Reading misfires with FORSCAN

[Meadowlark Lemon]

I am trying to hunt down the cause of a rough idle and surging under light load / low speed. I downloaded FORSCAN and recorded some data while driving today. My problem is that FORSCAN only has 6 channels for monitoring misfire counts (NM1 - NM6). Is there a way to monitor #7 and #8 that I am missing somehow?

Thanks,

Andrew

 

[MrQ]

Man, I didn't see that there was more than one misfire monitor on Forscan! That's helpful, albeit if you can find 7 and 8.

Unfortunately, I don't have my OBDII V8 Explorer here to check, so I can't help you with that.

 

[Meadowlark Lemon]

Well, I think I found part of the cause for my misfire on the #4 cylinder - have a look at the attached pictures of the spark plug I pulled out of there. I am surprised it fired at all!! I changed all 8 and many of them had that kind of fluffy looking grey build up - just not as much. Any thoughts on the cause of this? Truck has 185K on it and I have no idea how long these plugs have been in there.

Thanks,

Andrew

 

[Turdle]

Could be just old misfiring plugs ashed over. Run this new set and see what happens after 5k miles. Easy enough to check a few right?

Here's a chart I found

EMSK How to read spark plugs : everymanshouldknow

 

[beepinX]

Wow that was toasted! Have you checked other plugs? We'll be working on buddy's new truck project '97 Explorer right after we finished installing the headache rack on the current dually project. Explorer has been sitting for about 4 years and used to be driven by an aggressive kid. I wouldn't surprised if its plugs are fried as well.

 

[Meadowlark Lemon]

I did change out all eight plugs, that #4 plug in the picture was by far the worst, but a couple were pretty ashy and a couple had very wide gaps. The truck runs night and day better now. Not only is the idle smoother but the power feels much peppier as well. Definitely time and money well spent, just wish I had done it sooner!

Between the new EGR valve, coil pack, and spark plugs I have been keeping the CEL at bay for a week now. Hopefully it stays that way!