Same ol question, can't find answer, My Truck Won't Idle.

[Frankenstine]

Hello everyone.

I joined this forum in hopes someone can help me out.

I know this question has been asked a 1000 times, but none of the answers have worked for me unless I missed something.

I have a 1995 Ford Ranger with a 2.3 engine. I've had this truck for 10 years with no problems and it has 370,000 miles on it. It still runs like new, (at least it did a month ago).

A month ago, my gf was driving it and was saying it had no power and would cough and sputter when going up hills or accelerating. She continued running around until it died in the middle of the road 20 miles from home. She said it would crank over but wouldn't start. I proceeded to rescue her. I grabbed the chain and some starting fluid and headed out. Once there and got the truck in a safe place, I immediately checked fuel pressure the best I could by pressing the pressure valve and it shot fuel out. Next, I shot ether directly into the carburetor twice but didn't even sputter. I checked spark and had a strong spark. I then pressed slightly on the gas peddle and it started, but I had to keep the RPM's around 1200 to get it home. At that point, it no longer sputter going up hills. It ran strong except at idle, which it wouldn't idle at all.

Since then, I've replaced the TPS and MAF sensor and the EGR valve with known good used ones. I also replaced the Idle Air Sensor with a new one. There are no codes. I also tested the fuel pressure

One more thing: When I unplug the Idle Air Sensor, it still doesn't idle on it's own but it will throttle down to a normal idle as long as my foot is on the peddle. As soon as I plug the sensor back in, it dies. When I restart the truck, I have to keep it running at least 1200 to 1400 RPM's.



Any help or suggestions would be very much appreciated.

 

[boominXplorer]

Check the compression. I had a buddy that had similar milage but started to loose power past 300k. By 350k all cylinders were under 100psi with the middle ones being 50-60 psi. It still ran, it just would barely make it up hills.

 

[Frankenstine]

Check the compression. I had a buddy that had similar milage but started to loose power past 300k. By 350k all cylinders were under 100psi with the middle ones being 50-60 psi. It still ran, it just would barely make it up hills.

Could it still be a compression factor when I unplug the idle air sensor and let it idle down? Just wondering since this problem came on so quick. A compression check is going to have to wait till this coming weekend.

 

[Frankenstine]

OK, I just did a compression check this morning on 3 of the four cylinders and got about 128, 135 and 1 about 132. The last cylinder is tough to get at but might still do it.

Also took the new idle air sensor off and replaced it with a known good one but it didn't help. This is the third one so apparently, the original sensor was good.

Then we started the truck with the pedal depressed and let it run at about 1800 rpm. Sounded good, no miss or anything but would not idle on its own. The slowest it would go is about 1200 to 1400 RPM. Once it dropped below that, it stalls.

Next, we unplugged the idle air sensor and started it. With the idle air sensor unplugged, we can get the truck to idle down to it's normal speed of around 650 rpm. But it still won't idle without your foot on the peddle.

Next, We started it and ran it at about 1800 RPM and unplugged the MAF sensor and it continued to run without a skip.

We also checked for codes and PO102 came up, after all the codes were cleared and the truck was restarted that same code came up again. So I'm going to replace the MAF.

But if this code was present, why didn't the check engine light come on?
In fact, there's no check engine light that comes on even when turning the key on.

Could that light be burned out?

 

[Frankenstine]

FIXED.

It was a bad Mass Air Flow sensor. Not a dirty one, but a bad one.