VR6 - misfiring, rough running till warm..

[Jim 2]

My VR6 has suddenly started to misbehave a bit :( This morning when I set off to work I thought she felt like she was misfiring a bit and it was especially noticable when the engine was under load and more so between 600-1700RPM. As I drove in, I found the car got better and was normal by the time I got there. Symptoms were lumpy / jerkiness, and sounded like very occasional popping from the engine pay.

 

This evening went to drive her home again and the same.. if not worse. Could smell fuel at some points too. It's weird as this hasn't developed over time - it's just suddenly started to happen.

 

I've done a search (being utterly clueless about the VR6) and suggestions seem to be leads, coilpack and plugs. The leads I'm fairly sure are very new VW but I have no history for the car beyond a service book so have no idea what else has been changed. Search results seem to suggest coilpack is a likely candidate here..

 

I'm also wondering if it could be a bad batch of VMax - I only just filled it up yesterday....

 

Cheers.

[Kevin Bacon 5]

Coilpack I reckon, it's the only thing Neil didn't change!

 

Got 3 or 4 'in stock' if you can wait until next friday when I come up?

[dr_mat 0]

Same here. And I've seen two or three other posts about the same thing recently. It seems there's a serious humidity + cold blip that's toasted the coil packs out there. Open the bonnet and listen - you'll probably hear the HT arcing around the coil pack. Even at idle you'll probably find it runs a bit rough for a while.

[Mark_Storm 0]

Try spraying some water on the coilpack when its idling. You should see a bit of a lightshow (the spark shorting out on the engine block - not causing any damage) which will confirm that's the problem and show you where the crack is. I bought a 2-part epoxy resin (about £5) and sealed mine up and that was 3/4 years ago, not had a problem since. My bro had to do the same on his VR6 golf

[Jim 2]

Coilpack I reckon, it's the only thing Neil didn't change!

 

Got 3 or 4 'in stock' if you can wait until next friday when I come up?

 

Thankfully got the old valver so can ease off on the VR for a few days. That'd be excellent Kev and will pay whatever's the going rate - are they new, or known good second handers?

[Jim 2]

Try spraying some water on the coilpack when its idling. You should see a bit of a lightshow (the spark shorting out on the engine block - not causing any damage) which will confirm that's the problem and show you where the crack is. I bought a 2-part epoxy resin (about £5) and sealed mine up and that was 3/4 years ago, not had a problem since. My bro had to do the same on his VR6 golf

 

Yeah - know about the old epoxy trick. Good way to save a few quid but would just as happily replace the item rather than patch it up.

[easypops 8]

Thats exactly the same as mine........i replaced the coilpack with a second hand one and it did help for a wee while but started doing the same again.......did the mist thing and it showed arcing........now got a new one waiting to go on.........when its a bit warmer out in the garage :lol:

[Mark_Storm 0]

A good epoxy resin will be stronger than the plastic used to make the coilpacks and with one pack I managed to cover about 2/3rds of the coilpack. When I did mine I read a couple of people who bought new, and then covered it in the epoxy resin, but that seems a bit daft to me

[Jim 2]

Was terrible again this morning.. only really getting smooth once the engine oil got to about 80 centigrade. I think I might lay the VR up for a few days until I can get a coilpack sorted and revert to the valver!

[Kevin Bacon 5]

Coilpack I reckon, it's the only thing Neil didn't change!

 

Got 3 or 4 'in stock' if you can wait until next friday when I come up?

 

Thankfully got the old valver so can ease off on the VR for a few days. That'd be excellent Kev and will pay whatever's the going rate - are they new, or known good second handers?

 

They're all s/hand but barely used as I don't use VR6 coilpacks on my engine :D

 

I'll bring VAG-COM and a pile of the usual suspects parts too....

[easypops 8]

I don't use VR6 coilpacks on my engine

 

Tell us more........is this the saab one you have mentioned in the past?.........any more info on this? and whats needed to fit? it and is it better?.........thats all the question for now :lol:

[jamiehamy 0]

Hmmm.. I had the same issues you've described Jim, fixing itself at running temperature (well, 65degrees oil).

 

I replaced the blue temp sensor and it 'seemed' fixed, but reappeared once just after I tweaked the gas map. Never had it since though.

 

Def the same symptoms with spluttering, coughing and sometimes popping, but not on full throttle (which led my thoughts to the lambda loop kicking in too early, hence blue temp sensor. A new one was about £15 from VW.

 

Just a thought...

[easypops 8]

I replaced the blue temp sensor

 

Any chance of a part number?.........and where abouts it goes on the engine? :D

[jamiehamy 0]

I replaced the blue temp sensor

 

Any chance of a part number?.........and where abouts it goes on the engine? :D

 

Not got the part number to hand I'm afraid, but it's fairly easy to replace.

 

It's on the front of the engine as part of the thermostat housing. At the front right of the inlet manifold, go down and you should see a black cover. They are underneath that, a blue, yellow and black one.

 

The cover slides off ( can't remember if it's sideways or upwards). Take off the wiring connectors (squeeze the metal clips at the side) There is a clip holding the sensor in - a small screwdriver will prise it up and off. Then you just pull at the sensor and it'll come off. Make sure the rubber seal comes out too or you'll have issues fitting the new one.

 

The coolant will pour out sadly unless you have something handy to stop it like a thick rag. Press the new one in, slide the retaining clip down and reconnect the wiring. Shouldn't take long at all :) Bit tight space wise so might need to detached the radiator and push it forward slightly.

