4.6 misfiring, light blinking going down the road. so i took it to advanced auto, they plugged into computer and said is misfiring in the no# 1 cylinder and bank 1 is to rich. so i came home and pulled plug in #1, and sure enough the #1 was fouled out. so i put a new motorcraft plug and drove it down the road, at first it seemed like it was fixed. then it started doing it again ( after about 15 miles). so then i came back home and pulled the #1 and it was fouled out. so i cleaned plug and put the plug in the wire without putting it in the engine. started it up to see if i was getting fire and sure enough it was getting fire. so then i put my compression tester on it and it shows about 115 to 120psi. could that mean i have a bad injector on the #1? truck has about 236,000 miles on it.

 

I'd suspect a bad wire or bad coil pack first. You can troubleshoot this by swap.

 

i thought it was suppose to be a very bad thing if your cel flashes.

 

CEL flash only means misfire...

First mistake is thinking lightly and ONLY CHANGIN' 1 PLUG....

One bad, all are on the way out...

You could have a bad injector... Only way to find out is like GLC said, swap the #1 for the #2. Drive for a while and if #2 fouls with the #1 injector, BINGO!

You are a high mileage example, what is the amount of miles on the plugs and wires? Your wires are likely shot as well.

Let us know!

 

first off let me say thanks for your quick repls. the plugs are about 8 month old ( mtorcraft platinoms AGSF -32FM). i pulled all they other plugs and they looked like the day i put them in. these plugs have maybe 4,000 miles on them. wires are about a year and a half old, truck was acting up so thats why i change just the plugs 8 months ago. one thing i forgot to mention is while i drive the truck down the road. its backfiring through throttle body alot. i also did the lighting bolt test last night, waited till very dark and open hood to see if i could see any arcing going on. nothing and no tic,tic,tic. so it kinda makes me think injector. i have a pic of the plug i just took out earlier today and you can see where its been trying to fire while driving. if someone can tell me where to upload it. or if it even matters. so any help is greatly appreciative.

 

Well, not to rain on your parade, but, you can also have arcing in the plug wells...

BUT the backfiring sounds as if there is a either wrong wiring or a wrong timing... you could just have a sensor bad.

You will have to (like stated before) swap out the #1 injector for the #2 injector and see if in fact that the #2 plug will foul out. This will rule out the injector flaws if any...

Just make sure while you are swapping out the injectors, the battery (neg and pos) cables are disconnected (at least 15 min). This will reset the PCM and when the troubles happen again, go get the code read. That will definitely tell you the culprit...

Good Luck!

 

its funny that you say that, when i had plug out in wire and compression tester on it. while engine was running. i had plug arcing everywhere but where it should be.

 

Well, you might while you are swapping out the injectors, go ahead and change out the ENTIRE wire set... They could have not been changed when plugs were. But REMEMBER, rule of thumb, wires MUST be changed when plugs are.

You can also, take some black tape (temp fix) and wrap the insulator around the plug and see if that will solve your problems for a bit. But, eventually, the arc will burn through the black tape even.

Trust me, I have been there with too many of these engines. It will still be a good idea to swap the injectors though, just in case.

Be sure to use dielectric grease when reinstalling all of your new OR old parts as well.

 

thanks, KIETHHATTER. will give it a try tomorrow. that should let me know whats going on. will post back results after i do this.

 

Yea, you need a motor dude - Those numbers are to low.. You should be in the 150 - 170 range on compression.

Also when you do a compression test, you need to test more than one cylinder - all 8 should be tested for comparison/variance.

Your done @ 115/120 IMO. - Start looking for a motor man - You got some good miles out of her tho.

 

Dangg!!! If you didn't nail it !

It is in this case.

BTW - lazerblade - Don't totally go by what I posted - Check this all out yourself.

I'll post the Data , or Instructions if you need them.. I have a chart somewhere w/numbers and explanations. I know all that stuff is on the Service DVD (Ford).

 

Before condemning that compression reading, check all 8 cylinders. It's only a problem if one or more cylinders are more than maybe 10 to 20% less than the average. You *should* be okay if they are all in the 105 to 130 range.

If you have a low cylinder, shoot a teaspoon of oil into it and test again - if the reading comes up you have bad rings in that cylinder, if not, you have bad valves.

 

My 03' was doing the same thing and got the same reading "misfire on cylinder #1 reading"............replaced to coil pack to plug and spark plug and fixed the problem.

 

compression test thats what i got for all 8 cyl. i know its getting old but just can't afford a new engine right now. yeah they old girl burns a little oil too. but anyways, i tried what KIETHHATTER said and put black tape around they insulator of plug #1. put the plug wire on. removed pos. and neg. off battery for 15 minutes to reset PCM. then hook the battery back up. started her up and took it for a drive, (about 40 miles). no light came on and truck had all its power back. (well for one that has 236,000 miles on it, that is). so when i came back home i pulled #1 plug back out. there was no black sort like before, it was nice pretty white plug. so from what i have learned from you guys. its got to be the plug wire?

 

Just an idea, had the same issue one time. Ended up, I had ended up feeling a little too good when I changed my plugs and wires and had got two of them switched out. Check a wiring diagram if applicable and make sure you have the right wires to the right plugs. Took me 16 months, 5 trips to the dealer and a lot of pulled out hair to find the issue.