Misfire... Thoughts?
Discussion
Old Bruce has developed a misfire of late.
The ECU hasn't picked up anything, checked via OBD2 reader and also with EFI Live (I guess that assumes I'm logging the right PID, but Misfire Count Cylinder 1 (Current) seemed sensible...?)
Before I go wild with the scatter gun, I thought I'd ask for some opinions...
Misfire occurs at idle (more so once warm, but possibly just because of lower idle speed once warmed up?) and at load between 1,250 and 1,750 rpm. Higher up the rev range it is absolutely fine.
It has slowly become more frequent, it was initially just an occasional shudder at idle, then it started doing it at low rpm as described after a day at Santa Pod (coincidence?
)
I have also swapped the fuel rails over, although it had completed a lot of miles with them on before it got worse, and was occasionally doing it at idle before they were ever fitted.
My thoughts are:
Coilpack failing?
Possible obstruction of an injector in the fuel rail as these have been played about with?
Injector failing?
Spark plug?
HT Lead?
Car is just about to get to 60,000 miles, serviced at the fish every year so presumably plugs were changed fairly recently as part of a 50k service? I can't remember though to be honest
I was thinking of getting hold of another coil pack and then swap it between the 8 cylinders and see if it clears it up in any position, as this seems the quickest / cleanest / cheapest thing to try as I could just borrow a coilpack for 10 minutes and rule that off the list...
Any thoughts? Anybody with an LS2 near Aylesbury? Topcats up the road have LS3 and LS7 coils to hand and are happy to let me tinker with it in their car park, the internet is trying to tell me that LS7 coils are compatible with the LS2, is this just typical Yank nonsense...?
Any help appreciated
The ECU hasn't picked up anything, checked via OBD2 reader and also with EFI Live (I guess that assumes I'm logging the right PID, but Misfire Count Cylinder 1 (Current) seemed sensible...?)
Before I go wild with the scatter gun, I thought I'd ask for some opinions...
Misfire occurs at idle (more so once warm, but possibly just because of lower idle speed once warmed up?) and at load between 1,250 and 1,750 rpm. Higher up the rev range it is absolutely fine.
It has slowly become more frequent, it was initially just an occasional shudder at idle, then it started doing it at low rpm as described after a day at Santa Pod (coincidence?
)I have also swapped the fuel rails over, although it had completed a lot of miles with them on before it got worse, and was occasionally doing it at idle before they were ever fitted.
My thoughts are:
Coilpack failing?
Possible obstruction of an injector in the fuel rail as these have been played about with?
Injector failing?
Spark plug?
HT Lead?
Car is just about to get to 60,000 miles, serviced at the fish every year so presumably plugs were changed fairly recently as part of a 50k service? I can't remember though to be honest
I was thinking of getting hold of another coil pack and then swap it between the 8 cylinders and see if it clears it up in any position, as this seems the quickest / cleanest / cheapest thing to try as I could just borrow a coilpack for 10 minutes and rule that off the list...
Any thoughts? Anybody with an LS2 near Aylesbury?
Topcats up the road have LS3 and LS7 coils to hand and are happy to let me tinker with it in their car park, the internet is trying to tell me that LS7 coils are compatible with the LS2, is this just typical Yank nonsense...?Any help appreciated
monkfish1 said:
Almost certainly a plug or lead issue.
He's right you know! I had misfire issues for quite sometime and had to change wires almost as much as I fueled up. I have aftermarket headers so the wires were being heat damanged. I ended up going with some accel ceramic coated HT leads and no more issues. minime68 said:
He's right you know! I had misfire issues for quite sometime and had to change wires almost as much as I fueled up. I have aftermarket headers so the wires were being heat damanged. I ended up going with some accel ceramic coated HT leads and no more issues.
had mine for 4 years, great HT leadsminime68 said:
He's right you know! I had misfire issues for quite sometime and had to change wires almost as much as I fueled up. I have aftermarket headers so the wires were being heat damanged. I ended up going with some accel ceramic coated HT leads and no more issues.
had mine for 4 years, great HT leadsSturdyHSV said:
OK, sounds like concensus is plugs/leads then
I'm relocating the coilpacks so will be making up some MSD leads, so hopefully that'll fix the problem...
Plugs probably worth doing though, any particular plugs to go for with a bolt on NA motor?
Thanks all
Alright final offer 2000 given the cars got problems lolI'm relocating the coilpacks so will be making up some MSD leads, so hopefully that'll fix the problem...
Plugs probably worth doing though, any particular plugs to go for with a bolt on NA motor?
Thanks all
mikeyb1987 said:
Alright mate. The misfire sounds quite serious and very difficult to detect what the issue is.
Maybe you should undertake a full top-end rebuild- you know, heads, springs, valves, cam, rockers.
Hope you get it sorted easily mate
You've got a point ill go back to my previous offer ill take it as it is for 1500 quidMaybe you should undertake a full top-end rebuild- you know, heads, springs, valves, cam, rockers.
Hope you get it sorted easily mate
SturdyHSV said:
Tattooboy said:
Have a few LS3 OEM leads spare if you want to swap a few out to try ??
Presumably they fit, so if that's not a hassle that'd be great! Will get you a bottle of rum or something PM me your address and I'll post them off Monday, think there's 5 in the box as 1 broke when fitting the headers and I broke another one when I fitted the new set.
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