2.9 Misses and dies at idle only

[xploridaho]

1988 4x4 Ranger. Things I have already replaced: Co2 sensor, water sensor, map sensor, fuel filter, plugs, wires, dist.cap rotor, gas tank. Runs great out on the road, but misses at idle. If I set at a stop for a couple minutes with it it will die. Idles rough at low rpms, but runs great any other time. Help please, thank you.

 

[cappin90]

my 4.0 does the same thing and i have no idea why, some one should answer this

 

[TheMoon]

Hi. Take a look at the Idle Air Control valve (IAC). My 1987 had a stumble at idle and would occasionally die even though rpm's above idle were smooth. Once I replaced the IAC, the idle is smooth and off-idle response was greatly improved. You can replace your altogether as I did, or yours may only need a good cleaning.

-TM

 

[DisturbedMXer8]

Yes, definitely check IAC. I have all kinds of issues with mine and have to constantly clean it (because I'm stubborn and refuse to replace it until it fails completely), otherwise I get a nice stumble every now and then at idle, and it will occasionally die.

 

[xploridaho]

Ok, this problem is now a constant thing. If I sit and idle after about a minute the engine just dies. I ran the codes on it and I got speed senor and pick-up coil bad codes. Will either of these make the engine not idle right?

 

[Big Jim M]

Yep!

You better know they will.
Big JIm

 

[xploridaho]

Big Jim, thanks for the info. Now I have a decision to make, take the distributor out of my other engine, or is it time to remove the engine in it and put in the other one. The one in it runs, but is starting to rattle and smoke slightly.

 

[sjr53]

Changing the distributor isn't too tough of a job. A different distributor will probably mean the new on will not go in exactly the same, but just find the closest spot that allows it to drop all the way in.

 

[xploridaho]

Ok, I changed the speed sensor and no difference.

 

[robertc1024]

Did you clean the IAC though? Mine would't idle for anything. Pulled the IAC, doused it with gumout and haven't had problems for a year.

 

[xploridaho]

I had cleaned it already. I even changed it with the one off my parts truck, not difference.

 

[kimcrwbr1]

Did you reset the computer disconnect the battery for 20 minutes it could be running on old values.

 

[xploridaho]

Havent tried that, didnt realize I needed to

 

[brett1989]

Check your fuel pressure regulator, my truck did the same thing til i replaced it, and shop around for one if it is infact that. Alot of auto stores are looking to get between 75 and 90 bucks for one

 

[kimcrwbr1]

Havent tried that, didnt realize I needed to

Erase the memory first and then disconnect the battery for 20-30 mins to reset the computer. Then run it at medium speeds cycling the a/c if you have it. The computer will set new values and then run the codes while the engine is up to temp. Plugs wires cap and rotor are a good idea also if you haven`t done so recently may as well get it ready for winter now. The ignition see`s alot of voltage so it is recommended to replace the wires reg I just do it every other year along with the PCV valve. Your actually money ahead doing this in mileage alone.