2002 4.6 4WD Engine shut-off during Idle

[Mrjonathon]

Hey Guys,

I've had this expy for about 2 months. i don't know any of it's maintenance or issue history.

Twice in the past week, I've been at idle and the engine shuts down. Almost like an manual transmission if you were to let go of the clutch.

First time i was in the left turn lane, engine may not have been warmed up yet, I had only been on the road for maybe 3 miles, around 7-10 minutes. The second time at a red light and engine was not yet warmed up, died at the first traffic light. Both times i shifted back into park and turned the truck back on. It started like normal both times.

The idle has been vibrating rough ever since I got the truck. Vibrations lessen when in neutral instead of drive.

Any help would be appreciated. May even be multiple issues. It has 238,000 miles.

 

[1997SCEBFEX]

sounds like your idle air control valve (IAC) is a place to start.
4.6 or 5.4L?
on my 5.4, it's on the rear side of your intake manifold in front on the firewall. easy to replace and not very expensive, or spray with brake cleaner a few times, shake it out, reinstall.

other things I'd look at:
Throttle position sensor
Fuel and air filters
MAF being dirty/occluded
any codes (CELs) been pulled to see what's in the computer?

sure others will chime in.

 

[Mrjonathon]

sounds like your idle air control valve (IAC) is a place to start.
4.6 or 5.4L?
on my 5.4, it's on the rear side of your intake manifold in front on the firewall. easy to replace and not very expensive, or spray with brake cleaner a few times, shake it out, reinstall.

other things I'd look at:
Throttle position sensor
Fuel and air filters
MAF being dirty/occluded
any codes (CELs) been pulled to see what's in the computer?

sure others will chime in.

Thanks for the reply. I’ll take a look at those this weekend. I’m thinking of trying a Seafoam treatment. Might clean up a few of those areas.

 

[Mrjonathon]

Well whomever owned the truck before I bought it disabled the CEL.

Turns out there were a couple of reasons for a CEL to be on, I just didn’t know it.

On of the reasons was a P0401 so today I took off and cleaned the EGR, IAC, Throttle Body and Throttle Body Manifold. The PVC hose had a cut through half of it. I’ll be able to get the new PVC hose tomorrow.

Hopefully that will clear up the rough idle and the stalling!

Thanks for your ideas to look at!

 

[Adieu]

Rough idle can be a misfire, any p020# or p030# codes?