me again guys, i got the code this morning, misfire on #3, brought it in this afternoon they say gotta do more testing, the coil supposedly is good and plug. they don't know the cause of it. what else could be the cause of the code? been chasing this problem for a month now. help!!

 

Could you provide me with a bit more info as what they have done already?

and just a guess here but I assume we're talking about the truck in your sig

 

Are they working on the correct plug. #3 is the 3rd back on the passenger side.

 

i guess i left out some info in this post, yes it's the truck in my sig. i was so frustrated already. they said they "checked" the coil and it was fine. they checked for vacuum leaks, didn't find anything the first day told me bring it back the next day because they have to take off intake to get to the back hoses, i couldn't believe it. the thing is, here, i don't have much choices on where to take it for repairs. the dealership here is a complete joke! they are incompitent, lazy, and just don't care about what kind of service they give. so anyway back to the truck, today they changed the #3 plug, and they tested it and siad it runs good again. i picked it up, started it up and she ran nice and smooth again. i was stoked. drove it about 2 mins back to my shop, let it idle a bit and it started rocking again, rough idle was back. i called them and said it was back he tells me ok bring it back tomorrow, he'll change the coil! i asked him yesterday why they didn't just change out the coil, he said to save some money, try the plug first.the trucks been there 3 days in a row.tomorrow if they change the coil and it's not fixed i think i'll just snap! sorry for the long post just have to let out steam i guess thanks for the replies guys.

 

Did the new coil take care of your problem? I am having a misfire on #3 as well and I think that is my problem too.

 

well, my problem wasn't the coil, it was the injectors being clogged with white powder residue. still not sure what it is, but at least i know the fix. i ran seafoam through brake booster and tank a day before it happened, i didn't put anything else in the truck. hope you find your fix.

 

did you replace the injector?
If so how much were they and how hard was it to do.

 

It's the gas being used. Already know of this problem here. There has been a law suit over it in the southern states.
Run fuel system cleaner and change gas brands.

 

really? it is the gas then? i thought it might be some bad gas, but i always use chevron gas. after the truck started running bad, i did fill up with shell, thinking it might be the gas. i changed the fuel filter, and the gas in it came out a little white. i'm going to drop and clean out the tank, and pull all the injectors and have them cleaned and then i think i'll switch to shell gas, so much for chevron with techron then huh? lol too bad i can't have them pay for the cleaning of my fuel system. what a pain.

 

Kauaid;

Just in case you still have the problem with #3 misfire, here is one more thing to check out. I had the same problem and the mechanic I use (very competent) had trouble diagnosing it. Finally one of my vacuum hoses popped off and he figured it out. I had over 4 lbs of backpressure from the exhaust - cause; plugged cat. Hope that helps.

Nate

 

hi guys i have a 2000 svt and i have had a miss fire in #3 and running lean in the 3rd bank my truck studders when i get to 40-45mph and then goes away the engine light never goes off i have had the plug replaced coil package and the injectors replaced too. the guys i have working on my truck are good the owner himself has an svt so i trust them but they cant figure out exactly what the problem is PLEASE HElP this is annoying as hell thank you........

 

I am not sure if this will help any one but it is worth a try.

This is quoted directly from the service log and bill.

"Customer states engine has a mis fire under load - slight hill (up hill is worse)
Check for codes no codes found. Performed fuel pump and injector test, also stress test on all 8 coils. Found #6, 2, 3 coils weak. 2 and 3 has water. (no idea what that means) Also check mode 6 fore fires. One misfire was recorded in memory. Replaces 3 coils and 3 spark plugs. Checked for codes again. Road test vehicle. Running good now."

https://www.f150online.com/forums/sh...d.php?t=205844 is my original post and it kinda explains the problems I was having.

Here are my questions.

What is a Stress Test? It was dont on the coild to see if they were gtg?
What does 'has water' mean?

This repair cost me a $100 deductable and over all cost ~$600. I know it is alot but the coils alone were 120 they said LOL. Not my money

~k_day64

 

hey guys, my truck is fixed, running good again, finally. it was the injectors clogged with some crap. i dropped fuel tank and it had lots of clumps of crap in there, some a**hole dropped stuff in my tank! i put a locking gas cap now. i should get a rotty next to put in the back of the truck to keep d**ks away.

 

Let me add here that you just showed a condition that many fall into that can't find the problem.
What happens is the PCM is so good at detecting a cylinder that is down a little bit on power from poor injector operation that it will set a code and a possible CEL lamp and not respond to a plug and coil change because that is not what the fault is.
The PCM actually measures time of rotation for each cylinder and compares it to what is stored in memory for the average for that engine.
Any deviation to far from the reference is considered a fault for whatever reason so it's not alway a plug or a coil.