vr6 misfire-million to one?

[bananawhip 0]

Right I will personally make a blue peter badge out of sticky back plastic for whoever can help me conclude my vr6 conundrums...

 

I blew up my old engine and upon fitting a new one I replaced the plugs but kept my coil pack, drove it for 20 minutes with no problems until I parked up for a few days to fit my schimmels (with a new cam trigger)

 

Upon refitting it went very strongly but within 5 minutes had developed an intermittant but very severe loss of power and misfire. This continued for around a week but as it ran so well at times I ruled out timing and put it down to crap leads.

 

I fitted a new set from dubsport with no difference so investigated further, turns out no spark on cylinders 2 and 5 so obviously it pointed to my coil pack, more then likely exposed to excessive heat damage from my previous engine.

 

I fitted a brand new coil pack which made no difference!!!

I have tried various plug, lead, and both my coil pack combinations but 2 and 5 just won't fire.

 

What I want to know is have I come across a 1 in a million chance where my new coil pack is faulty and won't fire on the same cylinders as my old one, or is it something else?

 

as u can imagine with a new engine and cams I'm desperate to use all 6 of my cylinders, any help would be hugely appreciated

[Bruno 4]

Im not convinced it is your coil pack. Coil packs break down when there is either a serious change in engine bay temp, or change in humidity, usually limited to a specific rev range. When I've had catastrophic loss of revs, its always turned out to be something else.

1. Check the relays for the ECU, Ignition and fuel pump.Open them up and make sure theres nothing wrong there.

2. Get a VAG-COM on the job. Local lock up garages can do it for about £20 a pop.

3. What you describe is a classic side effect of the cam sensor, or a cam sensor faulty in combination with an intermittent lambda probe signal. But thats only my opinon.

4. It might be worthwhile double checking that you dont have a spark on 2 and 5. Have you tried using a visual system, ie a proper ignition lead tester? They are available for about £8. Dont use the Draper or one like it, the best one Ive found looks like a spark plug with a clamp on the side to allow one to attach it to an earth.

[bananawhip 0]

thanks for the reply...

 

Using any of the combinations I mentioned above I could literally put my finger in 2 and 5's ht leads and not get a shock.

 

It makes absolutely no difference whatsoever when I take the leads off with the engine running, I've taken both plugs out and turned it over to visually check for spark and also used on of those tester light jobs (although not as good quality as the one you recommend)

 

I'm 100% convinced it isn't firing on those cylinders and it isn't just a case of crap running due to a faulty lamda. Would a faulty cam trigger cause this? It was a vag one.

 

Also would vag-com tell me exactly which sensor/component was at fault or just give me a rough idea?

 

Thanks again

[Toad 0]

It would give you a pretty good idea. Shame I'm not closer or I'd pop over with the laptop.

 

Think Corozin might have VagCom and he's a local....

[Jim Bowen 1]

some interesting points made in this thread here i just found

 

http://forums.fourtitude.com/zerothread ... id=3558363

 

once guy talks about the alternator can cause running probs?

[Jim Bowen 1]

^^^ if that thread solves your problem do i qualify for the badge?

[bananawhip 0]

toad- thanks for the offer mate, haven't heard of that garage but I'll definately look into it, always nice to come across somebody local who knows their stuff.

 

3corsameal- that thread gives me a lot to think about and you may very well of won yourself a shiny badge...

Although my c turns over just fine my battery has probably deteriorated from sitting after I blew my engine. Also when I fitted the new engine I fitted an underdrive crank pulley, do you think this combination could be robbing me of enough power to spark 2 and 5 on my coil?

[dr_mat 0]

Try another ECU. It has an output trigger which goes directly to the coilpack to fire that coil - if that dies you will get no spark.

[bananawhip 0]

Try another ECU. It has an output trigger which goes directly to the coilpack to fire that coil - if that dies you will get no spark.

 

I have a performance chip that I'm not currantly using, if I fit this would that be enough just to check or should I get my hands on a whole new ECU do you think?

[dr_mat 0]

I have a performance chip that I'm not currantly using, if I fit this would that be enough just to check or should I get my hands on a whole new ECU do you think?

 

I meant the ECU, not just the chip. Though I guess the chip might have a bad map for cylinders 2 and 5 I find it unlikely.