Lots of idle issues on this forum but can't find one similar to my experience.

88 ranger. 2.9L manual.

Just bought this truck. It ran great when I bought it. After a day or 2 it would idle rough. Almost die but it wouldn't. No check engine light. It seemed to do this intermittently. Some times I'd start it and it be fine. Other times I'd start it and I'd expect it to die at each stop light.

Now for the last couple days it dies on every start up. It won't idle. It'll start right away and then die. I can keep it going by keeping the engine rev'd but the check engine light is one. If I keep it running and start driving down the road it'll drive with the check engine light on for about 5 minutes. Then the light goes out and it runs like normal, even at idle, until I shut it off. Then it's the same story at next start whether it's right after I shut it off or hours later. It doesn't seem to matter whether the engine is hot or cold. When the check engine light is out, it runs great the rest of the time whether at speed or at idle.

To me it sounds like a sensor is on it way out. I figure if it was vacuum, it happen at every idle, and if it was fuel it happen all the time or at least every idle. Any ideas?

Tried to get a code at parts store but the reader wouldn't work. It couldn't tell it was plugged in the the truck for some reason.

 

Scan for trouble code clues & post All code Numbers found.

 

That's an issue. i don't think codes are going to happen. That parts store is the only place that I coukd find that can pull codes off an 88. Either their machine is bad or my plug is bad in the truck. Code reader won't register that it's plugged into a vehicle.

 

Instructions from my Actron scanner owners manual.

Warm the engine then

1 test scanner battery
2. Connect BOTH test connectors to the scanner
3. Put scanner hold/test switch in hold position
4. Turn ignition key to the run position.
5. Put hold test in test position

If this is what was done then either the scanner is shot or there is a wiring problem in the wiring to the PCM/computer

You can also pull the codes using the CEL/check engine light.

Google pulling EEC-4 codes with the check engine light.

The connectors for the scanner are under the hood near the heater blower. One connector is 3 or 4 wires, the other is a single wire. Both must be plugged into the scanner.

 

If this is what was done then either the scanner is shot or there is a wiring problem in the wiring to the PCM/computer


I assume the wiring is shot but it 's worth a look to try again and make sure we do it right.

You can also pull the codes using the CEL/check engine light.

Google pulling EEC-4 codes with the check engine light

I'll try that

 

A1 cardone sells reman PCM's/computers. I've heard that they have a very good tech support. Try doing a goggle search on "A1 cardone tech support" and give them a call. They might be able to tell you how to test and see if your PCM is bad.

 

Thanks for the scanner advise guys.


Here's an update on the truck.
now that i finally got a chance to dig in the other day

I was sure a sensor was bad because if kept tryin to start it and wiggled the wires at each one betweens starts, eventually i'd get a "good" start with out a cel and bad idle so i assumed i had a broken wire in there.

I gave it a basic tune up as an excuse to go digging around. Plugs, wires, cap rotor, fuel and air filters plus some valve cover gaskets because it needed them. I took the intake plenum off to make room and replaced those gaskets. Cleaned the iac and throttle. Both looked good.

However i found a couple spark plugs that were loose(or just barely hand tight) And all of the plugs had a wide gap. The manual says .44 but they were all at .55-.65. They looked good other then the gap. After i put it together, no more light or bad idles.

My theory is the hand tight plugs were seated just enough that when the engine warmed it would expand just enough on the plug threads to close the leak. That mixed in with the wrong gap kept it running bad. I don't know if thats's what it was but that the only thing i could find. Maybe the valve covers were leaking oil onto the plugs to affect them.

Since it idles now i could confirm no vacuum leaks and i didn't find any broken wires.

I was supprised it was fixed from just a tune up.

 

While I said no more bad idle, it still has a very slight hesitation at idle once in a while. Usuall when warm. Not at start up. It's not much. It idles at 900. It may dip to 800-850 at a stop light but not everytime? Does that indicate anything to anyone?

 

An occasional slight dip in idle rpm could be almost anything on this vintage vehicle.
Where are you now on getting All of its past & present due scheduled maintenance replacement items up to date????
Did you use the Specified Ford ignition parts, or a known good brand, or the least expensive after market parts you could find????