Well, it looks as if I have to call on your collective expertise yet again as another problem has recently reared it's ugly head.

My truck now misses, backfires, and hesitates below 2500rpm.

I replaced the coil and wires this past weeky and the plugs about 2000 miles ago (Autolite Platinum Plugs).

It did this a small amount about 6 weeks ago, but went away when I replaced the wires.

I have 82k on the truck now and have replaced the fuel filter 4 times since I got the truck.

I now have to drive the truck with overdrive off on the highway or it stumbles and misses.

It is odd because it is virtually non-existent above 2500 RPM. At RPMs above 2500, the motor pulls stong and responds to throttle inputs instantly.

I was afraid that perhaps the timing chain had jumped, but I don't think it would run smooth at higher RPMs if this were the case.

What do ya'll think?

 

Had the same problem with mine but the plugs, wires, and fuel filter got mine running fine and have had no problems since. Did it all about 6 months ago. good luck.

 

Well, thanks for the reply. I was thinking of doing the plugs again this evening if the weather holds out. I will probably just give the good old stock motorcraft plugs a try and see if that remedies my problem. Hopefully, those AUTOLITE plugs are just crap and this is all that is wrong with my truck.

If anyone else had any input or has had a similar issue but resolved it some other way, I would love to hear from you. I am concerned about VACUUM hose issues and SENSOR isssues as well. I looked at buying a code scanner at O'Reily's auto near my home, but the darn thing was $169. Hard to justify that cost for something I would only use occaisionally.

I need to replace the O2 sensors as well, but am dreading that $240 cost (around here, they are $60 a peice). The Chilton manual and the part's computer only show two, but there are clearly four on that truck.

Thanks again all for your support! Here is to another 80,000 miles. Because aside from having to replace the front brakes every 30k miles (and of course this recent issue), the truck has had no real issues.

Steve

 

Kind of sounds like the EGR system.These 4.2s are notorious for clogging the EGR ports in the intake.Then again,could be your upstream O2 sensors.Go to Autozone,they will scan the computer for free.And the Autolites are just the same as Motorcraft.Good luck.Keep us posted.

 

Well, I fixed it!

Tonight was the first time I have had to remove the plugs and examine them for signs of engine trouble (oil, water, etc.)

When pulling plug # 5, the ceramic top portion of the plug came out in two pieces.. I replaced the plugs with plain old autolite plugs (all that Wal-Mart carried, and all available on Sunday night).

The new plugs went in with no problem and now the truck runs great!


I cannot thank you all enough for your tips and advice! We are truly blessed here to have this resource.