I've got a problem with my b7 2.0tfsi randomly dropping revs then suddenly picking back up causing a jerk. Doesn't seem to be getting progressively worse and it happens really quite randomly, it doesn't show any check engine lights etc. I've changed the coils, sparks and turbo diverter valve thinking these could be the problem. I then read up about fuel cuts and replaced my fuel pump cam follower although this seemed to show no signs of hard wear, engine also makes a slight chatter noise around the top of the engine when it gets to temp. Ran a diagnostic several times and find the same codes. Only thing i could think about replacing now is the PCV with a REVO revamp however I'd like to check with any guys out there reading this before I fork out more money?
2.0tfsi power cut/jerk
- Thread starter mechmatthews
- Start date
Have you tried logging measuring blocks real pressure (230 and 231).
Could be a blockage in fuel filter?
Could be a blockage in fuel filter?
That's a strong idea, I'll have to try figure out how to log the fuel pressure as I'm a novice to vcds but ill try that, cheers!
Its not too hard once you get used to it
.
Go to Select Control Module>Engine>Measuring Blocks button (near left bottom). Then type 230 in one of those boxes and hit go.
In fact, here's a better description and if you follow these then that will help you identify if you are boosting etc within spec, which cylinders are misfiring etc http://www.goapr.co.uk/support/datalogging.php
I'm not expert, but happy to help and share my graphs of equivalent runs so you have some reference.
. Go to Select Control Module>Engine>Measuring Blocks button (near left bottom). Then type 230 in one of those boxes and hit go.
In fact, here's a better description and if you follow these then that will help you identify if you are boosting etc within spec, which cylinders are misfiring etc http://www.goapr.co.uk/support/datalogging.php
I'm not expert, but happy to help and share my graphs of equivalent runs so you have some reference.
Molnboman
Registered User
Glad you are getting help Mechmathews and welcome to the Forum Matey!
Good Luck and keep us posted in how you get on.
BR
A
Good Luck and keep us posted in how you get on.
BR
A
Have you changed the pcv recently?
I would be tempted to try that first as its a relatively cheap part. £30ish
I would be tempted to try that first as its a relatively cheap part. £30ish
Before you change the pcv, you can check if the valve has gone relatively easily, although it won't tell you if it is about to fail. I'll dig out a picture to help you in a bit
Molnboman
Registered User
I agree....the PCV is cheap replacement and diy.....a lot cheaper fix than most.....and worth a pop. He has changed everything else!
BR
A
BR
A
Agree with you it's not an expensive part. But I always like to try and diagnose before changing (and then change it anyway, ha!)
Here's the link to info on how to test PCV - see third pic down and comments just below it, shows you the pipe to pull off and blow down.http://www.audizine.com/forum/showthread.php/449451-Ultimate-Catch-Can-Reference
Here's the link to info on how to test PCV - see third pic down and comments just below it, shows you the pipe to pull off and blow down.http://www.audizine.com/forum/showthread.php/449451-Ultimate-Catch-Can-Reference
Molnboman
Registered User
One positive you can take out of all your replacing of all those parts.....your cam follower looks in great nick Mate which mains the upstairs department has plenty of life left in it. Was thinking summit, was the jerking cutting out happening before you changed the cam follower? If it wasn't perhaps you have bolted the HPFP back together incorrectly....just a thought.
Cheers
A
Hello all, thanks for all the replies, for the money a replacement PCV looks worth doing.
I also managed to log a run to work, recording my requested and actual fuel pressure which you can see in the picture. You will see a random spike which is well over 110psi, this is happened around the time i felt a jerk so i am practically sure that this result has something to do with my problem. This surely means my pump is working fine but got me wondering if the fuel rail regulator is having problems or if one of my injectors is failing?
I also managed to log a run to work, recording my requested and actual fuel pressure which you can see in the picture. You will see a random spike which is well over 110psi, this is happened around the time i felt a jerk so i am practically sure that this result has something to do with my problem. This surely means my pump is working fine but got me wondering if the fuel rail regulator is having problems or if one of my injectors is failing?
Attachments
The jerk could be hesitation, ora patial fuel lean off, did you inspect the camshaft when you replaced the follower?
Could be a sign of wear on the cam lobe that drives the hpfp.
It's quite common in these but usually a worn cam follower is the result, but doesn't totally eliminate it. Only the revised camshaft found in the bwa doesn't suffer from the same wear issue.
Could be a sign of wear on the cam lobe that drives the hpfp.
It's quite common in these but usually a worn cam follower is the result, but doesn't totally eliminate it. Only the revised camshaft found in the bwa doesn't suffer from the same wear issue.
I did check my cam upon changing the follower, I even took out my sparks and slowly turned over the engine to check a full rotation and its surface finished seemed completely fine. Would a fuel lean off cause my fuel rail pressure to spike to nearly 135psi like that? cheers for the interest
I could re-log a drive with the fuel pressures and revs tonight, ill try this and post it up.
Did you log any other blocks at the same time - you might have the rpm off that? I think ideally ideally try a few WOT runs (I have a place near me with 2 roundabouts about 1km apart in a 60mph zone - perfect for this!), in fact might make sense to log block 2 (MAF), 115 (Boost) and 230 (Rail) all on the same one a few times. Have you also logged misfires on cylinders 1-4? If not might be worth also doing a couple of runs logging that and Lambda (block 31 I think that is). I'm fairly new to this all, so I more or less get the gist of the above bits.
I haven't figured out what Cylinder Ignition Angle Delay, Throttle plat angles, ignition timing etc tell me although I know the APR link suggests to log them!
Big Al
Registered User
I think I know exactly what is causing this. Fueling errors cause softer cuts than you're probably experiencing. A harse, sudden, irregular cut is sensor error. Change your crankshaft impulse sensor. It's underneath the oil cooler / above the oil filter into the block. I had the same on my old car for 7 months, no VCDS errors at all. Audi Coventry thought it was the fuel sender, plus loads of other fuel related things (costing me a small fortune ££££). It wasn't, I fixed it myself for just over £100! I think the sudden engine jerk causes fuel pressure spikes too; once the impulse sensor is replaced, your car will probably run sweetly.....
Big Al
Registered User
Well others have have the crank impulse sensor (also known as Engine Speed Sensor G28) errors in the log -
http://forums.vwvortex.com/showthre...ne-Speed-Sensor-(-impulse-sender-)-DIY-w-pics
But my car showed no errors at all, even whilst monitoring with laptop whilst driving and it jerking sporadically.
Here's the Parts Base ETKA parts page -
http://www.partsbase.org/audi/audi-...nit-lambda-probe-knock-sensor-impulse-sender/
Part number listed is 06A906433L but you should check the latest part number with Audi or TPS. I sold my car so don't have the service history to see the Audi invoice.
Good luck with a fix! Alistair
http://forums.vwvortex.com/showthre...ne-Speed-Sensor-(-impulse-sender-)-DIY-w-pics
But my car showed no errors at all, even whilst monitoring with laptop whilst driving and it jerking sporadically.
Here's the Parts Base ETKA parts page -
http://www.partsbase.org/audi/audi-...nit-lambda-probe-knock-sensor-impulse-sender/
Part number listed is 06A906433L but you should check the latest part number with Audi or TPS. I sold my car so don't have the service history to see the Audi invoice.
Good luck with a fix! Alistair
Big Al
Registered User
Effectively yes. If you google crank impulse sensors for other makes of cars, you'll find plenty of threads describing the same driveability problems.
