Only just got home. VR6 misfire

[Jim Bowen 1]

Just went out in corrado, ran fine, filled up with fuel and then about 5miles after that i got a misfire that just got worse and worse.

 

Any sort of acceleration and it was popping and banging like mad and no power and strong catalytic converter smell.

 

Managed to get the 15miles back home, but very nearly stopped and called AA as it was nearly undriveable.

 

Literally 500 meters from home it seemed to clear up.

 

The fuel may be coincidence, my first thoughts were coilpack, but had that before and never misfired that bad.

 

About to change the engine and also go obd2 but would like to find the fault and fix that first

[Jim Bowen 1]

Will do vagcom tomorrow night.

[ben_wooduk 0]

Does sound familiar to when my coil pack went too

[fla 9]

Silly question but are the leads in the right sequence?

[Jim Bowen 1]

Yeah they have been untouched for ages

[fla 9]

Pull the plugs out and see what they look like. It'll help you diagnose the specific fault by cylinder

[fendervg 32]

Last misfire problem I had was a faulty spark plug, so definitely check/replace them as your first point of call.

[Jim Bowen 1]

Just been out again and was fine for about 10mins and then started the misfiring and popping.

 

Think i can see some damage on the coilpack, was too hot to pull the lead off so will check that tomorrow. Looks as if one of the lead connections that come off it has melted around the base. Definitely looks different to the other 5.

[easypops 8]

I had 2 misfires I can remember. First was when I went through a big puddle, the coil pack was sparking like a firework, no drama up to that point but as soon as it got wet it was comedy. 2nd one was intermittent, turned out the rear centre lead wasn’t seated correctly on the plug

[Jim Bowen 1]

Not sure if this is sign of something wrong, one is different color slightly

 

 

The connector directly below it has a grey white residue in it

 

 

Seems very slightly deformed where is meets the body of coilpack. Slightly dipped

 

 

I wonder if its shorting out between those two points

[ben_wooduk 0]

Sorry, off topic but are you using photo bucket? I thought they didn't allow forum posting etc????

[Jim Bowen 1]

Yeah, it seems it been sorted somehow.

[easypops 8]

I’d put it back together, fire it up and give it a light water misting, in the dark you’ll soon see if it’s shorting, probably will hear it as well

[Jim Bowen 1]

Tried the water misting and couldn't see any sparks. Have had that in the past and couldn't see it this time.

 

Just changed the spark plugs and the coilpack and it's still doing it. Going to eat dinner and give it a scan with vagcom.

 

Pulled the maf wire out while engine was running and hardly noticed any change in the revs etc. Is that a sign of something

[vw rule 19]

Hi Jim have a read of the thread in the attached link below, it might help as it gives good info on the MAF sensor.

http://the-corrado.net/showthread.php?4438-VR6-MAF-problems-(or-not!)-the-saga-continues

 

Robbo149 posted up in the above link back in 2004, think he possibly had a fault / problem with his Cam Position Sensor.

 

Si

Edited October 3, 2018 by vw rule

[Jim Bowen 1]

Cheers for the reply, i did have a can sensor issue in the past and turned out to be the pick wheel on the cam sprocket was damaged, so hoping that's all ok now.

 

Nothing showed up on vagcom. Just an abs pump issue which gives me something else to worry about. :lol:

 

Also the foglights front and rear stopped working while i was turning them on, so that's another thing to worry about :lol:

 

I have been having a weird idle where it surges with electrics being turned on, like headlights or engine fans coming on. With the hazard lights on you can feel engine pulsing in time with the flashes. Considered buying a new battery.

[Jim Bowen 1]

Also i pulled the spark plugs out and from looking at them guides they seemed to have carbon deposits. Which fit with the symptoms

[vw rule 19]

Cheers for the reply, i did have a can sensor issue in the past and turned out to be the pick wheel on the cam sprocket was damaged, so hoping that's all ok now.

 

Nothing showed up on vagcom. Just an abs pump issue which gives me something else to worry about. :lol:

 

Also the foglights front and rear stopped working while i was turning them on, so that's another thing to worry about :lol:

 

I have been having a weird idle where it surges with electrics being turned on, like headlights or engine fans coming on. With the hazard lights on you can feel engine pulsing in time with the flashes. Considered buying a new battery.

 

Jim how did you fix the pickup plate for the cam sensor, did you fit a new sprocket or were you able to bend it back into shape / alinement ?

 

Your fog lights could be a fuse blown or possibly a reply ?

 

Your issue with the engine surging in rhythm with the hazards, could possibly be a bad earth somewhere or like you say a weak battery.

Jim check your charging rate coming out of alternator, then check the charging rate across your battery, erm you should have 13.5v to 14v.

You'll normally see slightly more voltage from the back of alternator compared to that across the battery, but they shouldn't be that far out.

Also check the battery voltage with engine switched off, you should see at least 12v or just under, if you see the voltage continuing dropping down to 11v or 10.5v or even lower on your multimeter, then chances are your battery is going.

 

Si

[Jim Bowen 1]

I fitted a new cam pickup wheel, which aren't that easy to find these days.

 

Am hoping the fogs are an unrelated thing, will check the wiring inside the fog lights, i suspect its shorted out and blown a fuse.

 

Got this from vagcom lastnight

 

Where is says battery voltage at 12.58v, should that be higher with engine runing? or does that reading not account for the alternator charging it?

[vw rule 19]

I think your battery voltage should show as 14v to 14.2v max on scanner with engine running,

unless on VAGCOM it just shows battery voltage at diagnostic plug.

Jim double check your charging rate out of alternator with a multimeter, just to be sure.

 

Si

[vw rule 19]

Jim I've just connected up my scanner which is (AUTEL MAXIDIAG) to my VW Polo and in live data that shows 14.2v to 14.3v with engine running.

 

On your VAGCOM it should show the same as above in live data, unless like I say it only shows battery voltage at diagnostic plug ?

 

Si

[Jim Bowen 1]

Ordered a new battery now, the one i have is around 5yrs old and did sit about for 2yrs while i did work on the car, (i did charge it every few months)

 

I measured the voltage at battery not too long ago and i get

 

Engine running with fans on = 12.85v and slowly falls, without the fans on i got 13.75v. Starting to think its alternator, which is a shame as thats not too old and cost me about £300 (might take it off and take that to the place i bought it from, hoping they can rebuild it)

 

Do you think this could be causing the misfiring etc

[vw rule 19]

Jim your alternator you can get overhauled for roughly £60 but depends where you take it to of cause.

Regarding your battery if it's low on charge or loosing charge, that can cause some of the electrics to do crazy things including some of the engine sensors to not send correct signals to ECU, or sometimes the diagnostic scanner may not read the ECU correctly due to erratic voltage so to speak.

 

Jim I'd get the alternator / battery sorted first, then do another scan when you've got correct voltage.

 

Si

[Jim Bowen 1]

Cheers for your help, think i'll take alternator off this weekend. Seems the best place to start

[vw rule 19]

Jim I think you can either go for a standard battery which will normally have something like 330 to 450 cold cranking amp's (CCA)

Or for a few ££ more you can get a heavy duty battery which will have roughly from 490 to 600 (CCA)

Your old battery should say on the top or side on the label, what the Cold Cranking Amp is.

 

Si