I had to unplug my battery and now my '97 4.6 won't idle. When you come to a stop, more times than not it will die. I turned on my lights when I unhooked my battery to make sure everything was drained, and when I hooked it back up, I let it idle about 5 minutes then turned it off. Anyone got any ideas? I can drive it, but it's pretty unsafe.

 

Sounds like your IAC valve is dirty. Better to relpace it. Clean it and it will gunk up again soon. It's the cyndrilical valve on top of your TB. Unclip connection, unbolt the two retaining bolts, bolt on new one, rehook up connection. 10 minutes tops.

I had to do mine a few months ago. With a 6 y/o truck it's about time for it to fail.

John

 

Just another thought.

Was the truck pinging before you reset the PCM ?

If so, you could have plugged EGR ports ?? ( big swag, not enough info to verify ).

Others noticed this, but it tossed a P0401 code in addition to the idle problem.

If you do not have a code reporting ( or don't drive over 48 mph ) then this is a wrong direction.

Just a thought, seeing you havea 4.6, there is no note of cleaning the EGR ports at any time, and at the ae your truck is at, it might have this problem. Then again maybe not.

Some reading on this.
https://www.f150online.com/forums/sh...hreadid=102422
https://www.f150online.com/forums/sh...threadid=99375
There is another thread in the engine section I think with the title of " pinging 4.6 owners read this" or something like that. It shows the EGR locations, and what a crapped up EGR port ooks like.

Just another swag on what might be up.

 

I had a 97 with the 4.6 and it did the same thing. I disconnected the battery for about 30 minutes and when I put it all back together it wouldn't idle at all. Everytime I pulled up to a stop it stalled. I finally started it, and began driving to the stealership to report the problem and pay to have it fixed. In the 20 minutes it took to drive there, it quit doing it and returned to normal. I asked the service manager about it when I arrived. He said sometimes the computer needs a few cycles of accelerating and stopping before it re-learns the proper idle and run settings. Didn't sound too good to me, but it never did it again. I never disconnected the battery again either.

 

You're right, that does sound like BS.
Every time I do a mod, I reset the PCM, and mine does not die on me ( 5.4L ). I think that would have been posted as normal, with al the moding going on around here by now if it were correct.

 

Mine does that occasionally when resetting the computer! it's just re-learning the idle point ..i don't think it's a big deal!! no i don't have plugged ports..but i do run a ported upper elbow larger T/B and larger air intake .....

 

got it fixed...replaced my IAC and it purrs like a kitten. I guess my ECU adapted to my old IAC, but the reset thru it out of whack. I appreciate all the help.