IDLE LOPES

[frankgeno]

1992 Ranger 2.9 L V6 AT 4WD 135,000 miles The engine idles poorly, lopes, kind of like if there was a racing cam, lopes, I found one vac line split and replaced it. I have looked for others all look okay to me. Driving the truck runs fine but come to a stoplight, LOPES. What do I look for???

 

[franklin2]

Ckean the throttle body and idle air control valve. They get gunked up and won't let air through properly for control of the idle speed.

 

[rubydist]

Yeah, most likely the idle air control is sticky. I have cleaned them in the past with poor results (they work better but only for a short time, in my experience) so it will likely need replaced.

 

[rusty ol ranger]

Unplug the IAC at idle and see what it does.

If it idles low but smooth chances are its the IAC. You could also try giving it a whack with a wrench or small hammer and see if it changes.

Also pull the vacuum line off the fuel pressure regulator and see if theres gas in the hose. Espicially if youve noticed any MPG drop. FPRs are a known 2.9 weak spot.

Either part runs around 50 bucks and is easy to replace

 

[ericbphoto]

I thought idlelopes were a medium sized deer with 3 corkscrewy horns and a Long, straight rainbow colored tail.

 

[frankgeno]

I installed a new IAV and no difference with the idle. I bought a scanner for computer codes and no codes were present.
I sprayed starting fluid along the vacuum lines and did not detect any difference in the running of the motor so have to assume no vacuum leaks in the lines.
I put on a new TPS and no difference. Air filter is clean.
I pulled the vacuum lines from the fuel pressure regulator and no gas in the hoses.
truck was built in Canada so no MAF or EGR valve
I put a can of Seafoam in the gas tank and also pulled a vacuum hose off the intake and stuck the other end into a can of seafoam and ran that through the engine and no difference.
At a loss what to try next..

 

[franklin2]

What happens when you turn the idle stop screw in a little bit? Mark it with a magic marker so you can put it back. Raise the idle a little bit, does it stop loping?

 

[venom97]

check your fuel pressure regulator. My 92 explorer was dumping tons of fuel into the cylinder and was causing the same thing. I pulled the vac line off the regulator and found fuel being pushed through it. Something to check out thats pretty easy.

 

[franklin2]

check your fuel pressure regulator. My 92 explorer was dumping tons of fuel into the cylinder and was causing the same thing. I pulled the vac line off the regulator and found fuel being pushed through it. Something to check out thats pretty easy.

He said in post 6 he already did that.

 

[rusty ol ranger]

The PCV is functioning properly right?

Try taking the hose off that goes to the brake booster to and plug the port. Bad boosters can cause massive vacuum leaks.

At the top of the 2.9 forum is a sticky post on how to adjust the idle on a 2.9. But i wouldnt do it untill youre at the very end of checking EVERYTHING