Misfire

[ZRXMAX]

Can't locate the source of a missfire. Under light throttle it runs ok, however, anytime you give it a little throttle it misses on what seems to be one cylinder. I have changed the coil packs back to my old stock ones because they still worked fine when I replaced them. They all show about 6 ohms resistance. Also checked the injectors with an ohm meter and they were all good.

The plug wires are pretty fresh and look to be in excellent condition.

A week ago it was running good and then the number 1 spark plug wire started coming off every minute. It turned out I had accidentally gotten some dielectric grease on the end of the plug. Once cleaned it stayed on.

When I changed the plugs I discovered that the insert in one of my spark plug sockets had stayed on the number 8 spark plug and came out with the boot when I reinstalled new plugs. Since it was the last new plug installed, and, you cant see in the plug hole without a mirror I didn't notice it until I changed all the plugs again to eliminate one possibility for a misfire.

Any suggestions on what to look at next will be appreciated. I have pulled the plenum twice and I am right back where I started. It did run real good briefly until the number 1 plug wire started coming off.

[Demps]

What are the plugs gapped at? I've found they don't always like 0.050". Symptom was stumble at throttle tip in. Easiest diagnosis I found was run it a gear high & ease into throttle. If it stumbles, I change gap to 0.035" & assess.
Ted

[ZRXMAX]

I will give that a try. I had changed to iridium's a while back without a hickup. Like I mentioned, I installed a new set because it was easy and cheap ! I have been watching you tube tutorials just to see what others say about testing basic parts.
Thanks... I hope this does it !

[ZRXMAX]

I re gapped my fresh set of NKGs to 35 and the misfire was minimized a tiny bit. This leads me to believe I might have a bad plug wire. Then again, it was running fine the other day until the number one plug wire started coming off.

Would that wire coming off hurt a coil pack from working normally?

[Pete]

If boot comes off change spark plug.
Leaking thru porcelain.
That will also fix misfire.

Pete

Originally Posted by ZRXMAX

I re gapped my fresh set of NKGs to 35 and the misfire was minimized a tiny bit. This leads me to believe I might have a bad plug wire. Then again, it was running fine the other day until the number one plug wire started coming off.

Would that wire coming off hurt a coil pack from working normally?

[ZRXMAX]

Yes... I cleaned everything with Q tips and carb cleaner to remove any dielectric grease on all 8 a few days ago. Thanks

The other day even when it was running good something about it didn't seem like it normally does. Next time I pull the plenum I will check all the wires.

[Paul Workman]

Originally Posted by ZRXMAX

Yes... I cleaned everything with Q tips and carb cleaner to remove any dielectric grease on all 8 a few days ago. Thanks

The other day even when it was running good something about it didn't seem like it normally does. Next time I pull the plenum I will check all the wires.

It's a pretty safe bet that whatever Pete suggests has considerable merit.

And, I can assure you from 40 years of using the stuff that dielectric grease is NOT going to cause the boots to come off of the plugs. Unless, the boot is flooded with so much to the point the boot can't be seated onto the spark plug, OR there is a leak due to a defective spark plug, as Pete suggested, the boot stays put.

Dielectric grease not only facilitates installation and removal of the boot, but acts as a seal against contaminants that might creep up the sides of the porcelain to the point where "spark tracking" from the electrode to ground along the outside surface of the porcelain insulator may occur.

Besides... There is ample friction between the boot and the walls of the sparkplug hole to secure the boot from slipping from normal vibration. Further, the boots have longitudinal ribs that would tend to vent gasses that escaped around the plug threads - all but eliminating anything but the most severe cases of leaking plugs.

Hydraulic pressure from within, e.g., due to a defective plug, is another matter. In that case, if there were no seal formed by the dielectric grease, the gas might escape undetected. The unintended consequence being to make it difficult to detect perhaps; another argument in favor of the dielectric grease?

By removing the dielectric grease, it seems possible that doing so may have created the chance for additional problems later, while doing nothing to solve the misfire issue.

Your mileage may vary...

[ZRXMAX]

Originally Posted by Paul Workman

It's a pretty safe bet that whatever Pete suggests has considerable merit.

And, I can assure you from 40 years of using the stuff that dielectric grease is NOT going to cause the boots to come off of the plugs. Unless, the boot is flooded with so much to the point the boot can't be seated onto the spark plug, OR there is a leak due to a defective spark plug, as Pete suggested, the boot stays put.

Dielectric grease not only facilitates installation and removal of the boot, but acts as a seal against contaminants that might creep up the sides of the porcelain to the point where "spark tracking" from the electrode to ground along the outside surface of the porcelain insulator may occur.

Besides... There is ample friction between the boot and the walls of the sparkplug hole to secure the boot from slipping from normal vibration. Further, the boots have longitudinal ribs that would tend to vent gasses that escaped around the plug threads - all but eliminating anything but the most severe cases of leaking plugs.

Hydraulic pressure from within, e.g., due to a defective plug, is another matter. In that case, if there were no seal formed by the dielectric grease, the gas might escape undetected. The unintended consequence being to make it difficult to detect perhaps; another argument in favor of the dielectric grease?

By removing the dielectric grease, it seems possible that doing so may have created the chance for additional problems later, while doing nothing to solve the misfire issue.

Your mileage may vary...

Thank you for that detailed explanation on spark plugs. In my life I have never had a spark plug that leaks and blows the boot off.

I will pick up another plug and re grease the boots and see what happens.

I always use dielectric when putting plugs in. I was talking to a mechanic friend of mine and he mentioned I might have gotten some grease on the connector and that might be the problem.

Also... number 7 was misfiring so I put another stock coil pack on it from a low mile Z and it seems to be working just fine now.

Yes... I think my mileage will vary!

Thanks Pete... Thanks Paul... I will update you when I get it done.

[Bearly Flying]

I think you want to use Anti seize on the threads and dielectric grease on the ELECTRICAL connection

[ZRXMAX]

Thanks... that is what I have always done.

Update. I was able to locate another NKG plug to replace the plug that leaked air past the electrode. It wasn't a U Groove plug like the rest ( they didn't have one in stock and I am commuting daily )

It is running about 50% better but still misses alot at idle and anytime below 2500 rpm. Once above 2500 it runs smooth up to about 4000 and then starts to miss again.

Will find a U Groove NKG plug tomorrow and see if that fixes it.

Also have code 24 and 61... will fix 24 first and see what happens after that.

This whole situation is just weird... It appears #7 is the plug that misfires... I ohm checked the wire and changed to coil pack... will keep searching.

Thanks to all.