2006 5.4L Intermittent Dead Miss

[bskouby]

I don't think I like this club.

For giggles I reverted the truck back to the stock tune tonight. Ran like a champ. In fact, it has never ran this good on stock tune before. However, I did change the fuel filter and cleaned the MAF sensor a few days ago. But I sure miss the power.

I will still check all of this out this weekend, not that hard to look at everything again. But I am really starting to think there is something else going on here.

If I figure it out (wishful thinking) I will be sure to post what I did.

[bskouby]

Well...I may have made some progress on this issue. Yesterday I pulled the COPs and spark plugs. I was thinking if I was suffering an actual misfire, I should be able to see some evidence on the plugs. Seven of the eight plugs all looked good. Just a bit of carbon buildup on the shanks, porcelain insulators, electrode, and ground strap all looked good.

The plug in question was from cylinder 5. I noticed that when I pulled the plug it was not as tight as the rest. It is possible I didn't get it torqued down all the way when I replaced plugs 5000 miles ago.

Anyway, the shank was completely covered in carbon build up, in fact there was even carbon on the seat of the plug all the way up to the first threads. So, that can't be good. That aside, the electrode and porcelain looked good. I cleaned the plug in question and put it back in the same cylinder with the same COP.

I also noticed that my battery need to be replaced. The little green window was no longer green, the dreaded red ball had made an appearance. I have been keeping an eye on this for a few weeks, I noticed that the battery had seemed a bit weak on start-up.

With cleaned and re-torqued plugs, reseated COPs, and a new battery the truck is running great on the custom tune. Maybe between the iffy plug and weak battery it was enough to cause a misfire when pushed.

I don't know if the problem will come back, but I figure I found enough things to fix on the truck to make a difference. The jury is still out, but it is looking good so far.

[lbjailer]

If you had a miss-fire wouldn't it be there even without using a tuner? But if that fixes your issue, let us know.

[bskouby]

Originally Posted by lbjailer

If you had a miss-fire wouldn't it be there even without using a tuner? But if that fixes your issue, let us know.

The truck would only misfire when running on the custom tunes. Stock, tranny only, and the canned tunes did not exhibit these symptoms. I wonder if the tune stressed the ignition system enough to not be able to keep up due to the battery and/or possibly loose plug. Only time will tell.

[Lariat4x485]

Originally Posted by Lariat4x485

I have been having the same problem. At about 55 - 60 mph my truck starts shaking, engine light turns on. After that i read the dtc, I had 2 trouble codes. The first one said Cylinder 8 Misfire and the second that there was an error reading the trucks computer. I cleand my air filter, change fuel filter and tomorrow im changing the spark plugs and the connector. Any helpfull info what might be wrong???? Thanks in advance..

Well i had the spark plugs change and the coils. After done that my truck is like new. I have been using it for 3 days now the problem was fixed.