Hi all. Any help please. I have a misfiring problem with the Z, starts fine, runs on all 6 for about 2 minutes, then half a mile down the road goes lumpy and runs on 5. About 2 miles later runs on 6 again.

 

Up to 0.4 bar boost it pulls ok, anything more and it starts juddering violently, no pull at all. Revs freely at stand still across the band, fine.

 

Have cleaned the PTU connectors (and all others I could see) one was green, and it did seem a little better after that.

 

PTU is a series 1, relocated behind passenger headlamp.

 

Any advice appreciated, cheers :)

Did you relocate it or was it already done? Has it always had the problem or has it just started?

yeah, and did the re-location entail modification to the loom and have you checked those connections....

I have a spare Series 1 ptu, could get it to you to check .....

A faulty ptu can cause misfire issues but have you checked the maf, coils and injectors as well?

It was relocated before I bought the car about 4 years ago, done by a member here so I think it was a good job. Started playing up a few months ago, but I don't do much mileage now so haven't been flooring it.

 

I'm gonna check the maf today, don't know how to check coils or injectors properly, but the problem seems quite severe that it's probably not an individual coil I thought.

 

Medallian Man, I'm gonna look for any modification to the loom in a min, if I could remember the guy's name who had the car before (black swb ADZ194) I could have asked him (he's been posting on here for years). Thanks for the offer, I'll see what I can discover this afternoon and get back to you on that, cheers :)

Just an update to the misfiring problem, now solved.

 

After spending months searching for it and checking everything, I feel quite stupid now because it turned out to be a spark plug. I didn't know they could break down, when I checked them before they all looked clean and correctly gapped, so I put them back in.

 

Luckily the misfire became less intermittent this week, so I located it to front o/s cylinder and thought it would probably be a dodgy coil pack, but thought I'd try a spare spark plug first, and vroom smooth again :)

 

The dodgy plug was a NGK PFR6B 11C, can't imagine many of them break down.

oooh might try changing my sparky on number 4 cylinder and see if that sorts out my idle misfire i have. glad you got it sorted though matey