VR6 misfire (distributor engine) FIXED FINALLY

[Neil VR6 0]

Hi all

 

Just as one problem's fixed another comes along :brickwall:

 

The car's got a misfire and sounds like it's only firing on 5 cylinders.

 

I was going to start out by replacing the plugs and leads but I've just looked through the car's history file. In June 2006 at about 99K miles it had new leads, plugs, rotor arm and dizzy cap. Then in April 2007 it had another new rotor arm, dizzy cap and plugs at around 118K miles. All parts were from GSF. it's done 128K now.

 

Does my car have an appetite for ignition parts or are the GSF parts poor quality? Alternatively what else could it be? :shrug:

 

I've also noticed that one of the pins on the MAF has been all but dissolved as moisture has got into the plug assembly - it's all green and slimy (presume it's copper). Could the two things be linked or have I just got two separate problems? :(

 

Cheers

[Neil VR6 0]

Anyone got any ideas?

[was8v 0]

GSF leads are rubbish - get OE Leads from http://www.vwspares.co.uk/corrado_electrical.php

 

 

First off pull your plugs to see which cylinder is missing, the duff one will be obvious.

 

You may have a plug (1 or 6) fouled up with oil (common due to VR bore wear at this mileage or stem seals) either wet with oil or manky and covered in black lump. If this is the case, put a new plug in and try a thicker oil. They can go for many more miles before further problems.

 

A plug may be wet with petrol (sniff it) in which case swap the plug lead to this with another and see if the missfire follows the plug lead. If so get new leads.

 

If the missfire doesn't follow, you may have a faulty (stuck open) injector. I had this issue on a 110k 1992 dizzy VR6, an injector was stuck open flooding the cylinder with petrol dousing any spark - swapping the injecter for a known good one fixed the issue. I have some for sale viewtopic.php?f=13&t=76892

 

Won't hurt to get a compression tester and do a quick compression test to see the health of the engine.

 

Er get that MAF pin cleaned up, the car should stall if you pull the MAF plug whilst its running (not recommended to do this) If it doesn't then the idle will need adjusting and the car will prob have trouble at emmissions test time.

[Neil VR6 0]

Thanks very much :)

 

Do you need a special tool for the plug removal on a VR?

[was8v 0]

Thanks very much :)

 

Do you need a special tool for the plug removal on a VR?

 

 

You need the plug lead (maybe a plastic one clipped to your bonnet stay or with the spare wheel?) to pull the leads off without damaging them.

 

No special tool, just the right size spark plug socket and an extension to reach them.

[Neil VR6 0]

I found my lead remover in the spare wheel but the poxt GSF leads must have a different design which doesn't work with the VAG tool. Just going to replace them as a matter of course now as I nicked one with some pliers.

[was8v 0]

If you need some good injectors to try, I'm nowing giving my spares away for free if you cover postage, see link in sig.

[Neil VR6 0]

I actually replied to that thread too :) I'm happy to more than cover postage if it turns out that one of the injectors is at fault

[Neil VR6 0]

It's definitely not the injector.

 

The MAF's been fixed - a neat bypass job to make the wiring good again. That fault's cleared now.

 

One of the plugs was completely soaked so all of them were replaced and the misfire's gone.

 

However, it won't idle from cold any more at all and hot idle is pretty ropey. It also has no power at all - floor it in second and the noise is there but it struggles to produce any power and feels very ropey :shrug:

 

I'm really losing my patience with this - the G60 was so reliable compared to the VR :cry:

[was8v 0]

One of the plugs was completely soaked so all of them were replaced and the misfire's gone.

 

 

Soaked with what? Oil or petrol?

 

Does the same one get soaked even if you move them round and swap leads etc?

 

If its petrol on the plug then you need to whip it out quick before the petrol evaporates to see if its still there.

 

Why do you say defo not an injector?

[Neil VR6 0]

Should have said - the plug was soaked with petrol.

[Kevin Bacon 5]

1 or 6?

