Foxing Vectra X25XE V6 misfire issue
Discussion
So, my friends V6 Vectra has developed a misfire.
Easy I thought, checked the leads and they were shot, checked the plugs and they were flashing over, probably due to the leads. Changed them, no joy. Bit of t'internet searching turned up DIS or coil pack issues, changed that. Still misfiring.
Now changed the crank, cam and Lambda on the misfiring A bank and it's still misfiring.
Have read the fault codes and that lead us to the Rear Lambda sensor as it wasn't switching.
Have carried out a comp test on all cylinders and all seem ok B bank 175 +-5 PSI, A bank 190 +-5 PSI. No water in oil or oil in coolant, levels stable and have been for a long time.
So after all that work, a few quid and a bit of head scratching were foxed as to where to go next.
Symptoms are, misfire on A bank (near bulkhead) B bank is spot on. Misfire is 90% of the time, mainly under load, when unloaded, cruise idle etc it seems ok. To me it screams spark issue but have checked them and they seem ok. It did manage to burn out one of the standard plugs when we tried those so it's back on the Iridium ones. Hich I though was a tad stange, would suggest bad spark timing and hence detonation or a lean mix.
Engine has, enlarged throttle body, blended intake crossover, uprated cams and a freeflow exhaust system including cat.
To me, the next port of call was cam timing but I thought I'd see if there was any experience of this on here.
Easy I thought, checked the leads and they were shot, checked the plugs and they were flashing over, probably due to the leads. Changed them, no joy. Bit of t'internet searching turned up DIS or coil pack issues, changed that. Still misfiring.
Now changed the crank, cam and Lambda on the misfiring A bank and it's still misfiring.
Have read the fault codes and that lead us to the Rear Lambda sensor as it wasn't switching.
Have carried out a comp test on all cylinders and all seem ok B bank 175 +-5 PSI, A bank 190 +-5 PSI. No water in oil or oil in coolant, levels stable and have been for a long time.
So after all that work, a few quid and a bit of head scratching were foxed as to where to go next.
Symptoms are, misfire on A bank (near bulkhead) B bank is spot on. Misfire is 90% of the time, mainly under load, when unloaded, cruise idle etc it seems ok. To me it screams spark issue but have checked them and they seem ok. It did manage to burn out one of the standard plugs when we tried those so it's back on the Iridium ones. Hich I though was a tad stange, would suggest bad spark timing and hence detonation or a lean mix.
Engine has, enlarged throttle body, blended intake crossover, uprated cams and a freeflow exhaust system including cat.
To me, the next port of call was cam timing but I thought I'd see if there was any experience of this on here.
Yep, it's a nightmare.
As it's not my car I only get secondhand information about what happens and this is from someone who's not a engineer.
From what I can remember it just started happening. I went through the usual problems, leads were shot so changed those, put a new coil pack on etc etc and tried lots of other things but nothing has ever fixed the crap firing in Cylinder 1.
All I can think that would cause it would be a lack of dynamic compression giving an over rich condition or a spark that is only weak on cylinder 1. If that's possible.
The only other indication I've seen is that it's due to the lightened flywheel that's fitted. The crank signal isn't taken from the flywheel though so I fail to see how this could cause it.
As it's not my car I only get secondhand information about what happens and this is from someone who's not a engineer.
From what I can remember it just started happening. I went through the usual problems, leads were shot so changed those, put a new coil pack on etc etc and tried lots of other things but nothing has ever fixed the crap firing in Cylinder 1.
All I can think that would cause it would be a lack of dynamic compression giving an over rich condition or a spark that is only weak on cylinder 1. If that's possible.
The only other indication I've seen is that it's due to the lightened flywheel that's fitted. The crank signal isn't taken from the flywheel though so I fail to see how this could cause it.
That's what I thought oringally as well.
However, the low compression is on the wrong bank to the affected cylinder.
It's only one cylinder that is suffering and not an entire bank.
The cam belt has been changed since that first post, literally 2 weeks ago now and the misfire is still present.
However, the low compression is on the wrong bank to the affected cylinder.
It's only one cylinder that is suffering and not an entire bank.
The cam belt has been changed since that first post, literally 2 weeks ago now and the misfire is still present.
Steve_D said:
My comment about injectors remains unanswered.
Steve
Sorry Steve yeah just seen that.Steve
I did move injector 1 to cylinder 2 (first one on the opposite bank) and the problem didn't move. Checked all the connections too. They are an absolute bugger to fit on that thing. My V8 AJP rail is easier to refit!
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