Hi all. I have a 2000 f150 4.2 4X4 reg cab with 53600 miles. Coming home today with no warning my truck starts pecking and missing. What could have happened. Normal oil pressure, no over heat on the guage, NOTHING out of the ordianry. Can someone please give me some insight into what might have happened. I pulled the drivers side valve cover looking for a loose rocker arm and all are tight. Any help or direction would be greatly appreciated. Thanks.

 

Some things that come to mind:

a) loose or bad spark plug wire (I have had this happen)
b) fuel delivery (fuel filter maybe?)
c) vacuum leak

there are others but these seem likely candidates and are fairly easy to check/replace.

Does it occur at all engine speeds (rpms)?
At idle?
Heavy acceleration?
All gears? (manual or auto transmission?)

Keep us posted.

 

Sorry for the lack of info. All engine speeds, all gears, Manual tranny. I did have a thought. If the computer for some reason thought the engine was overheating would it go into the overheat failure mode where it pumps 3 cyls not firing them? If that was the case would it return to normal on it's own or would I have to clear the codes? Also would that cause a peck? Please let me know what you think. Thanks,

 

Start with some basic tasks; look for a loose plug wire,broken plug, or vacuum leak like Brian suggested.Then try replacing your fuel filter.Try unplugging the MAF sensor; if it runs better then you know its bad.Cracked coil,maybe? DPFE sensor? Good luck and keep us posted!

 

It does sound like you have to start with the basics and go from there.
Fuel / air / ignition

All applied in the proper time gives a smooth running engine.
There are MANY things on todays engines that can get out of whack. Unless you have a code, or some obvious symptom to direct yo to the immediate cause, start at the basics and go from there.

Plug wires / plugs
fuel filter
vacuum line off/leaking
Do you have any loose hardware on the INTAKE side (where the air filter is located) sucking air throug a loose fitting, etc. that can throw things way out of whack.

the list goes on.

I do believe fail safe mode will reset when you turn the truck off. I have never been in a vehicle in fail safe mode so I don't speak from experience.

Does you CEL light come on when you start the truck?
(Want to make sure the bulb is not burned out) I'd expect a code from what you are describing.

OBTW, what do you refer to when you say "pecking" ?
Thanks.

 

I checked everything this morning. Went to Auto Zone and rented a code reader. It told me mis-fire on cyl 2-3-4-5. I have narrowed it down to all the cylinders on the passenger side. If I start it and let it run a few minutes the drivers side exhaust will get hot. The passenger will still be cold. I have pulled the plug wires at the plugs and at the coil. Fire everywhere. But no change to enging when i pull the wires. The pecking sounds like a lifter not building up. I've been a shade tree mechanic for more years than i care to think about. But i haven't had to work on this one or one this new yet. I think the pecking is either coming from the passenger valve cover or the timing cover. Is there any chance this engine has two cams and maybe the drive for one of them has broken? Thanks for all the help. Any more suggestions will be appreciated.Thanks,

 

Well, guess what. I have a valve spring either collapsed or broken. I'm not sure which yet. Pulled the passenger side valve cover and there it was. Second valve back just flops up and down. Now a couple more questions. We used to pressurize the cylinders with air to change valve seals and springs without removing the head. Can this be done on this engine? Second, is this an interference head? With the valve being loose what potiential do you think there is for piston damage? Someone was looking out for me as the keeper never came off so it never actually "dropped" the valve. Just sitting there rattling around. Thanks for all the information and help. I usually don't answer many posts here because i don't know a lot about this engine. I've had the truck since 7-01 and this is the first problem I've had with it. It's pulled my Bass Boat all over East Tn with no problems. The 4.2 gets a lot of bad press but i can't complain even now. Thanks for all the help. I appreciate it.

 

Wow,are you ever lucky! If that valve had dropped......
Yes,you can use compressed air to keep the valve in position to remove/replace the keepers.Good luck and keep us posted!

 

Thanks for the update.
Glad you found it and glad it was nothing worse.
Let us know the final outcome, and you should post more often!

 

Did you get it fixed? Mine did the same thing about 2 months ago. I used nylon rope. I put the cylinder on bdc, filled the cylinder with rope, and barred the engine over in order to compress the rope up against the valves. Worked like a charm. I have been away from the computer the second I read your post I knew exactly what had happened. My truck is also a 2000, they must have had a bad batch of valve springs.

 

Hi all. Got the valve spring replaced today. didn't have any real trouble. My son-in-law actually done the spring replace. I just got everything ready. He's a lot yonger and smaller than I am LOL. Started right up with no peck...but a miss. I though I may have bent the valve but I checked the compression and it's around 135lbs. What should the compression be on this engine? Torqued the rocker arm down to 29 ft lbs. I'm putting a new set of plugs in tomorrow. Any ideas on what else I should look for? I've looked at the boards and have some of the ideas in my head but I noticed fplorer had this same thing happen. Did you see a miss after the repair? Thanks for all the help. I'll keep ya posted on what I find.

 

No it started up and ran fine, but I did change the plugs when I fixed the spring.

 

Hi all it's FIXED WOOOO HOOOO!! Got home this afternoon and went to AutoZone and they didn't have a full set of plugs so I got one and started changing. Found one bad but not on the cylinder that had the valve problem. Don't make sense but it's not missing now. If there is ever anything comes across I can help with I will. Problem is most of what i know is about the 302 and 351W. I'm old bald and kinda round. But my wife, grandkids and dog love me!!! Thanks to all for the help.

 

What is it they say?
You 'da man?

Great news! glad you fixed.
Round, old, bald people are always welcome here.