VR6 - not firing on all 6

[crazymarcel 0]

Damm car, was driveing along quite happily when its kinda like changed and now feels like its not firing on all 6, performance has gone, judders loads, got it home alright. :mad:

 

Any ideas what this could be anyone?? Coilpack??

[Ady_G 0]

That happened to mine about 6 months ago and it was the plugs, they had got all oiled up on cylinders 1 and 6. I changed them for standard NGKs and it's been fine since.

 

Cheers

 

Ady

[Kevin Bacon 5]

Could be your plugs or coilpack as your leads are recent according to one of your posts, although it's been dry and sunny today in our area....so unusual for a CP to misbehave on a dry day unless it's *really* buggered.... It's worth checking the leads to make sure they're on firmly too.

 

Oil fouled plugs is not a good sign! All 6 should look like this......i.e. uniform in colour with no oil deposits.

 

K

[crazymarcel 0]

The plugs are only three/four months old, although i have not checked these, I'm thinking coil pack.

 

Its worse when the car is warmed up, and is worse at lower revs around 1900rpm. and u can hear the exhaust like makein a putting sound, like unburnt fuel at idle.

 

Its been dry here too kev until i jetwashed my car.

[corradovr6sc 0]

could be the maf. Mine has the same symptoms and vag-com reported a dead maf. Check the coilpack for arcing.

[crazymarcel 0]

The MAF is less then 6 months old.

 

How do i check the coilpack for arcing?

[crazymarcel 0]

I checked one plug and seems alright and i'm thinking if it was the plugs all oiled up, surely it would effect it starting more and would get better as the car warmed up, rather then the opposite.

[corradovr6sc 0]

spray a mist of water over the coilpack at night whilst the engine is running and if there are cracks in the plastic insulation you should see blue flashes. If the coilpack is arcing you can repair the plastic with epoxy glue. If you do a search there are threads on how to repair the coilpack.

[Bruno 4]

not firing on all 6, performance has gone, judders loads

 

Given that your plugs and MAF is fine, you have three options available.

1. Most likely : coilpack. Warm the engine up. Wait until dusk. Spray some mist over the coilpack. If it fizzes or produces a nice display, replace it. Do check the archives here about which one NOT to buy!

2. If not that, disconnect the battery for a couple of hours. Reconnect and, after warming the engine, drive the car like a horse with a demon in its belly for 10 mins, then toodle about for 10 mins. Stop and let it idle, if the lumping clears at any time in this process, then you need to pull the O2 sensor from the CAT, clean it gently, replace it. also clean the blukhead junction points where the O2 sensor lead links to the normal loom lead.

3. If not that, is your engine radiator fan behaving badly? Ie your car seems to get too damn hot and the fan, when it gets around to kicking in, goes like the blazes, as though its auditioning for a jet engine film role? If so, get your car in to be checked by a VAGCOM analyser and see if your ECU is reporting a cold temperature feed. If so, check the cables and each temperature sensor and if these are all fine - you are unfortunately left with the ECU.

If you are really now facing the option of an ECU problem one way of confirming this is :

- somebody ran your car thru a very large puddle recently and washed the engine bay. the ECU does not like getting wet. I know, I know.

- somebody decided to steam clean the engine bay without bagging the ECU and other key brains and the coilpack. that guarantees the little devils will get their own back for getting so wet!

 

Probabilities: 1 in 800 cases go to ECU, 1 in 40 go to coilpack, 1 in 20 have a temperature sending problem.

 

Hope this helps

[crazymarcel 0]

Cheers for the info Bruno, I'll look into it more if new coilpack and plugs doesent solve it.

 

Advice needed on coilpack.

 

German & Swedish price is £117 Includein vat made by Beru

VW original part is £220 Includein vat - dont know who its made by.

 

I been told the beru ones arent that good, but for a hundred quid more is the vw one that much better?

[Kevin Bacon 5]

Wear rubber gloves if you're working on the O2 sensor as I've read somewhere that you're not supposed to touch them, probably why new ones come with a sleeve covering the tip.......which I bet some people forget to remove, LOL!

[Gaz154 0]

is oil on the plugs bad if its on the threads but not near the tip

or is it on or around the tip thats bad

my 93 vr6 has an intermitant starting problem turns over but wont fire up starts with a bump start which i know is bad

then it smells strongly of fuel for a while when it fires up

[dr_mat 0]

My VR starts fine, but also smells of fuel for a very short while, 5-10 seconds or so.. I've heard that overhauling of the injectors can help with starting problems and petrol smells..

[crazymarcel 0]

All sorted now, well chuffed.

 

New coilpack and some plugs and its running better then ever :)

[Kevin Bacon 5]

Oil on the threads isn't a major concern, probably due to a previous or current rocker gasket leak but oil on the plug tips is definitely a bad sign.

 

Mine used to stink of fuel and run badly upon startup but I discovered my black Carbon canister hose had a split in it where the airbox had been rubbing on it. Replaced that and no more stench and perfect starting & cold running.

Also check the clear CC hose where it joins the tank outlet pipe under the brake servo. This pipe becomes porous with age as do the two black hoses that join the fuel rail.

 

K

[dr_mat 0]

... the black carbon canister hose ...? Enlighten me if you would kev, with pictures if poss - cos I'm a bit thick like... :)

 

I wouldn't say I have any cold running problems though, so maybe it's not too bad.

[Kevin Bacon 5]

Yeah the black hose runs under the airbox (as does the clear one) and joins the blue frequency valve strapped to the strut tower. The black hose also runs alongside the top left corner of the airbox (looking in from the front of the car) and it's here where you can get rubbage!

 

My smells were a combination of a split in that hose and a seeping clear hose (CC input) at the join under the brake servo.

 

My VR pulls like a train when it's cold now, so that leaking hose must have created a nasty air leak!

 

HTH

 

K