Idle issues

[thetequilaworms]

the truck is a 98 Ranger. 2.5L spd.

my problem started a few days back. I was driving home from work and on the way home i noticed that when Id shifts gears I can hear the RPMs staying at whatever I was cruising at. Sometimes they would even climb/surge. This had happened before a few months back, after a few minutes of research i decided to clean out the AIC valve. I tried it again this time and had no luck so i bought a new one thinking it would help. NOTHING! New AIC did nothing. Next I cleaned out the MAF sensor, still nothing.

Now im thinking its a leak somewhere, so I got some brake cleaner and went to town on the hoses, no dice. Next, I think its going to be the TPS, i went and bought one of those and swapped that out. still doing the same thing. WTF!! it still happens..

the RPMs will stay at whatever i was cruising at or they will climb a bit and they dont come down to regular idle until im at a complete stop. the truck runs fine, it doesnt bog or anything.

any ideas you can throw at me, ill give it a shot!! Its my DD and it is becoming a real pain in the ass to drive around like this...

Thanks

 

[PanamaExpat]

Mine does that idle thing from time to time too.... AIC is new and it does the same thing as the original.... Mine also randomly stumbles and dies now and again while idling. My self check shows that it is EGR related most likely the DPFE as I have tested the EGR and it works fine.

 

[thetequilaworms]

at this point ive replaced the AIC valve, the TPS and the DPFE. No dice.

checked the EGR and it works fine.

im getting ready to light this truck on fire haha

 

[RonD]

Check for mechanical issue in the throttle plate and cable.
If you have cruise control check that cable as well
Weak/broken return spring may not close throttle at higher rpm

Also remember to disconnect the battery when replacing sensors or any work on the engine.
This will reset the computer so it can learn any changes.
Many have "fixed' a problem but never knew it until the next time the battery was disconnected.

 

[thetequilaworms]

It's never been touched. The problem started happening intermittently and then just became constant. I was thinking about the throttle cable sticking but then I thought, if I rev the motor while the truck is sitting still the RPMs will drop down to normal. They only seem to stay high when it's moving/under load. As soon as I come to a complete stop, they drop to normal. Very unusual.

 

[PanamaExpat]

Mine does that same thing..... I haven't been able to track it down yet either.

 

[OdinAF]

Does this happen under cruise control? Does it shift fine, this reminds me of a transmission issue with gears slipping lose, causing surge, with the rpms staying the same does it jerk forward when it shifts?.

 

[shane96ranger]

Pretty sure it is a 5 speed and the OP was doing the shifting.

Sure sounds like a MAF to me. I know you just cleaned it, but you may try it again.

Sent from the can

 

[OdinAF]

Try resetting your computer, If you cleaned the MAF and IAC (which only would effect you at idle not driving), your computer needs to recalculate the whole 9 yards.

Also sounds like a MAF or stuck or malfunctioning Throttle Body sensor (which you ruled out) or TB in general (the blade wing thing), Would make sense if your at idle this does not happen, but while driving the air might (unlikey) be creating pressure on the TB keeping it open or pushing it open more creating a surge(loose wings maybe?),try cleaning your TB,MAF and reset your computer and then try.

It doing it under load, do not rule out bad springs etc, it could just be a fluke that it doesn't do it at idle even thou it should. Think inside the box and outside the box. You could have a air leak somewhere bringing unregulated air into the system.