 

I fitted a VAG part as i've heard a lot of bad stories about Euro ones.

[Kevin Bacon 5]

I don't use VR6 coilpacks on my engine

 

Tell us more........is this the saab one you have mentioned in the past?.........any more info on this? and whats needed to fit? it and is it better?.........thats all the question for now :lol:

 

Aye, this one - http://www.bosch-motorsport.de/pdf/comp ... ls/3x2.pdf

 

It's from the GM 2.5 V6, as fitted to Vauxhalls and Saabs. Cavalier, Calibra, Omega, Vectra, Saab V6 of that vintage (1995 - 2000 IIRC) etc etc, so plenty of breakers to try.

 

If you're not particular about originality and aren't scared of simple mods, it can be quite a cost effective solution.

 

The main issue with the standard coilpack is VW will only sell you the whole unit at £200ish inc VAT, but it's usually always just the coils that blow. The coil amplifier attached to the ally cradle gets needlessly binned when replacing the pack.

 

The new cost of the Bosch coils is £120ish IIRC, so still a saving over a standard unit.

 

I'll post up details at some point.

 

As for 'better', I can't say. In the context of a standard engine probably not, but I have run some coil tests and saw a stronger spark from the Bosch pack!

[Tekara 0]

Another VR playing up here too Jim. Started a week ago, was fine when a set off for work, part way there it was down on power and very lumpy. Parked up at work and came to leave in the evening and all was good, again part way back the problem resurfaced. Ever since there is been lumpy and jerky from start - very strange exhaust note.

 

Just tried changing the plugs and leads and no difference, thought much the same as you as i only filled up with VMax the night before the problems started. Guess a coil pack is on the cards now :(

[Jim 2]

Will let you know what happens when I swap one with Kev next week. Just did a 100 mile run down to see 2cc here in Wiltshire today and it was fine once up to temperature.. but ropey until oil was about 86 centigrade!

[Tekara 0]

Have you had the plugs out Jim? Just took the fresh plugs out again after a quick drive and found 5 & 6 were wet and smelt of fuel - looks like i have a VR4 at the moment.

[dr_mat 0]

Well I swapped the coil pack on mine this weekend, same symptoms, and it ran just fine, totally back to normal. There's a hairline crack up the side of the old coil pack.

[Pat_McCrotch 0]

Not the blue temp sender is it? Mines running bad when cold at the money because of it. Definitely the cheaper alternative.

 

I replaced yours in May 09 Jim, but we all know how reliable they are!!

[dr_mat 0]

Well you can tell the difference very very quickly. Either use VAGCOM and read off the error codes or check the measuring blocks, OR open the bonnet and listen .. in my case there was an obvious noise of arcing around the coil pack area ...

[Tekara 0]

Back on all six once more thanks to a new coilpack, can’t seem to spot any visible issue with the old unit - oh well, another expensive round of Corrado ownership :lol: . Hope a new CP solves your issue Jim

[Jim 2]

Seems to have been the coilpack for me too. Met up with Mr Haywire yesterday and we did a fault scan with vagcom first... nothing.

 

Took it for a spin but as the car was warmed up already the fault did not really rear it'd head apart from if you went up into fifth gear at like 30mph.. then it would violently misfire a bit.

 

Came back and swapped coilpacks over with one of kevs spares and car seemed fine and even that misfire had now gone. Subsequently drove to a mates place for the evening and tried the car after about 4 hours when it was totally cooled down and it seems fine again :)

 

Like you Ross, no visible damage to the pack. However did notice a bit of rusty water around the inside casing when Kev dismantled the old one so wondering if water had got in and corroded one of the coils...?

 

Big thanks to Kev for sorting this out for me. Legend! :)

[Kevin Bacon 5]

Nice one Jim, glad it solved the problem!

 

I was reading up on Motronic last night and it has load and RPM variable dwell on the coils, i.e. variable spark strength.

I think putting your foot down in 5th at low rpm kicks in a stronger spark. Your coilpack was clearly on the ragged edge and could only sustain a weaker spark.

 

Anyway, here's what we were discussing with Vince mate about the Ford EDIS coilpack - http://forums.vwvortex.com/showthread.php?4223032

 

FourSeasons tuning sell ready converted Fordwagen leads for the job! http://fourseasontuning.com/?product=834

[Yandards 0]

Nice one Jim, glad it solved the problem!

 

I was reading up on Motronic last night and it has load and RPM variable dwell on the coils, i.e. variable spark strength.

I think putting your foot down in 5th at low rpm kicks in a stronger spark. Your coilpack was clearly on the ragged edge and could only sustain a weaker spark.

 

Anyway, here's what we were discussing with Vince mate about the Ford EDIS coilpack - http://forums.vwvortex.com/showthread.php?4223032

 

FourSeasons tuning sell ready converted Fordwagen leads for the job! http://fourseasontuning.com/?product=834

 

It's also true that higher engine loading (at low RPM in high gear) will highlight any weakness in the spark system, couple that with the lower temperatures and you a receipe for electrical failure.

 

My GT6 that is (still) in 2ccs garage had a similar issue, fine when cold but would cut out when hot. Rotor arm and dizzy cap looked fine but it turned out to be a hairline fracture in the rotor arm, as it warmed up short through the dizzy and no spark.