 

Unlikely to be one injector, more likely to be bore wear and it's oil fouled. You're smelling petrol on the plug because that cylinder is misfiring.

[Neil VR6 0]

Number 5 was the culprit so that suggested that it wasn't bore wear - just a faulty plug. In any case the midfire's gone now. Now it won't idle and won't pull. (the car, not girls)

[Kevin Bacon 5]

Not necessarily, I've seen cylinder 5 go the same way as 1 and 6!

So it was a dodgy plug after all that then?

That's a (cheap) relief!!

[Neil VR6 0]

That was fixed cheaply but now it's now got about 30hp and won't idle.

[Toad 0]

Think it's time to VAG COM.

[was8v 0]

Think it's time to VAG COM.

 

 

Yeah maybe cam sensor or MAF is duff, VAGCOM will help, in fact it should be the very first thing to do!

[Neil VR6 0]

After much investigation it turns out my distributor’s shot. It took so long to diagnose because the symptoms (no mid range grunt) are unusual. It’s obsolete from VAG now but I’m getting my old one rebuilt here for £100 +vat with a 3yr warranty:

 

http://www.ignitioncarparts.co.uk/index.aspx

[was8v 0]

After much investigation it turns out my distributor’s shot. It took so long to diagnose because the symptoms (no mid range grunt) are unusual. It’s obsolete from VAG now but I’m getting my old one rebuilt here for £100 +vat with a 3yr warranty:

 

http://www.ignitioncarparts.co.uk/index.aspx

 

 

 

How did you diagnose that!

 

Is it the hall sensor in the dizzy thats gone? I hear they cause lots of funny problems with G60s

[Neil VR6 0]

It was at a local VW specialist (AllDub tuning, forum member 'corradorun' works there and had been working on it) and they spent an awful long time taking things apart and running diagnostic checks. I sent the dizzy back yesterday and it'll be back tomorrow. If this doesn't fix it I'm going to push the damn thing off Beachy Head!

 

Basically it would rev whilst stationary but when it was under load the revs would only rise very slowly which was diagnosed as a timing issue. Further investigation into the dizzy revealed the 3 pin multi plug hanging out and presumably the hall sensor playing up. It must be the original unit (it's a Bosch) which means it's been working for 128K miles which I guess isn't too bad! The car also burnt through a rotor arm and cap in 2006 and 2007

[Neil VR6 0]

The lack of power has been solved by the recon'd dizzy - great.

 

It still won't idle from cold though. Apparently it's not the ISV or the choke sensor. Fuel pressure is fine too. However, if you pinch the fuel return (and consequently raise FP) when it's cold it idles fine. All plugs look fine. Could this be symptomatic of a blocked injector or somethng else? It also revs and pulls fine right to the redline so that suggests the fuel pump is OK

[TomB 0]

Glad to hear the new dizzy solved the problem (I'm getting a new one from Bosch tomorrow...) but I'm at a loss to help you with the lack of idling from cold as mine doesn't have that problem (yet :D ).

 

Good luck,

Tom

[Neil VR6 0]

Well I got the car back yesterday and it's not better, at all. It drives like a complete dog and still has an intermittant misfire. It's had a recon dizzy, new plugs, new mani to mani gasket, new FPR and a rewired MAF. What's more the wasters at that place that recon'd the dizzy left a lump of magnetic metal inside the casing and didn't bother putting a grub screw on the new rotor arm. :brickwall:

 

Total cost so far = ca £500. Progress = 0

 

Chances of selling car and buying another Pug 205 diesel = 4:1

[TomB 0]

You know how I joked about not having that misfire (yet) at idle.... well guess what you get for tempting fate.

I've spent the same amount of money, and had the same shopping list as you Neil, and still have the same problems.... I'm going back to the garage on Monday so if they find it before you do, I'll be sure to let you know.

 

Cheers,

Tom

[Neil VR6 0]

I feel for you I really do. Mine's getting trailered off this week to JMR - where I should have taken it all along.