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Jan 31, 2016 | 02:37 PM

rbr658

Thread Starter

5th Wheeling

Joined: Jul 2013

Posts: 47

Likes: 0

What's going on here

I have recently had around $1500 of work done on my 94 F 150 5.8L. Tune up, injector service, PCV and idle control valves, oxygen sensor, etc. (tune up components also). Still idles rough but smooths out when up to speed but on occasion will stall at a stop. Has 177K OM and had stuff done that had probably never been done in 21 yrs. With the idle the way it is I have had the truck stay in second and then will surge and slam into higher gears (this is intermittent). Mechanic is kind of stumped with diagnosis. I would appreciate some thoughts on this please.

Jan 31, 2016 | 02:54 PM

khadma

Carpenter Local 745

Joined: Apr 2006

Posts: 5,794

Likes: 11

From: on da beach

Look/listen for an upper air intake leak or take it to a shop that can do a smoke test for you.

Jan 31, 2016 | 03:41 PM

subford

Fleet Owner

Joined: Aug 2005

Posts: 23,667

Likes: 301

From: Easton,Ks

You need to get the self-test ran and see what it says in KOEO & CM.
But sounds like an EGR valve sticking open and maybe a bad VSS input to the PCM Computer.

Jan 31, 2016 | 05:21 PM

valkyrie9901

5th Wheeling

Joined: May 2014

Posts: 44

Likes: 4

Coffee can vacuum got a rust hole in it?

Jan 31, 2016 | 05:59 PM

rbohm

Senior User

Joined: Oct 2002

Posts: 326

Likes: 0

From: tucson/luray usa

i agree with the others, a vacuum leak is the first thing i would suspect. and it can come from a variety of sources, from intake gaskets leaking to vacuum hoses failing, etc.

the other thing i would look at with modern vehicles especially is electrical connections, and grounds, grounds, grounds. these can also cause similar systems issues.