Hi folks, I've got a problem with my 92 2.3L Ranger, and could really use some help. I've had an intermittant problem for a year or more. The symptons are customarily at startup, but occassionaly the symptoms just continue startup and long term runnng too. When i start the cold motor it wants to die and sometimes does, and then starts and idles rough. I can see the tach trying to idle at about 900rpm, but it stumbles and drops to about 600, and then back to 900 etc and keeps doing this. And of course the CheckEngineLight comes on too. Once I drive it--its kinda underpowered and rough, but not horribly so-it runs good enough to keep up with average moving traffic--but definitly low power-somethings off and the check engine light remains. This can sometimes totally clear up in about 9 miles or so, and has been lately, including the check engine light going dark but last year it would get into this funk and just keep doing it pretty much all the time. But like I said lately it seems to clear itself up after about 9miles @ 55mph and stays that way until it sits overnight or for a day or two and then starts all over again.

I've done everything I can think of--the same code comes up EGR sensor! I've replaced it and its sensor plus the other device? that controls the vacuum tubes to the EGR and still it continues to intermitantly misbehave. I've repeatedly taken it to the same mechanic--and it seems to run good when he has it--wouldn't you know--but he defintely sees that the EGR code has been triggered. This most recent time--and I've been every couple weeks-he told me that the egr sensor was sending the wrong voltage code etc--I may not be saying this right--but anyway he slightly shortened the shaft of the sensor to make it read the correct voltage--As I recall 3.0 to 3.5 ? I think that's what he said. Some numbers like that.

Anyway now I'm wondering, can I better sort this out myself, or should I just give up on this guy and go somewhere else. He's no longer charging me, but it seems futile to keep doing the same thing and getting the same result. Meaning should i keep taking it to him? Its fine at his shop and then the very next morning it runs crappy as usual and the check engine light comes on again and stays on for some time--and each time I take it back to him he says Yes its the EGR code again. He resets it, and checks things and I drive off with everything good until tomorrow's startup.

I bought the truck new in 1992 and around 2000 I took the motor to a machine shop and had it balanced/rebuilt etc. Its a high mileage truck. It doesn't burn oil or smoke or anything. Obviously I've looked at all the plugs/filter/sensors and wirng as best possible, and so has the professional mechanic I guess. Years ago I replaced all the injectors and got new coils etc and plugs wires and all--and he's supposedly a pro mechanic that would be able to diagnose any typical tune up problems. I don't know what to do.

Any ideas guys. Could it be a bad PCM?

Help

 

I would take apart the IAC and clean it to see if that smoothed the idle, and also clean the throttle butterfly. Does it idle up when cold and gradually slow down in steps if you strart it and let it sit in the drive for a few minutes?
I would check all the readings on the temp sensors. The ACT and ECT are intake air and coolant temp. The ECM (computer) only knows what those sensors tell it, and will only complain about them if they are totally broken. In other words, if the resistance is 39 ohms, the engine is at xxx degrees. Even if the engine is actually at x degrees, either coolant or air charge, in this case. It does not have anything to reference against to 'know' that the temp sensors are full of beans and lying their little nodes off. So, it sends the amount of fuel it is programmed to send at that temp, even if it is wrong. You could try running with either or both disconnected and check the results when the ECM uses the default or 'limp-home' values.
What EGR code are you getting? There was a problem I remember where the EGR valve position sensor would be just off a tad and would cause a code to be thrown. It was something along the lines of the replacement sensor from Ford would not drop to the proper ohms when closed, or send the proper number when fully open, but that was several years ago.
tom

 

Thanks for your help. I'll follow your suggestions as soon as possible, and get back to you. I recall off the top of my head exactly what the EGR fault code is or was. I'll find my notes and or put a beep type code reader on the truck and get any current codes, but I'm kinda busy with another project and Ill try to get to Friday. Thanks I 'm really stuck on this I need your input. Tom

 

Thanks "tomw" for your suggestions about testing the ACT and ECT sensors. I disconnected them and sure enough the truck ran better. I replaced them both and it hasn't run so smoothly sense I don't know when. Its too bad my mechanic didn't suggest this. I don't know why. I would have got to it sonner, but I'm building an old 58f100 into a prostreet truck and I'm getting towards the end and its sucking up all my time. And the Ranger--though not running good--at least runs--better than my long time up on blocks 58. Thanks for all your help.
Tom