About ready to roll it off a cliff!

[Chuck29414]

Very frustrated with the ongoing issues with my 2007 XLT 2wd 4.0 w/111k miles. It has a rough idle on start up that clears away pretty quickly when given some throttle. Here's what's been recently done to it: New plugs, wires, and coil. New EGR valve. MAF sensor cleaned. Throttle body cleaned. All of the harness clips to the MAF, Throttle body, and EGR had exposed wiring. I replaced all of those from a junkyard donor and properly done with heat shrink butt connectors. Sometimes the idler pulley jumps a lot which makes me think harmonic balancer but it seems tight and belt doesn't squeal. Lots of steam from exhaust when first cranked but it is not losing coolant or running hot. Also kind of hear a very faint popping noise from exhaust when idling rough. After initial rough start up she drives and idles perfectly. Intermittent wrench light but tranny shifts smooth and I recently changed fluid/filter and solenoid pack. Check engine light comes on eventually after clearing for P300. Please help!

 

[donalds]

Sounds like a misfire to me when did you last change your plugs and wire's?

 

[Chuck29414]

Sounds like a misfire to me when did you last change your plugs and wire's?

One week ago. It is misfiring just cant figure out why

 

[CharlieK9]

Have you tried this; the ECU still thinks you have a dirty throttle body and needs to re-learn.

 

[Chuck29414]

Thanks for your reply. Yes, I disconnected the battery and drained the capacitors as suggested off of videos on here. I also let it idle for 20 minutes after reconnecting the battery and starting it up. After that I drove it normally for 20 minutes. Does it take more than that for the computer to relearn?

Have you tried this; the ECU still thinks you have a dirty throttle body and needs to re-learn.

 

[07EddyB]

What I got from your post is that it is running good actually.

Don't get caught up in 100Kitis - where you start worrying about every little thing because it has 100K miles and you are afraid it is just one fire cycle from dying in a spectacular way.
Many members here have taken them far further and continue to do so.

 

[Chuck29414]

No it's not that. It recently started throwing tons of codes for multiple misfires and egr valve as well as transmission codes. That's why all of these parts have been replaced. It's running better but it still misfires on start ups everyday. My wife drives it and we have an infant. I want it to be running perfectly for her.

 

[boominXplorer]

What plugs did you put in it?

 

[Chuck29414]

Thanks for the reply. We used the Motorcraft plugs it calls for. It was having same issues before and after new plugs were installed.

 

[JAWIT]

All of the harness clips to the MAF, Throttle body, and EGR had exposed wiring. I replaced all of those from a junkyard donor and properly done with heat shrink butt connectors.

I'd recheck this area again, just to be certain some of the wires are not touching. Are you sure the wiring you got from the donor vehicle was in good condition? I'd also pull back the black insulator covering on the throttle body just to be sure there aren't other areas that have exposed wiring.

 

[BennyTheButcher]

I have my 06 XLT 4.0L RWD at the shop right now for an almost identical problem...like scary identical. Sounds like the only major difference is that my rough idle doesn't get much better as the vehicle warms up. The engine shakes, idle hunts a bit, and random misfires. I've thrown everything at it just like you (egr valve, throttle body, MAF, re-wired harnesses and electrical everywhere because a lot of insulation was toast, new plugs/wires, coil pack, o2 sensors, cleaned and tested fuel injectors, intake plenum gasket, crankcase sensor, PCV valve, vacuum leak test, fuel injector pressure sensor, fuel filter, canister purge valve). All sensors and LT/ST fuel trims seem to be working perfectly when I run a live test. I finally threw my hands up and sent it to the shop for another set of eyes. I'm hoping they find something, because I have a sinking feeling the timing chain may have jumped a tooth. I've only owned the truck since March (and have just now put 3,000 miles on it), so I don't know much about previous maintenance. However Carfax report makes me think it's still in its original timing chains/guides/tensioners. Fingers crossed it's something simple and stupid. I will definitely keep you posted. I hope this helps.

 

[BennyTheButcher]

Also, related to the crappy, degraded wiring...

Can anybody tell me where to find a PCM pinout diagram? I asked in a previous post but got no replies. Would be nice to check voltage from PCM to components.

 

[Rcflyer330]

Also, related to the crappy, degraded wiring...

Can anybody tell me where to find a PCM pinout diagram? I asked in a previous post but got no replies. Would be nice to check voltage from PCM to components.

Alldata is one of the only places I know of a pinout diagram or a factory service manual.

 

[BennyTheButcher]

Alldata is one of the only places I know of a pinout diagram or a factory service manual.

Thank you very much! I'll check it out

 

[Drewmcg]

Bad catalytic converter(s)? Have shop do a backpressure test on each bank.