Engine issues

[JohnH55]

So I drove my 2001 explorer sport 4.0 SOHC through 3-4 inches of water at 35 mph. I regret this now... Right after I noticed my truck would not shift past 2. So I pulled off and restarted the truck, it instantly reved to 3k without me touching the gas. I turned it off and let it sit then tried again, it worked like normal and I made it home. The next day it would not start, so I looked at the air filter and it was damp, some water had made it into the air box. I cleaned the map and it started and drove fine. But sometimes when I start it, the idle hits 3k. Should I replace the MAP, and TPS? When it runs normally it sounds great, (so no internal engine damage).

 

[rasouth]

I would think that if it runs fine some of the time that the problem may not be the MAP or TPS, but I could be wrong. (I have a '96 4.0 OHV so there is a little difference between them.) Have you tried running it without air filter? I have driven mine through mud, water, streams, flooded streets... with no problems.

 

[410Fortune]

MAS
Mass Air Flow sensor
Likely got some debris on it, try cleaning the mas sensor

Next up would be to checkout your IAC, the idle air control sensor.........this is the only sensor on the engine that can cause it to rev that high without touching the throttle pedal, if the IAC valve is sticking you will get strange RPM's

Also look for any vacuum lines, intake hoses that may have come loose

 

[JohnH55]

MAS
Mass Air Flow sensor
Likely got some debris on it, try cleaning the mas sensor

Next up would be to checkout your IAC, the idle air control sensor.........this is the only sensor on the engine that can cause it to rev that high without touching the throttle pedal, if the IAC valve is sticking you will get strange RPM's

Also look for any vacuum lines, intake hoses that may have come loose

Can the IAC valve have intermediate failure? I ask because sometimes the truck starts and runs normal with no high Rev.