Hey all. I have a 98 f 150 5.4. Have changed all the plugs and cops out and still missing very badly at any rpm. Also changed the cam position sensor. Not getting any codes. Cant afford to keep throwing parts at this thing. Any suggestions? Was giving a code po302, and po118. Also i replaces the cyl head temp sensor cause apparently at one time a rat or something made a nest under the intake and chewed the wire harness at the sensor off.

 

What brand plugs and cops did you use? Did you use dielectric grease in the boots? Have you tried some injector cleaner in the gas (Techron is the best)?

 

You need to test to see if you're actually getting spark out of the #2 coil, you could have a wiring issue

 

I used duralast coils and mortorcraft plugs.yes i used dielectric grease in the boots. Havent tried injector cleaner yet.

 

Duralast coils aren't very good. Too bad you didn't order a set of Visteons off Ebay for 160 bucks.

 

Ok so heres where i am now. Just ran some injector cleaner through the engine. It started to run a little smoother so i started going down the line disconecting one cop then injector. Got to cyl 3 unplugged cop and nothing... unplugged injector and a little difference was noticed.. any suggestions..

 

Just get the right coils, - before all your hair falls out. They, cheap. Get them while you can, because they come and go. Visteons or Motorcraft. Visteons are money well spent. Do that and it will purr like kitten and feel like it lost 1500 lbs.,- when you hit the go pedal.

Here, hit this, -

http://www.ebay.com/itm/FORD-E250-E350-E450-E550-VISTEON-IGNITION-COIL-DG508-ALL-8-BRAND-NEW-/181107124114?rt=nc&_trksid=p2047675.m1851&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D163%26meid%3D7313448217986380945%26pid%3D100005%26prg%3D1088%26rk%3D1%26sd%3D170998096349%26

 

Even if you get it to fire on all 8, the truck will feel like a slug, unless your purchase healthy coils.

You bought low tech coils, you most likle have more than one just working half a$$.

Here's why, -

 

Ok i understand that but i took the coil and the injector off of cyl 3 today and swapped them with the #1 cyl and same thing happens on #3. Come to find out the mechanic that changed plugs for me a few months ago put a helicoil on #3 plug. Thinking maybe loosing compression.. gonna check tomorrow.

 

Helicoils do not last. You may have to dig it out and replace it with a Timesert or a Bigsert.

 

Also, swap plugs with 3 and 1 and see if it moves...possible bad plug?

 

It doesn't work like that usually. It'll keep freaking out like domino's. Your gonna do a bunch of stuff until something half way makes sense, then go thru the trouble. IF lucky, it might run better for a little while, - BUT IT WILL happen all over again with cheaply built coils.

 

Ok jbrew. So what your saying is that i should go ahead and replace the cops with visteon coils before worring about compression testing #3 cyl? Ive read alot of different threads on this site and you seem to know your stuff. Im a shadetree mechanic at best and not the best at that but im definately not afraid to get my hands dirty. So you tell me the next logical thing to do and ill give it a shot im all ears..

 

Okay, but you better listen

I've had to rebuild that harness as well lol. Being a 98, wires begin to separate inside the insulation and you can't tell from the outside. So anything in question, - tap the wire further down, past as many bends as you can then check continuity from there to the connector blade. Use a pin to tap the harness unless you have a better way. A sewing needle works well.

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Missing bad at any rpm's ? Alright, your harness dips down above the AC accumulator. With a lot of these trucks, the wires at that particular loop bare or loose their foil wrap. That causes a magnetic interference and ignition havoc. Sometimes you move the harness away from the accumulator and the miss will go away. You have to check that loop out for damage.

If that's okay, and your wires check out, rev the engine up to where it misses the most and hold it there. Watch for the CEL to blink then turn off. If you have to drive it, then do so, just hold at the worst spot. The misfire monitor need to count the number of misses in order to give the cylinder information. If it blinks and shuts off, -DTC is on the KAM KeepAliveMemory and needs to scanned. Don't erase or disconnect the battery.

If you want to further this, then check my sig to comp test correctly.

 

You fixed the 118 right. A 118 isn't the CHT, you know that correct?

P0118 Engine Coolant Temperature (ECT) Sensor 1 Circuit High