Hey guy’s, wanting to see if I can get some help before I take my truck to the shop. I have a 1998 F150 4X4 SC 4.6l. The engine has just begun to miss mostly at part to mid throttle under a load. The miss is a very noticeable but does go away as you accelerate. The only thing I have done recently was refuel it and take the SuperChip out to have Mike reprogram it. I initially thought that I had some water in the fuel but after the fuel additives, I am still having the same problem with NO check engine light. The MAF is new (6 months old), and I don’t know the condition of the TPS, again, I noticed it on the way to work in the morning after refueling the night before. Any suggestions would be GREATLY appreciated.

[This message has been edited by AH-64MTP (edited 01-29-2001).]

 

^^^^^^

 

AH-64MTP,
I had a similar problem on my F150. Once I changed spark plugs the miss went away. I had never changed my plugs - 1997 F150, 76000 miles. I went with the Bosch Platnium +4's. Probably no necessary, but I wanted to try them out. The gap on the old plugs was 0.080's! I have also seen arching plug wires cause this problem. You did disconnect your battery for at least 5 minutes after pulling the SuperChip, right? To reset the computer. Hope this helps.

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1997 F150 black Flareside, 4.6L, 5 speed manual, Flowmaster Series 40 muffler, Bosch Platnium +4 plugs

 

It sounds like plugs or wires if its happening during mid range RPM's

 

I had a similar problem with my 99 5.4, it idled rough, skipped bad on acceleration, but was Ok at speed.....it ended up being a bad cylinder coil, replaced free under warranty.