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.

[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.

[Pete]

Paul is correct about the grease,if all is good should not have any issues.
Not too many have heard this myself included till it happened to me.
Been racing for so long you see a lot of crazy $hit and still learning.
Another thing i have learned is our LT5's don't like those fancy/pricey spark plugs.
Buy a set of regular resistor A/C Delco spark plugs $1.50 each gap .035 try it only $12 if they don't fix it i'll buy the plugs from you.
Never understood why people would spend $10-$20 on one spark plug most of us put 2-3k miles a year no need for 100k mile spark plugs.
The fastest ZR-1's run resistor AC Delco's.

Pete

[SAM/CH ZR-1]

It's correct the LT5 does not need extrem expensive spark plugs, but good ones.

I use in my own and my customer cars the Bosch PLATINUM +4 or those from Brisk LGS serie. They work great, don't cost to much and the trottle response increase noticeable. No misfire.