Alright guys so I am posting this for my dad who is going through hell right now with his Ranger that has always been great to him. Truck is a 99 2.5 5speed with 230k on the clock. Has never had any problems until recently where the motor upon driving if comming to a fast stop it wants to die. Truck feels like it is running on 1 cylinder when it does it. Originaly he was getting a p0301 and p0302 code but he replaced the wires, plugs, and cylinder 1 and 2 injectors and doesnt get the code anymore. The truck does it the worst when it is starting to warm up, not when it is super cold or not to bad when it is has been running for very long. The truck will run fine on the freeway like there are no issues at all, and I can also raise the idle and it wont start to die when you release the gas. It will do it at rest in the driveway as well. Here has what has been done.

- Cleaned MAF sensor
- Unplugged every sensor under hood to run on base settings never changed anything
- Replaced Engine Coolant Temp sensor
- Removed CAT and ran straight header to see if exhaust was clogged
- Replaced Plugs/wires
-Replaced cylinder 1 and 2 Injectors
- Friend has a computer to scan vehicles like a laptop while you drive and the only thing it was picking up on was the cylinder 1 missfire prior to injector swap, and a front lazy 02 sensor. ran car without 02's same problem.

- Cleaned TB, and measured TPS.
- Truck has a new Timing Belt put on, this was put on after the issue. Same problem.

- Compreession check completed all cylinders over 180 except cylinder 1 is 160
- Took Intake off to inspect valves for carbon build up almost none. Very clean.
- Switched exhaust and intake coil pack to see if there would be any changes.

We are scratching are heads at this one, any help would be great!!

Thanks in advance, and sorry for teh long post.

 

I would say the ignition module that controls the 2 coils except I think you'd be getting an ignition error code if you had a problem there. Have you done a combustion leak test on the cooling system?

 

i would have guessed the cat but you already tried that, idk man, good luck

 

Have you tested the MAF? is it within specs?

 

I have not tested the output, I will today. I figured if it was un-plugged the computer would default to limp mode, and probably cure the problem if defective. Thanks

 

do you guys think it could be the Idle Air Control Valve? Symptoms I have read about sound similar.

Thanks Again

 

Never heard of one causing a misfire code, unless you had 2 different problems at the same time.

 

I know if you stop fast or slip out the fuel supply can be shut off which is easily reset by pressing a button. I don't know if rangers have them, but I know of cars having such safety features. In your case the truck does this while idling so....actually, have you checked your ground wire. Just a thought, I have had vehicles crap out on me all because of the ground wire. Check it out and sand down the metal if ya have to. Also check battery connections. If I think of anything else i'll be sure to let ya know. Good luck!

 

ok guys so just a heads up. Found teh issue tonight THANKG GOD, and it was the Idle Air Control Valve!!! This is alost funny. because my dad bought the sensor months ago, but tested the resistace from the one out of the box, and it was close to the one on the car so he returned it. The haynes manual said if the resistance fell between 7-13ohms it was okay. The resistance on the bad valve was 10ohms but obviously it did not work properly. I have also read online that there is not a way to test these valves properly, so we gave it a try. Anyways it worked, hopefully this helps someone else who might be in the same boat some day.

 

Glad you got it fixed.

 

Thanks. Hopefully he will get atleast another 100k out of the truck. Truck still looks great, and drives great.

 

Good news!

 

on my 2.5L 98 when ever i rev it up beyond 4500 or so and come back to an idle it always wants to stall out has only stalled twice justs rides rough until more gas.. not much help but i have the same issue