allanmcc

I have 2007 Lariat with the 5.4 (98,000 miles) and I've had a misfire problem for a while now. I have poured over these threads looking for ways to address the problem.

Problem: A little bit of a rough idle, misfire between 1st and 2nd gear, a violent misfire in fourth gear while cruising (40-50mph) and trying to accelerate without accelerating enough to cause the transmission to downshift. Also, I am NOT getting a CEL so no codes are being generated.

Here is what I have done to address the problem:

(1) Replaced all plugs and coils (using motorcraft). Only broke one plug!
(2) Replaced the VCT Solenoids (this cured my engine click sound).
(3) Cleaned MAF sensor.
(4) Replaced fuel filter.
(5) Cleaned the fuel injectors.
(6) Obviously, changed the oil a few times.

I am really trying not to pour money into this truck and doing all of the work myself. I am not against taking it in but I am afraid I'll just get told to replace the engine or something.

Any thoughts out there.

Thanks,

allanmcc

joe mcmillan

Have you checked your FPDM (fuel pump drive module)? If not, take a look to see if it is completely intact.
DTC's are generally the result of the CEL coming on, though some DTC's are stored in the PCM/ECM without kicking a CEL.
If you have a tuner, you can look for DTC's that may be logged even tho the CEL has not showed up.
If you don't have a tuner, a local parts store can help you.
Also take a look at the throttle body. It may need cleaning but not likely causing all of your issues.

techrep

iTrader: (1)

How do you know its a mis-fire ? CEL flash ? fuel filter ? FPDM ? how were the injectors cleaned ? what brand COP's were installed ? new Boots and springs ? Dielectric grease applied ? Cat's Clogged ?

allanmcc

Haven't checked the FPDM. Will do that.

As far as coils, I dropped the money on brand new motorcraft coils with new boots and springs. Applied dielectric grease. Injectors were just cleaned with Chevron fuel injector cleaner in my tank (nothin in depth like removing them which maybe is not sufficient.)

Not sure about the cats. I check into that as well.

Thanks for the tips.

nrivera04

My misfire was the result of a cam follower on an intake valve in cyl#3 locking up. Scored the cam and was not allowing the valve to fully open. I'd recommend troubleshooting the fuel system first, but you may have to pull a valve cover and look deeper if you can't find the issue.

Fx4Mark

My Misfire was a burnt valve sometimes the engine light would come on and sometimes not for a month. My truck shook like a washing machine that wasn't balanced at idle. Once i started to drive, it wasn't that noticeable but when i hit about 50mph the truck would shutter until i either lifted my foot off the gas or accelerated. A leak down test or a compression test, will get you pretty quick results if it's a valve problem.

allanmcc

Fx4Mark, what you describe sounds exactly like my truck. If it is a burnt valve, are we looking at an pretty expensive fix? Honestly, I'm trying to figure out if its worth more money to diagnose and then fix or if it is time to just part ways.

Fx4Mark

If it is a burnt valve you are looking at some money! I'm at about $2000 at this point, but i decided that while it's apart, it would be a good time to do exaust manifolds, phasers, timing chains, guides, tensions. My local machine shop did the head that was $450 each. i did both. And it is many many many hours of tearing it apart. I took my time cause i didn't want anymore expense. If you need to pull one of the heads you have to replace the head gasket, head bolts, front timing cover gasket the valve cover gasket the intake manifold gasket the crossover gasket and i believe more. Things add up quick. But after doing this it's not that bad. Don't get me wrong it's a lot of work but if you love your truck as i do it will be worth it in the end.

Eric0508

Im gonna throw out there a suggestion to do a transmission filter and fluid change. Probably not the cause of the rough idle, but dirty fluid could cause your other 2 symptoms and is inexpensive and good preventative maintenance.


This is a common problem in other Ford transmissions so I wouldn't rule it out.


the other question I have is did you replace your plug boots when you did your plugs?