hey guys, I have a 97 4.6 4x4 expy and about 2 months ago I had a misfire in cylinder 1, so being around 100k I replaced all the plugs. Everything was good then about a month later I got another misfire.. truck running real rough and check engine blinking.. it was a misfire in cylinder 7. Fixed that plug everything was good now 3 weeks later..I was out last night and everything was fine. Started her up this morning got 2 blocks away and she felt rough.. then the blinking check engine light came on and I could feel the misfire.. I'm going to scan the truck after work and see what is wronge this time.. but any idea's? anything else I should look into? thanks for any info.

In other news I had 2 friends totally rebuild the rear of my truck all new gears, pinion, seals and bearings and it cost me $500.00 bucks for the parts (luckily we ordered them through my friends shop) and they fixed it for nothing. The ford dealership wanted 1800 bucks for the job, and we tried calling a junkyard to just swap rears but they wanted 900 bucks for the used rear.

So I was all happy my truck was running good.. till today! damn this thing is going to make me poor.

 

Did you replace the plug wires? Mine held up until about 75,000 miles, then Misfire City, complete with blinking CEL. I did the plugs and wires, everything turned out fine.

 

i'm going to do them today along with a new plug for whatever cylinder is misfiring.. hopefully that gets it. then whats left the coil?

 

Possibly. I can't recall if cylinders 1 and 7 are serviced by the same coilpack.

 

https://www.ford-trucks.com/

 

I had the same problem with my E150 - run fine one day, then the next, when I started it up, it was misfiring something terrible. After 5 trips to 2 different dealerships and nothing wrong was found, the mechanic asked me what kind of gas I was using, I normally use various brands, but when he said don't use BP, it all came clear. The last time my engine misfired was a couple of days after I put BP in it. The mechanic indicated BP puts an additive in their fuel (I dont remember what he called it) that will coagulate on the injector nozzles after the engine cools down. When starting it cold, one (or possibly more) of the injectors was plugged with this additive, preventing fuel from entering the cylinder, causing the misfire. Then my SERVICE ENGINE SOON light would come on. After a short distance, 2 to 4 miles, the problem would clear up. By the time I got to the dealership, the engine was running fine, even though the SERVICE ENGINE light was on and the misfire code was stored in the computer, the dealership could find nothing wrong. I had a Chevy a while back that did the same thing, and a mechanic at the Chevy garage told me the same thing.

I stopped using BP and have not had the problem since. Perhaps this may be causing your problem as well. Hope this helps and would like to know if you switch gas your vehicle runs fine.