99 f150 4x4 112,000 ALL STOCK, except brakes,tires
drive to work 100 miles, runs flawlessly. 6hrs later start up to drive home, misfire. thninking it will clean out, nope. get a little worse and service enginde soon light starts blinking, but then goes away. stop for gas and some drygas, this helps 80%, or was it that the fuel pump liked the gas?

2 days later, drive to work 100 miles, runs perfect. 5 hrs later drive to dads house 100 miles. fine. leave his house to drive home, misfire. now im down to quarter tank of gas, which gets me thinking, it might be the fuel pump getting hot. I am going to do plugs, wires soon. Im going to take to autozone to get a readout.

 

I'll be interested to know what the readout says, but maybe you have water in your gas tank (is that what drygas treats?)...or loose baffles which are affecting fuel flow....maybe a flow test is the next test.

Do you have dual tanks, and if so, does the problem happen only on one tank?

 

It's a misfire code for sure - I'm betting it's #4 lol - anyone else?


With that many miles on them and the kit being so cheap - I would buy the kit off Kevin ($130), comes with plugs.

Type "misfire" in the search "search this forum" for the link.

Mannn, I'm gonna start selling those one of these days lol..

 

Here is a possibility.
When any motor is stopped after being driven, the coolant pressure rises for some minutes before convection cooling brings the temperature and pressure back down and declines.
When this happens the hoses must be flexable enough the expand with the pressure rise or they stand a good chance of splitting when they go hard with age.
You may be having a leak condition from the heater hoses that comes and goes undetected until you look real close for it at the same time the condition in apt to happen the most.
If you don't look at that time the coolant dries up on the outside and can dry enough to not cause a problem with the boot to plug seal after the engine is started and heats up again.

 

i had a VERY SIMILAR problem, and mine was a coil pack, it was like a 300 dollar fix

 

when i had a cop go out when the cel came on the truck run better its like the computer knows how to make it run better