engine trouble

[shadow1]

Have a 4.0l ranger standard. while driving, when i take my foot off the gas and disengage the clutch to shift, my engines rpms shoot up about an extra 500rpm as if i still have my foot on the gas. They eventually fall back down after about 5 seconds.

Also when starting, the truck shoots up to 3000rpm aggressively for some reason.

These problems started happening at the same time. Any ideas? I can provide more info if needed.

 

[Lrpalo]

I have had a similar issue, i was able to temporarily fix it by cleaning out the idle air control valve with some carb cleaner but it has come back

 

[jhammel85]

I'd say it sounds pretty likely that it's the Idle Air Control Valve. It's worth taking off and cleaning out. Hopefully that fixes it.

Any codes in the computer?

 

[shadow1]

took off the trottle body and noticed some oil in the intake, could this affect the IAC? Could my pcv valve be sticking which could be why its sucking oil?

As for codes ill get them asap

 

[jhammel85]

Sounds like you might have some blow by. I would definitely clean it out w/ some Throttle Body Cleaner. Take the IAC apart and clean that as well the best you can with some TB Cleaner.
Wouldn't hurt to remove and clean any other sensors that go into the intake either.

 

[shadow1]

when i unplugged the IAC it idled down to like 700-800, when i plugged er back in she hiked up to like 3k again. Thinking IAC is correct. Can i drive with this unplugged with a hot engine? to see if the rpms still hike mid shift?

Also for the blowback, that would be the pcv valve rite? engines got 250k km on it so its due for a new one.

Im guessing the blow by could have buggered up that IAC real good

 

[feellnfroggy]

Idle Air control valve is exactly that, without it it will idle rough when cold. Id rather run the high rpms till I fixed it, If you do take it off, let it soak in some diesel for a while then clean it. I would also run some seafoam throgh the intake a couple time via the brake booster hose. for that matter I would take the time to clean all your emission systems. including egr, MAF, IAC, the speed sensor thing whos name eludes me at this time. and anything else you can think of.

 

[shadow1]

the TPS do you mean?
So i should first replace the pcv valve, which will hopefully stop the blowback.
Then clean out the rest of those sensors?