I have a 2001 Ranger 4X4 4.0L V6 auto trans that will stall sometimes when I shift it to park. When I shift it to park the rpm seems to drop and most of the time it stalls. When in drive and stopped the rpm's stay up and it's fine. I've recently changed the fuel filter and dpfe sensor and had the local dealer change the plugs after the problem started to happen although I don't trust them. I've also added a bottle of fuel injector cleaner. On other posts people point to the IAC valve but wouldn't I have trouble other than while in park?

Thanks for any help,

Bill

 

Have you had the computer scanned for trouble codes????

Most autoparts stores will do it at no cost, if your having problems & there may be "pending" codes set, even if there is no trouble light.

Maybe it'll have a pending code stored that would offer up a good clue on where to begin your troubleshoot.

 

I would add that if the IAC is dirty, it will be slow to respond to commands from the ECM.

I had a problem with my car doing the same thing. I found that the alternator regulator was cooked. No idea why this affected the idle, but there were exploded transistors inside the regulator. Put in an aftermarket and all has been well since...

I would clean the IAC, and after checking for codes, disconnect the battery and clear the ECM memory. Reconnect, and let it re-learn its idle information.
tom

 

I'll bet that it is the IAC, my 01 did the same thing but would never fully stall. I cleaned the IAC, as best as I could, but replacing it did the trick.

 

Thanks, I'll take a good look at the IAC and check the codes. Tom, what made you even look at the transistors and was your battery going dead?

Thanks again,

Bill

 

Battery was *not* going dead. I think I checked the charging volts and they didn't come out as expected. Probably after hearing something on a radio show. I think I tested the regulator and alternator using the shop manual and reading voltages and they were off. Drilled the rivets on the cover and bits of blown up black transistor body fell out. I think my brother helped me clean the engine at a car wash.... with a soapy spray. Not a good idea to get H2O and soap suds in there..
tom

 

Will be interesting to hear if the computer has set any pending codes.

The IAC is a good suspect imo, but as it seems to be behaving ok in "D", it wants to make me suspect a couple of other things too, like maybe a acting out "neutral/park" switch on the tranny.

Does the idle misbehave in any other position???? Will it misbehave in "N"????

Will it misbehave if you stop at "R", on the way to "P"????

Are you having any other engine or tranny driveability problems????

 

check your fuel pressure regulator. it may be letting way to much pressure through. my dads truck would do this in neutral till we tested the regulator

Matt