the car car drive fine for a week. This rules out several causes, including leaky vacuum pipes.
The OP doesn't say whether the car is manual or auto, but the symptoms can be even more frustrating on an auto because the engine ECU/gearbox mechatronic combination conspire together to try and achieve what the driver is requesting with his right foot, but at the same time keep the car in limp mode to avoid blowing the engine up. What you expereince can then be very misleading. Been there, done that!
But as you quite rightly say, a code scan is the first start.
I can't see it being the carpet, because the Passat has an organ pedal throttle that is more difficult to wedge the carpet under and in any case, the symptoms would be ameliorated by changing to a lower gear.
MAF often doesn't put lights up on the dash either and also sometimes doesn't throw up any codes. It is frequently suggested as the first choice for this sort of thing and is easy to check and eliminate just by disconnecting it for a while, but sadly it's usually not the cause.
One other cause that a code scan may point to is a failed MAP sensor. It is cheap to swap for about £80, and easy to do providing its location is accessible. Sometimes, the front bumper has to come off to get to it. I've no idea where it is on the OP's car.
But code scan first.
p.s. My first visit to the forum, 6 years ago was with the very same symptoms and after 3 months of various garage attempts to fix it. I feel your pain. :alcoholic
Re: car would not go over 40mph
Quote:
Originally Posted by
Teflon
Overboost doesn't necessarily put any lights up on the dash.
Overboost typically has the following symptoms:
- Worse when hot, seldom initially from cold but getting worse over time (if turbo related rather than being N75 valve)
- When it happens, stopping, turning off the ignition and re-starting will put things back to normal for a while. The OP should try this.
- Sometimes, when climbing a long hill in high gear, the problem will kick in and power will seem to fade away. The harder you press the pedal, the more power fades. The trick is to accept what you have, feather the throttle as much as possible and hope that the bus you just overtook doesn't get too unhappy when you are slowing him down. Dropping to a lower gear doesn't help much.
- Completely intermilltent - can happen five times in a day then the car car drive fine for a week. This rules out several causes, including leaky vacuum pipes.
The OP doesn't say whether the car is manual or auto, but the symptoms can be even more frustrating on an auto because the engine ECU/gearbox mechatronic combination conspire together to try and achieve what the driver is requesting with his right foot, but at the same time keep the car in limp mode to avoid blowing the engine up. What you expereince can then be very misleading. Been there, done that!
But as you quite rightly say, a code scan is the first start.
I can't see it being the carpet, because the Passat has an organ pedal throttle that is more difficult to wedge the carpet under and in any case, the symptoms would be ameliorated by changing to a lower gear.
MAF often doesn't put lights up on the dash either and also sometimes doesn't throw up any codes. It is frequently suggested as the first choice for this sort of thing and is easy to check and eliminate just by disconnecting it for a while, but sadly it's usually not the cause.
One other cause that a code scan may point to is a failed MAP sensor. It is cheap to swap for about £80, and easy to do providing its location is accessible. Sometimes, the front bumper has to come off to get to it. I've no idea where it is on the OP's car.
But code scan first.
p.s. My first visit to the forum, 6 years ago was with the very same symptoms and after 3 months of various garage attempts to fix it. I feel your pain. :alcoholic
Point taken with the carpet but you never can ignore it as you just don't know
Overboost puts the car into limp mode ime so you would get engine garage message and the lit engine light on the dash
Being as it's been days without no update I would think he's either sorted it or slung it in the garage, an update would be nice but that is the way of the internet these days, fix my sh/t and walk away until I need you again, it caused a bit of a ruck in another thread recently where the helping poster blew a gasket at what looked like just another ignorant user on first glance.
Re: car would not go over 40mph
Hi all,
Many thanks for taking the time to answer, I was trying all of the suggestions I could before getting back to you (DSG4ME!).
I checked the carpet, and that did not seem to be the issue. The car has been fine the last couple of days, but I thought I'd play safe and get it checked on the computer whilst the service was being done (serviced early so that car still within after market warranty).
The fault showed up as - P1592 ALTITUDE SENSOR SIGNAL/CHARGE AIR PRESSURE SENSOR FAULT. Car to be booked in next week so that they can investigate further.....They had not seen this code before.
I'll keep you up to date.
Also, the rear passenger window switch on the driver's door console is not working although it is OK on the actual door. Being fixed under warranty when the car is back with them.
Re: car would not go over 40mph
With that code it's probably a bad earth
Re: car would not go over 40mph
Quote:
Originally Posted by
DSG4ME
Overboost puts the car into limp mode ime so you would get engine garage message and the lit engine light on the dash
No, sorry, I don't want to labour the point but the statement is WRONG.
I had 3 months of limp mode caused by overboost with no lights on the dash. Never. We did get codes, hence the reason for a garage changing first the MAP sensor then the exhaust recirc sensor (or valve?) then the fuel filter and even the battery before I arrived at the actual cause via the forum. I've seen the same thing since. Again, with no lights.
Granted, there may be circumstances when the combination of factors will pop up a warning light, but it is bad advice to suggest that it is as inevitable as death and taxes.
At least VW give you a code to work from. I'm currently struggling with my son-in-law's Volvo, which has limp mode and horrible black smoke but after two weeks and probably 100+ miles of taking it home every evening, a Volvo main dealer can't bottom it because there are no codes, therefore Volvo UK Technical are saying there can't be a problem and we must be imagining it. The Volvo forum is no use, there might as well be tumbleweed blowing around on screen when I asked for advice.
Re: car would not go over 40mph
Quote:
Originally Posted by
Teflon
No, sorry, I don't want to labour the point but the statement is WRONG.
I had 3 months of limp mode caused by overboost with no lights on the dash. Never. We did get codes, hence the reason for a garage changing first the MAP sensor then the exhaust recirc sensor (or valve?) then the fuel filter and even the battery before I arrived at the actual cause via the forum. I've seen the same thing since. Again, with no lights.
Granted, there may be circumstances when the combination of factors will pop up a warning light, but it is bad advice to suggest that it is as inevitable as death and taxes.
At least VW give you a code to work from. I'm currently struggling with my son-in-law's Volvo, which has limp mode and horrible black smoke but after two weeks and probably 100+ miles of taking it home every evening, a Volvo main dealer can't bottom it because there are no codes, therefore Volvo UK Technical are saying there can't be a problem and we must be imagining it. The Volvo forum is no use, there might as well be tumbleweed blowing around on screen when I asked for advice.
Overboost on a Passat B6 goes like this..........ping........sudden deceleration.......flashing coil light and engine fault message on dashboard, I know cos mine does it anytime I beans it onto the motorway, it's only ok if I build speed and then it doesn't tend to do it.
Re: car would not go over 40mph
Quote:
Originally Posted by
DSG4ME
Overboost on MY Passat B6 WENT like this...UNDER QUITE SPECIFIC CIRCUMSTANCES.......ping........sudden deceleration.......flashing coil light and engine fault message on dashboard, I know cos mine does it anytime I beans it onto the motorway, it's only ok if I build speed and then it doesn't tend to do it.PLUS, I HAVE NOT BOTTOMED IT OR UNDERSTOOD THE CAUSE AND PLEASE UNDERSTAND THAT MINE IS ONE CAR, NOT REPRESENTATIVE OF THE ENTIRE COHORT
There, fixed it for you.
