VR6 woes

[alip_corrado 0]

Hi all,

 

My VR6 isn't running right and hasn't been for a while now.

 

The issue started about two months ago now. It feels like there is a cylinder missing; symptoms are less power across the entire rev range, the car vibrating more than usual at idle, lumpy running and juddering at low engine speeds. The juddering, for example, occurs when in 5th whilst applying any amount of throttle at any speed under 40mph. Before there would be no trouble applying the throttle at speeds as low as 30mph (as any VR6 owner will be likely to confirm).

 

As soon as this behaviour began, I plugged the car into Vag-com. The camshaft position sensor was reported as faulty. I replaced the camshaft position sensor and cleared the fault. The behaviour did not change and the engine still ran lumpy. Since then that fault has not been reported again on Vag-com.

 

As the engine was still running lumpy and no faults were present when using Vag-com my thoughts turned to coilpack, spark plugs and ignition leads. I have replaced the coilpack with a second hand unit to no avail, as well as a new set spark plugs. I have also borrowed a single ignition lead from a friend with a Golf VR6. Using the single lead I swapped out each ignition lead in turn, starting the engine after each lead was swapped. Swapping each lead made no difference either.

 

After trying the above I tried replacing the MAF for a second hand unit but still no joy.

 

Someone has recommended replacing all 6 leads at once, rather than swapping them out 1 by 1. Would anybody suggest trying this?

 

Is there anything else anyone can think of that might be causing this fault?

 

Many thanks in advance for any response.

 

Ali.

[Dox 23]

Can you borrow a crank sensor? For the cam sensor fault code it compares crank and cam timing, if either is out it throws a cam sensor fault.

 

With the engine running in the dark, use a garden hand sprayer to mist water over the plug leads and watch for sparks, you can also measure the leads resistance with a multimeter, the longer the lead the higher the resistance. Most plug lead problems are caused by owners pulling on the leads themselves rather than using the removal tool clipped to the bonnet stay

[floppyman 0]

Have you put your usual fuel in there or you used some different?... I would say injector. Remove all spark plugs and have some one crank the engine for you, while you check if theres fuel spray coming out of the cylinders. Careful though

I had a problem like that after filling up with esso one day. Turned out the injector number 1 was over fuelling.

Is yours smoking at all?

Edited November 12, 2011 by floppyman

[eugopnosaj 0]

My car also judders, practically all the time when i come off of acceleration, the whole car seems to jolt. I havent had any fault codes reported. It does run a bit lumpy but isnt down on power i dont think

[floppyman 0]

My car also judders, practically all the time when i come off of acceleration, the whole car seems to jolt. I havent had any fault codes reported. It does run a bit lumpy but isnt down on power i dont think

 

I would check the pot at the throttle, might need adjusting. Vr6 have this pot on the throttle so that when you let go of the throttle it brings the flap slowly to close.

[eugopnosaj 0]

 

Number 5? IIRC i think it was a bit stiff/sticking, can they be taken off and cleaned, or what is the best way of adjusting it?

[floppyman 0]

Im not shure if it can be cleaned... Maybe take it out and "exercise" it a little and see.

There is a method to adjust it wich envolves a 4mm drill bit, but I have the bentley manual at home ill take a pic when I get there

[eugopnosaj 0]

Cool, thanks for your help :)

[RW1 0]

All covered here....

http://the-corrado.net/showthread.php?58046-Strange-stalling-problem&p=742922&highlight=throttle+damper#post742922

 

VR6's are sensitive to fuel pressure in their standard form. When was the last time the fuel filter was changed located on the underbody near the rear right wheel?

 

.

Edited November 12, 2011 by RW1

[alip_corrado 0]

Can you borrow a crank sensor? For the cam sensor fault code it compares crank and cam timing, if either is out it throws a cam sensor fault.

 

With the engine running in the dark, use a garden hand sprayer to mist water over the plug leads and watch for sparks, you can also measure the leads resistance with a multimeter, the longer the lead the higher the resistance. Most plug lead problems are caused by owners pulling on the leads themselves rather than using the removal tool clipped to the bonnet stay

 

Hi Dox, thanks for the reply.

 

The camshaft position sensor fault has disappeared from vag-com since replacing it. Do you think what I have could still be related to that?

 

I will try as you say a use spray gun to make a mist and look for sparks. No sparks = fault with that particular plug/lead?

I shall also check the resistances of each lead, I'm guessing the leads' resistance should be next to 0? Anything around or greater than 0.5 ohms would indicate something wrong I'm guessing. I do have the tool for removing leads and have always use it so I would hope that wouldn't be the cause of any faults with a lead if there is one.

 

Have you put your usual fuel in there or you used some different?... I would say injector. Remove all spark plugs and have some one crank the engine for you, while you check if theres fuel spray coming out of the cylinders. Careful though

I had a problem like that after filling up with esso one day. Turned out the injector number 1 was over fuelling.

Is yours smoking at all?

 

Hi floppyman, thank you for you're response.

 

I haven't put any fuel out of the ordinary into the car. I will try what you recommend and crack the engine to check that fuel is being injected. There is a little bit of black smoke on a cold start up. Apparantly when accelerating hard there has been a bit of black smoke from the exhaust. My mrs noticed this once a while ago whilst following in her car. This was before the running issue and I've not got someone to check since the running issue started again.

 

All covered here....

http://the-corrado.net/showthread.php?58046-Strange-stalling-problem&p=742922&highlight=throttle+damper#post742922

 

VR6's are sensitive to fuel pressure in their standard form. When was the last time the fuel filter was changed located on the underbody near the rear right wheel?

 

.

 

RW1, thanks for the link to the other thread, I will try the throttle checks aswell. My VR6 is in standard form, with the exception of a remap which a previous owner had done. I have changed the fuel filter quite recently, probably around 5 to 10 thousand miles ago when I had to replace a leaking fuel pipe. If fuel pressure could be the cause, is there a chance that it might be a dodgy pressure regulator?

 

 

Thanks again to all that replied.

[Dox 23]

No sparks when misted with water is good with the engine running and all plugs connected, you're checking the leads aren't breaking down and one lead cross-firing to another or direct to earth - you're replicating what happens on a damp morning start.

 

I'd expect the shortest of leads to be around 20K ohms, the longest 30-35K ohms and the others to step up between dependant upon length.