Hello guys, I've been after a gremlin for too long now. What could cause rough idling at a stop on my 2007 XLT 5.4 3v if I replaced the following already: Spark plugs (motorcraft twice) coil packs (twice) all connectors pigtails, timing kit, cam phasers with lockouts, injectors, intake manifold, fuel filter, camshaft position sensor, knock sensors, oil pump, cleaned MAF and TB, oil filter (motorcraft), battery, air filter, oil pressure switch and on top of this a complete engine rebuild, new cams, lifters, etc. It runs good, no hesitation or misfiring while driving but when I stop it idles rough. My mechanic ran out of ideas and can't figure out whats wrong and I'm done throwing parts and don't get any results. this truck is driving me nuts. Thanks in advance

 

Whats the idle RPM

 

500/600 steady, needle doesn't move at all

 

Geez, you forgot the kitchen sink. Mine doesn't idle so great and I've given up on it and haven't put nearly as much major stuff as you have. Plugs, coils, injectors, filters, fuel pump, fuel module, alternator, 02 sensors, exhaust with new cats, vct selonoids, and on and on. Speaking of, and excuse my ignorance but are the vct selonoids part of that engine overhaul? I think they can cause a rough idle but then again so can a lot of other things. Sorry I couldn't help

 

Good question about the VCT solenoids, the thing is that when you do the cam phaser lockouts it disables the VCT solenoids so they're not an issue, I asked the exact same question

 

Gotcha. That whole system confuses the heck out of me. Man, I just want to do regular maintenance stuff and drive my truck but my God the new technology is just mind bogling. My mechanic said its only getting worse. Anyway, good luck

 

What are the chances that the "rough" idling its caused by timing being a little off? Just almost imperceptible

 

Check the condition of the FPDM. It's possible it's at the end of it's life and causing these issues.

 

Wouldn't it throw any codes? Or cause more issues?

 

I'm not sure about the codes. Is there a dedicated OBDII code for the FPDM, or would it show up as an intermittent misfire?

I had the same issues with my 06 and replacing it solved my issues. It may not be your solution but it may warrant a quick peek, just to eliminate it as the cause.

Fingers crossed you find it! I know how frustrating this can be