Hello all, and Merry Christmas!!! Hey on my 351 W, which is the 5.8l., I just replaced my idle air control valve. Does the engine and computer need to reset or adjust to this new IAC? The van is running rough and a couple of little backfires here and there.. It Idles great, as soon as you put in in gear it runs rough. I drove it around town for 25 miles, it never stalled but when you get to stopsigns it seems likes it wants to, but does'nt..Thats all I can figure out, is the PCM or computer needs to reset. This is a E250, 1995.. Thanks

 

If you wanted to reset the computer, I believe you just need to disconnect the battery for 15 minutes or so and then reconnect.

I don't think that's your problem though. There are a few other things that I feel should be checked out first. I'd make sure that you don't have a loose or cracked vacuum line causing air to slip past the IAC valve. Next, I would check the TPS. I had a throttle position sensor go bad on my old truck and it exhibited the same problems you are describing. I replaced my IAC valve thinking that was the problem, but it turned out to be the TPS.

Good luck!

 

There is no "relearn" on the IAC, although PCM controls the IAC. Like Dave said, check vacuum hoses / electrical connections.

Did you try to pull any codes? Did you run any testing procedures?

 

I did the TPS last year. I also think at this time I might need a CAT. I have to go for aims test here in ohio, so that will tell me my problem. I'll do the battery thing this weekend and then go from there.... thanks.

 

Let us know what you find out in case we have to deal with it next!

 

I just had my 93 Econoline acting the same way the week before christmas.
I have the 351W also, it ended up being the MAP sensor and the o2 sensor.
Not sure if the 95's have a MAP or MAF sensor.
But pull codes if you can first before throwing more cash at it.

 

I've got a 95 f250 5.8 gas with a low voltage at tps...i get a code 122 tps low voltage and a code 327 ...and a 998 with the engine running. under 1 volt tested at tps , ohm meters says tps is fine but i get no current to tps

 

Did you check for a solid ground?

 

It does sound like you are getting too much unmeasured air into the engine.

On the front of the throttle body, down low, there is a 135 degree elbow that goes out front then turns back towards the passenger side. Often is it cracked and can cause the engine to stumble when coming to a stop.

 

Ok guys, I have it all figured out. Somehow in the heat of things a wire came off of the distributer. So it was a loose wire... This whole time checking this and that, so I went ahead and changed all the wires, because I found another loose one.. Thanks for all your inputs..... Happy New Year.....

 

My father used to say "it is the obvious and simplest cause in 95% of the time".

 

Your exactly right. I need to check and then double check. If it was ok before, why is it running so bad now? My Dad taught me to work on cars, I have seven brother and sisters. At one time in our lives we had nine cars in the "yards" around us. I'll never forget that day when he said "you got all of this now, right?" because this is the last time i'm doing it. "Mark my words". So that's why I enjoy doing it, but I think i'm going to be done with that soon too.

 

Don't feel too bad - we all do it at one time or another. I didn't get a coil pack plugged back in tight enough this summer and it worked loose on the freeway while I was towing the camper. You wouldn't think that losing one out of 10 would make that much difference, but it did. I helped a friend put new head gaskets on his Merc years ago and we couldn't get it to fire. We chased our tails for 2 weeks before I realized that we neglected to reconnect the power to the computer....