Welder7018

Im at a complete loss with the missfires... they are driving me insane. Ive replaced Plugs, wires, and coils.... I dont know what else. Only two codes are these.







Ive heard that the Crank Position Sensor can cause this? True?

Jacob.P93

Man you can't just throw money at a problem and expect it to fix it. Lol you just bought all that crap and it could be a 5 dollar sensor. 9.75 times out of ten you can do a process of elimination and narrow it done and go get one part and be done with it. Even if they needed replaced you could've saved money by watching for deals.

Swap coil off of 1 and out it on 2 if it moves that's the cause if not then do the same with the plug. If it still doesn't move make sure your injectors are opening. You can do this with a long metal rod or something of the nature and put it up to it and against your ear and listen you should hear a rapid ticking with the truck running. If that's not it I say a comp test is in order.

Welder7018

No I replaced them one at a time compression on all but #8 is above 125. 8 is 118 or 119 the dial was hard to read. And I have two coil packs not individual coils. The missfire is random not constant. It will missfire smooth out. And missfire. And repeat until I get over 2krpm then it almost goes away.

Jacob.P93

You can switch them rather than replace and that will tell you if it needs to be replaced I know it's packs but can't you still switch the wires from plug 1 to 2? And is it always 1 and 8?

Jbrew

As long as your lowest number was at least 75% of your highest number, -you passed compression.

BUT, the absolute lowest you can have is 123psi.

So yea, it didn't pass if it was done correctly and that's why it's missing.

Welder7018

Yes always 1 and 8.

Z7What

I agree 118 seams a little low. Were all the cylinders tested? What did they read?

Dielectric grease out in the wire boots?

Wayne

Jacob.P93

Have you put some oil in the chamber then tried it?

Jbrew

Yea, there's a procedure here,-

http://www.f150online.com/forums/art...ng-proper.html

j.low

I don't know if this will help but, I've a '97 Scab, 4.6 with 234,000 miles on it. The truck weighs in at about 5300 lbs.
A couple of years ago it started doing what you describe. None of the mechanics I went to could figure it out, it was not consistent, came and went. It never had a code so I lived with it grinding my teeth. Note, I have a California truck since new.
So this year on a Nevada trip, after a hard pull on a hill the check engine light came on. Next was the loss of power. I made it to a big city (yes, there is such a thing in Nevada...depending on what part of the country you live in) and a specialty shop put their analyzer on it, "catalytic converter failure."
My truck has four cats in the system. After $2400 I literally had a new truck I was stunned and learned a lesson.
No way of knowing if this is all or part of your problem but it's worth a shot to have it (them) checked.
Good luck.