Rough idle after starting, and whining noise.

[74duster318]

My truck has been idling rough, soon after I start it. It lopes up and down to the point where it will almost shut off, then the engine will correct itself and run normally for a bit. It does it a few times before it warms up, then it's fine.

The other problem is a whining noise that sounds like it's maybe fuel injector related? Something that randomly comes about, and sometimes happens when starting from a stop. If I rev the engine past about 1500 rpm it stops...however if I let it idle while it whines, the engine eventually just shuts off.

It's my 99 4.0 ranger by the way.

Any clues?

I just changed my plugs, wires, and coil pack...the truck runs better, but sill has all the problems. It's been doing this for quite a while. What should I do next?

 

[adsm08]

Idle issue sounds like an IAC issue. Injectors make a click or ticking sounds, not a whine.

My first suspect for an engine related whine is always the P/S pump and then other FEAD items.

 

[Ranger44]

Id have to agree.

The idle issue and whining are kind of a dead giveaway.

IAC

 

[straycat]

If you want to keep that idle and whinning noise just put a badge on the truck that says 'Blown and Injected'...people will fear that for sure.....lol

 

[74duster318]

I suppose the rough loping idle could sound like a heavy cam too...lol.

Ok, so it sounds pretty obvious that it's the IAC. I'll order a new one at work tomorow when we finally dig out of our 5 foot snow drifts. I'll post again when I find out if that was the problem.

I'm curious as to why we don't have anything in the tech library about the IAC and how to clean/replace it. It should go right along with the MAF section, or the 4.0 engine troubleshooting.

Thanks everyone!

 

[74duster318]

Took not even two minutes to change that puppy out with a new one this morning, and now the idle is perfect. The IAC was definitely the problem. The old one was nasty and sooty inside, not suprising since it probably wasn't touched in all of it's 135k miles.

Thanks again guys!