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MikeT
MikeT, VW Technician
Category: VW
Satisfied Customers: 274
Experience:  VW dealer registered and certified. 10+years VW/Audi experience. Avid VW enthusiast.
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My car jerks when accelerating,when the engine is up to normal running temp

Customer Question

I have 2001 vw passat estate 130 tdi.The car has 150 000 miles on the clock,and has full service history.It has develop a rather annoying fault which only seems to occur when the engine is at normal running temp.If i accelerate the car jerks,I then have to lift off the accelerator and gently accelerate,the jerking is less but still there when I do this,but at least it will actually speed up.
I have had it seen to,but no faults are showing up on the diagnostics.The workshop even had it for a week and could not resolve the issue.

So I did some research and was told that the harness in the head causes this issue.Replaced that,no difference,I then cleaned the egr valve out still no improvement.Next gave the maf a clean out,same result,also tried the temp sensor thats on the intake pipe from the inter-cooler.Non of this has helped.The temp sender unit was replaced too
I even tried injector cleaner.
I am quite baffled by this and suspect that it is a temp related electrical fault.
Submitted: 5 years ago.
Category: VW
Customer: replied 5 years ago.
Relist: I still need help.
Expert:  MikeT replied 5 years ago.
Jon,

TDI's will not usually activate faults for concerns like this. This sounds like a clogged EGR valve or EGR cooler. I would also say MAF, but that should throw a fault. Do you have a suitable scan tool?

How many miles on your TDI? Has the timing belt been replaced? I would like you to check injection pump timing.

With my experience I ALWAYS start diagnosis of rough or sputtering running with a new fuel filter and a can of diesel purge (diesel fuel additive). This will resolve lots of rough running concerns.


-Mike
Customer: replied 5 years ago.

I have changed fuel filter and used fuel additive twice.

As in my first post,the vehicle has done 155000 miles,has FULL service history,and has been looked at more than once for this fault,but they are unable to resolve the issue.

I have cleaned the EGR,Maf and Intake temp sender unit,to no avail.

Cambelt has been done at the required service invals,as per the full service history.

If it was the injector pump timimg,surely the fault would be there all the time

 

Any other ideas?

Expert:  MikeT replied 5 years ago.
The fault could not show for incorrect injection pump timing. Do you have a suitable scan tool (vag-Com) to check this? Have you also cleaned the EGR cooler and intake manifold, not just the valve? Are you running any alternative fuel?

-Mike
Customer: replied 5 years ago.

Hi Mike,

I had the car plugged in and driven for about an hour on the motorway,the car 'miss fired' alot during this time,but the vag tool did not show any faults.However the MAF reading was a bit low at full throttle.

So I replaced the MAF,but it has made no difference.

I did not clean the intake cooler and MAF manifold,will try this this weekend and see how I get on.

It is strange that it only happens when up to running temp.At cold the fault is not there.

Expert:  MikeT replied 5 years ago.
Yes this is normal. The plugged EGR cooler and injection pump will only act up when at operating temp.

-Mike
Customer: replied 5 years ago.

Hi, again,

I have flushed out the intercooler and cleaned all the pipe-work out.I also replaced a few vacuum pipes that looked a bit frayed.

The issue is still present.Even though the car has been serviced at the correct intervals,I will replace the fuel filter and air filter this coming weekend.

 

Is there anything else you could suggest looking at?Dual mass flywheel perhaps?I am grasping at straws at this stage as I am at my whits end.

 

thanks

Jon

Expert:  MikeT replied 5 years ago.
Dual mass flywheel will not cause this concern. Have you chceked the injection pump timing like I said with the Vag-Com?

-Mike
MikeT, VW Technician
Category: VW
Satisfied Customers: 274
Experience: VW dealer registered and certified. 10+years VW/Audi experience. Avid VW enthusiast.
MikeT and 5 other VW Specialists are ready to help you
Customer: replied 5 years ago.

Hi Mike,

Am getting the pump timing checked with Vag-com tomorrow,also have a bosch injection system specialist looking at it(Free of charge,fortunately).Will advise how I get on,thanks

jon

Customer: replied 5 years ago.

Hi MIke,

Car is sorted now.Replaced the fuel filter,and issue stopped immediately.The garage that serviced the car put some aftermarket one in,now has a genuine filter in.

The injector timing is spot on,however the turbo is overboosting very slightly,so will sort that this weekend.

thanks

jon

Expert:  MikeT replied 5 years ago.
Glad I could help. As stated in the first reply. Fuel filter is ALWAYS the first replaced part for poor running diesels. After market parts are JUNK...

Glad its running great.

Thank you for the accept

-Mike

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