'93 4.0 Running Rich, Rough Idle, Stalling Out
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From: Chicago, Illinois
'93 4.0 Running Rich, Rough Idle, Stalling Out
1993 Ranger XLT 4.0 A4LD Automatic
I can't for the life of me seem to pinpoint this issue whatsoever. The truck has run rich since I bought it last year. There was a multitude of issues, many of which were likely because it had a CA 2.3L ECU in it. The transmission has been fully rebuilt. Sorted some of the issues out and put a lot of work into it to stop it from leaking everywhere and to make it more reliable. I now cannot figure out why it is dying out on me. Starts right up, RPMs slowly drop as they should and then it begins to fluctuate right after that initial fall. Accelerates fine but just 10 seconds or so after coming to a stop, the RPM begins to fluctuate between around 700 and 500 and it will die out if the throttle isn't feathered occasionally. This happens whether or not the motor is warmed up, both in Drive and Reverse, and even in Park albeit more slowly. It is running rich enough to burn your eyes and guzzles gas.
Among the parts that have been replaced since last year that could possibly pertain to any of these issues:
-O2 sensors
-Spark plugs
-IAC valve
-Timing chain
-TPS sensor + wire harness
-MAF sensor
-Majority of vacuum lines
-Upper intake manifold gasket
-ECU (junkyard one, capacitors replaced, traces inspects, one was repaired)
-Fuel filter
The original ECU was throwing a bunch of false codes for parts I didn't have along with one for the TPS being out of range. It was impossible to lower the voltage to anywhere lower than 1.2V or so, even while unplugged. With the new ECU, the voltage had no change and currently sits around 1.3V, well above the 0.99V goal. It's been so frustrating with the voltage over the many months and I'm tempted to just run a resistor on the wire just to get the voltage down to spec. Despite this, it no longer throws a code out. I've checked as many ground as I could and they all seem good.
The only code the ECU throws out now besides the 998 and 111 is a 157 MAF code. The MAF was inspected, contacts were cleaned, and the sensor was replaced along with it's housing. The code hasn't change even after clearing the KAM in the computer overnight. I'm sure the high TPS voltage is at least part of the reason that the truck is running rich but I'm not sure if it has anything to do with the rough idle. And for the record, yes, I checked the FPR for gas in the vacuum line and there was none. I even ran a clear hose and didn't see anything. Not sure about the wires but I don't think they're original, and yes they're in the correct firing order. I thought I read somewhere that if the throttle is read as open to the computer, then the torque converter might have trouble engaging which would cause a rough idle I would imagine.
In summary. The truck is dying out rather quickly in Drive and Reverse if not on the throttle. In park, it will die out, but it will run for longer compare to D and R, even when fully warmed up. Oddly enough, In neutral, it will run very smoothly, although around 900 RPMs, the higher than spec idle probably because of the TPS voltage. Any help would be greatly appreciated, and I am willing to conduct any test people think I should do.
I can't for the life of me seem to pinpoint this issue whatsoever. The truck has run rich since I bought it last year. There was a multitude of issues, many of which were likely because it had a CA 2.3L ECU in it. The transmission has been fully rebuilt. Sorted some of the issues out and put a lot of work into it to stop it from leaking everywhere and to make it more reliable. I now cannot figure out why it is dying out on me. Starts right up, RPMs slowly drop as they should and then it begins to fluctuate right after that initial fall. Accelerates fine but just 10 seconds or so after coming to a stop, the RPM begins to fluctuate between around 700 and 500 and it will die out if the throttle isn't feathered occasionally. This happens whether or not the motor is warmed up, both in Drive and Reverse, and even in Park albeit more slowly. It is running rich enough to burn your eyes and guzzles gas.
Among the parts that have been replaced since last year that could possibly pertain to any of these issues:
-O2 sensors
-Spark plugs
-IAC valve
-Timing chain
-TPS sensor + wire harness
-MAF sensor
-Majority of vacuum lines
-Upper intake manifold gasket
-ECU (junkyard one, capacitors replaced, traces inspects, one was repaired)
-Fuel filter
The original ECU was throwing a bunch of false codes for parts I didn't have along with one for the TPS being out of range. It was impossible to lower the voltage to anywhere lower than 1.2V or so, even while unplugged. With the new ECU, the voltage had no change and currently sits around 1.3V, well above the 0.99V goal. It's been so frustrating with the voltage over the many months and I'm tempted to just run a resistor on the wire just to get the voltage down to spec. Despite this, it no longer throws a code out. I've checked as many ground as I could and they all seem good.
The only code the ECU throws out now besides the 998 and 111 is a 157 MAF code. The MAF was inspected, contacts were cleaned, and the sensor was replaced along with it's housing. The code hasn't change even after clearing the KAM in the computer overnight. I'm sure the high TPS voltage is at least part of the reason that the truck is running rich but I'm not sure if it has anything to do with the rough idle. And for the record, yes, I checked the FPR for gas in the vacuum line and there was none. I even ran a clear hose and didn't see anything. Not sure about the wires but I don't think they're original, and yes they're in the correct firing order. I thought I read somewhere that if the throttle is read as open to the computer, then the torque converter might have trouble engaging which would cause a rough idle I would imagine.
In summary. The truck is dying out rather quickly in Drive and Reverse if not on the throttle. In park, it will die out, but it will run for longer compare to D and R, even when fully warmed up. Oddly enough, In neutral, it will run very smoothly, although around 900 RPMs, the higher than spec idle probably because of the TPS voltage. Any help would be greatly appreciated, and I am willing to conduct any test people think I should do.
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Hsranger
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May 17, 2022 09:05 PM
