AlleninNM

Hey All,

Have a 2006 F150 5.4 with 200K. I am getting an intermittent rough idle, no matter whether in park or drive. Once I start to drive forward, the miss goes away immediately and does not return as long as I am moving forward. If I put it in park or neutral and run the rpms up, it will run rough, particularly about 1800 rpm. But it runs fine while it is in drive and I am accelerating or holding steady at 1800 rpm. Problem is only at idle or when in neutral/park and running up the rpm. There are no engine codes being thrown. Any thoughts on where to start looking?

Thanks,
Allen

techrep

iTrader: (1)

When was the last tune-up ? Plugs/boots/springs/tb cleaning/Maf cleaning/fuel filter...

AlleninNM

Plugs and COP done about 60K ago. Fuel Filter done 25K ago. MAF cleaned last week. (It looked pretty good) It could be in need of a general tune up.

I have had some vacuum issues, which were addressed. If I was getting rough idle only, I would suspect vacuum leak. Does a vacuum leak make sense if it still misses at 1800 rpm in park/neutral?

BadFish523

Time for new boots and springs or at least clean them if they got 60k on them. People on here are probably tired of hearing it but my last 4 or 5 misfires have all be solved with new or cleaned up boots and springs. Cost is under $40 and it sure seems to work for me. Simply remove the coil, remove the boots and spring from the bottom of the coil. Clean contact point of spring and coil with electrical contact cleaner, put new spring on, dielectric grease on the point where the boot contacts the coil (careful to not get any on the spring or the contact point of the spring and the coil), then very carefully dielectric grease on the bottom end of the boot where it contacts the plug but not on the spring so as to not interrupt the connection between the spring and plug, then carefully put the coil back on the plug and do the relearn process.

AlleninNM

Thanks for the help. I will do the cleaning on the boots/springs and see if that improves things.

BadFish523

At 60k I would check them very closely or just put on all new boots and springs. If they have and cracking, or are dirty then they will probably need replaced.

techrep

iTrader: (1)

With 200 K miles on the truck ... they need replaced do the plugs too.. 60K miles is Fords new recommend interval for replacement now.

BadFish523

Thats right, I forgot it's 60k now. So OP the recommendation is all new motorcraft plugs and all new boots and springs.

AlleninNM

So I picked up a Blue Driver scan tool and it is giving me a pending code for a misfire on cylinder 3. Also checked short term and long term fuel trims on both banks, which was within normal ranges. So I will start with the cleaning/replacing the COP on 3 and see where that gets me. I won't have time to do the full plug and COP replacement for a bit.

redfishtd

Every 60k all new with new plugs . Base line with this engine ,you can't diag without doing this first . only use sp546 or champions . Clean out snout area of plug in cly with carb cleaner to dissolve combustion carbon . That carbon breaks plugs going in or out .