Juddering at low revs

[Bern 0]

My car has started to judder between 1000-2000rpm and feels like its lost a bit of power, i did add BMC DIA air filter a couple of days ago and wondering if i had damaged the MAF? How can you tell if the MAF is working fine?

Also not sure if it could be the coilpack or HT leads, i've got a new set of spark plugs ready to be fitted aswell.

[Smuggler 0]

Sounds like ignition to me, try the plugs first, if that doesn't help then ts on to leads and coil pack, or dizzy/cap.

[scott-mk3 0]

My mate had this problem with this VR.it was fine when high reving and didnt seem like there was a problem

End of the day it was the fuel pressure regulator.

£65 from euro car parts i think.Try maybe fuel filter aswell though as his was really clogged.

[ip 0]

This is the classic VR problem. Mine did it (exactly as you describe) and there are loads of forum threads the world over covering it too.

Top six list of stuff to try:

1. Plugs (also lets you check how engine is running in general: lean/rich)

2. HT Leads. Not as expensive as you think. I got a set off ebay for £27 and they work well and look great.

3. Coil Pack/dizzy (again, lots of scope for cheaper used parts on ebay etc here)

4. MAF (I have a spare I could sell you that works fine, though I don't expect you'll need it)

5. Fuel pump/filter/pressure regulator

6. Lambda sensor

I replaced all the above as well as temp sensors before finding it was the HT Leads. Felt like a chump as they are one of the most widely reportrd failures on the VR. I had tried the old trick of spraying water onto the leads at nuight and checking for sparks but that showed up nothing (maybe because of the very deep wells into which the HT leads have to be run?). Either way, they remain my top tip for any lumpy VR

Meanwhile, MAFs don't fail as often as people think. There's a guy on VW audio forum who's pretty knowledgable (works on VEWs for a living) and he reckons MAFs fail once in a blue moon.

Hope that helps.

ip

[Bern 0]

Sorted it now, i replaced the spark plugs today and it isn't juddering anymore at all. The old plugs were well and truly knackered by the looks of them. Thanks for the replies though everyone.

[Bern 0]

Ok well it stopped juddering after i replaced the spark plugs now two days after it has started again, anyone know what it could be?

[Smuggler 0]

Leads or coil pack, sounds like the plugs had taken most of the strain off whats causing the problem, but has now come back which indicates ignition fault in my opinion.

[ip 0]

refer to the list I alreday gave you. This is what you have to work through in the correct order. Smugler is right. New plug spark more easily so take strain off other weak componenet but, as you noticed, only temporarily:

1. Plugs (also lets you check how engine is running in general: lean/rich)

2. HT Leads. Not as expensive as you think. I got a set off ebay for £27 and they work well and look great.

3. Coil Pack/dizzy (again, lots of scope for cheaper used parts on ebay etc here)

4. MAF (I have a spare I could sell you that works fine, though I don't expect you'll need it)

5. Fuel pump/filter/pressure regulator

6. Lambda sensor

[Bern 0]

How do i tell if the HT leads/Coil Pack or Dizzy are knackered? Is there ways to test them?

[ip 0]

Firstly, do yo uhave a coilpack or dizzy? Both sit on end of cylinder head (gearbox end of engine) and have six HT leads going to the spartk plugs. Dizzy is circular. Coild Pack is rectangular. Look on web, loads of pictures.

In answer to your question though. No, there is no reliable way to test the HT leads or dizzy/coil/coilpack. The dizzy can be evaluated by an experienced eye but the leads and coil cannot be tested in any manner that I have found (there is a technique described in the Bentley manual but sadly it does not work on 90% of coil failures). Extreme HT lead failures can sometimes be seen by spraying water onto the engine while it is running at night. You will see arcing between the leads and engine bolck. This is basically the spark taking a shorter route to earth through the lead rather than through the spark plug. Since VR6 leads tend to fail near the plug (and so deep down in the spark plug well) this test is not very succesful.

So, once again, please refer to my list:

1. Plugs (also lets you check how engine is running in general: lean/rich)

2. HT Leads. Not as expensive as you think. I got a set off ebay for £27 and they work well and look great.

3. Coil Pack/dizzy (again, lots of scope for cheaper used parts on ebay etc here)

4. MAF (I have a spare I could sell you that works fine, though I don't expect you'll need it)

5. Fuel pump/filter/pressure regulator

6. Lambda sensor

Work through these items one by one and you will find the issue. I have listed them in order of likelyhood and cost so this forms the cheapest route to solving your problem.