New plugs, now I have misfire

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Henrik97

Active Member
Posts
301
:(
97 4.6HSE
I replaced my plugs yesterday to rule out the dreaded slipped liner syndrome. I'd had some coolant loss, but it seems it's only the heater o-rings. At least all the plugs looked identical - not one washed off as one would expect if coolant was leaking into the cylinder.
Anyway, the engine was running smoothly before I changed the plugs, but now it seems to be running intermittently on one or more cylinders (rough idle, low power and popping exhaust). There is an audible difference when I remove any lead, so it's not one cylinder completely dead. The HT leads looked very tired and I do suspect that this is the cause, but even in the dark, I cant see it arcing over anywhere.
The plugs I removed were NGK BKR6ES, replaced with NGK BPR6ES. From what I've learnt, the only difference is the socket size. I did not adjust the gaps on the new plugs, but is it necessary?
I will try to replace the HT leads, but any other ideas are welcome.

Thanks!
Henrik
 
you should allways change leads as well as plugs ,sounds like youve got a few leads on wrong plugs ,very few v8s get slipped liners its the ali block that cracks behind liner usually adjacent to head bolt hole allowing combustion gase to pressurise cooling system when engine reaches running temp ,liners sit on a step ,any that do move is either due to cracking relieving pressure on liner ,bad manufacture or seizing
 
Henrik97 said:
:(
97 4.6HSE
I replaced my plugs yesterday to rule out the dreaded slipped liner syndrome. I'd had some coolant loss, but it seems it's only the heater o-rings. At least all the plugs looked identical - not one washed off as one would expect if coolant was leaking into the cylinder.
Anyway, the engine was running smoothly before I changed the plugs, but now it seems to be running intermittently on one or more cylinders (rough idle, low power and popping exhaust). There is an audible difference when I remove any lead, so it's not one cylinder completely dead. The HT leads looked very tired and I do suspect that this is the cause, but even in the dark, I cant see it arcing over anywhere.
The plugs I removed were NGK BKR6ES, replaced with NGK BPR6ES. From what I've learnt, the only difference is the socket size. I did not adjust the gaps on the new plugs, but is it necessary?
I will try to replace the HT leads, but any other ideas are welcome.

Thanks!
Henrik
Click to expand...

Always check the plug gap even on new plugs. Why did you change the plug designation. The new ones may have more built in resistance, with tired leads that could give you a yellow spark.
 
wammers said:
Always check the plug gap even on new plugs. Why did you change the plug designation. The new ones may have more built in resistance, with tired leads that could give you a yellow spark.
Click to expand...
I bought a set of plugs off ebay, for my particular year and model. I have checked, and apparently only the socket size is different.

Henrik
 
As said, check plug gaps! If you dont have one, nip to your local motor factors etc and get yourself some feeler gauges (make sure it has the right size for your car!). Don't take out one plug and assume they are all the same.

Also double check you are actually putting the leads on correctly! I know it sounds daft but it is easy to do wrong.
 
rustyrhinos said:
As said, check plug gaps! If you dont have one, nip to your local motor factors etc and get yourself some feeler gauges (make sure it has the right size for your car!). Don't take out one plug and assume they are all the same.

Also double check you are actually putting the leads on correctly! I know it sounds daft but it is easy to do wrong.
Click to expand...

You said it, mate. DAFT!!!! I found the numbers on the coil pack now in the daylight and guess what...: :clock:I'd swapped cylinders 1 and 3.
Magnecor leads are now on order, but in the meantime she's running beautifully on the old set.
Thanks for the input, and sorry for being such a complete dimwit and wasting everybody's time.

Cheers,
Henrik
 
Henrik97 said:
You said it, mate. DAFT!!!! I found the numbers on the coil pack now in the daylight and guess what...: :clock:I'd swapped cylinders 1 and 3.
Magnecor leads are now on order, but in the meantime she's running beautifully on the old set.
Thanks for the input, and sorry for being such a complete dimwit and wasting everybody's time.

Cheers,
Henrik
Click to expand...

**** happens, we have all done that. Some won't own up to it though.
:):)
 
Henrik97 said:
You said it, mate. DAFT!!!! I found the numbers on the coil pack now in the daylight and guess what...: :clock:I'd swapped cylinders 1 and 3.
Magnecor leads are now on order, but in the meantime she's running beautifully on the old set.
Thanks for the input, and sorry for being such a complete dimwit and wasting everybody's time.

Cheers,
Henrik
Click to expand...

Nice one :D Glad you got it sorted and for admitting to it!
 
I guess the morale is: Have adequate lighting available, keep a clear head and lay off the beer.
Most important: Don't be left in a hurry because you're in a mate's garage and his wife is going bonkers over having his pal's gas-guzzling ****-heap indling roughly beneath her bedroom window.

Cheers,
Henrik
 
Henrik97 said:
I guess the morale is: Have adequate lighting available, keep a clear head and lay off the beer.
Most important: Don't be left in a hurry because you're in a mate's garage and his wife is going bonkers over having his pal's gas-guzzling ****-heap indling roughly beneath her bedroom window.

Cheers,
Henrik
Click to expand...

Closing the window is obviously an option she did not consider. :D:D:D
 
Henrik97 said:
I guess the morale is: Have adequate lighting available, keep a clear head and lay off the beer.
Most important: Don't be left in a hurry because you're in a mate's garage and his wife is going bonkers over having his pal's gas-guzzling ****-heap indling roughly beneath her bedroom window.

Cheers,
Henrik
Click to expand...

Should have got your Pal to go up and pop something in his wifes mouth, that would have kept her quiet for a bit:blabla::blabla::blabla:
 
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