Hey all,

1997 F250 light duty *the oddball* with the 5.4 Triton. 195K miles

Guy I'd bought from replaced spark plugs, I went to start it a couple months ago, as it started, I let off the key, and I'm pretty sure it backfired, and blew a COP assembly off a plug! Hole wasn't stripped, plug not out, so I figured the kid forgot that 1 bolt that holds the COP down. Replaced, no problems..

Well, it did it again. All the COPS are down and tight, but I have to hold the pedal down for it to actually start running, and it won't idle without my fluttering the pedal. I'm pretty sure it's backfiring here and there as i mess with the pedal, but it's not a constant backfire, just random as I hit the pedal and back off so it isn't spinning 3000 rpms.

It has a couple codes for 02 sensors, but nothing else.

Its a 2nd vehicle, so I want to do this as easy on the pocket book as I can, since it's right before Christmas, but I want it right, I don't appreciate being stranded lol

Is there anything I can do to test anything? Or do I just buy a new COP and plug it on each cylinder at a time to try to fix it? Is there any other ignition system piece to check?
Could it have jumped time???

I have been a GM guy, old work trucks were Fords, and I was impressed with the beating they took... so I nabbed this one, and right now I'm looking like a fool for it lol I know nothing of ford motors, any help is really appreciated!!

 

Vacuum line on the back of the intake came loose, must have backfired it off.

is running again, thanks anyways

 

I have no idea about the cause, was thinking maybe IAC, but glad to hear you got it.

 

make sure the ALL spark plugs are torqued to 28ftlbs....this will eliminate issue with spark plug ejection . not saying that has happened, just good to make sure it is done right.

what codes came up for the O2 sensors??

double check the elbow make sure that it is not cracked, it is a know area of concern...or other vacuum leaks should generate p0171 or p0174 codes. make sure you reset or clear the codes & recheck to see if any additional codes pop up.

Agreed^^^ rough Idle is hinting towards the IAC as being dirty or faulty....best way to clean this it to remove the whole throttle body housing...then remove the IAC, there is a small plunger/pintel inside the IAC that gets carbond up & sticky, clean with WD40 making sure the plunger is freely moving...clean everything else with carb cleaner on the inside of the throttle body and reinstall...just part of regular maintenance.

could not hurt to clean the MAF sensor too...make sure that your cleaner is safe for MAF sensors and replace that ole PCV valve... relatively cheap things to do that your truck will be happier for.

 

Uh, guys... He already fixed it, it was a large vacuum leak caused by a loose hose connection (probably the PCV hose).

 

Yea, now that it's waaaay past the point lol I completely forgot about posting that here.

The pcv line that runs to the back of the intake is where the failure occured, and under that cover (which I managed to snap off and about rode to the ground lol), I forgot about it.

As for the codes, right now I don't have them saved in the program, but they were both evap, and now that it's been cold, aren't even coming up. I imagine just old vacuum lines is all that is, there are a couple in the top of the motor that are real trashy looking, that will be changed once it warms up.

I didn't know the pcv valve ever needed changed, I'll buy one and toss it in, thanks for the tip of that! I haven't taken it apart and cleaned everything out either, it's running, so I figure i'll wait til it gets a bit warmer. I'll take some pics of how nasty everything looks lol