93 4-cylinder CEL comes on when it wants to

[ambec2]

Newbie to forum. Had 1993 for over 12 years. Ran great until April of last year. Backed out of driveway put it in first let clutch out jerked forward and stalled. It would not start, no spark. Changed coil still no luck. No cel. Tried again in about an hour, it started right up and ran for a few minutes and stalled. Sent ECU to be rebuilt by Wrangler fix. Ran well but didn't get jeep inspected. Started over the last few months and took it on short half hour drives. Last week I took it out and it ran very well, got back to the house and let it idle, that lasted about two minutes until it stalled. If cel is there it starts and idles fir about a minute or so unless I keep the rpm's above 1000. Waited until next day cel was on and it started. Turned it off and ran the diagnostic, Code 12 , 33, 53 and the first 5 and 2 1/2 for the final 5 when the cel flickered the tach did a dance and cel went out not to reappear until two days later. It's been starting the last few tries. Ran diagnostic again , Code 12 ,33 , 55.

Help,

 

[Chris]

Newbie to forum. Had 1993 for over 12 years. Ran great until April of last year. Backed out of driveway put it in first let clutch out jerked forward and stalled. It would not start, no spark. Changed coil still no luck. No cel. Tried again in about an hour, it started right up and ran for a few minutes and stalled. Sent ECU to be rebuilt by Wrangler fix. Ran well but didn't get jeep inspected. Started over the last few months and took it on short half hour drives. Last week I took it out and it ran very well, got back to the house and let it idle, that lasted about two minutes until it stalled. If cel is there it starts and idles fir about a minute or so unless I keep the rpm's above 1000. Waited until next day cel was on and it started. Turned it off and ran the diagnostic, Code 12 , 33, 53 and the first 5 and 2 1/2 for the final 5 when the cel flickered the tach did a dance and cel went out not to reappear until two days later. It's been starting the last few tries. Ran diagnostic again , Code 12 ,33 , 55.

Help,

Code 12 indicates that the battery has been disconnected recently, which is normal if you've done any work on the electrical system. Code 33 is related to the A/C switch; it might not be a major issue unless you’re having cooling problems. Code 53 is specific to the ECU, which suggests a problem with the fuel system or the ignition circuit.

What stands out is that you mentioned it starts and runs for a bit but stalls after a couple of minutes unless you keep the RPMs high. This could be indicative of a fuel delivery issue or a vacuum leak. Here are a few suggestions:

• Check for Vacuum Leaks: Inspect all hoses and connections for cracks or disconnections. Even a small leak can cause stalling.
• Fuel Delivery: Ensure that your fuel pump is functioning properly. You might want to test the fuel pressure while the engine is running to see if it's within specs.
• Ignition Components: Double-check your ignition system, including the distributor cap, rotor, wires, and spark plugs. They can sometimes be the culprits in stalling issues.
• ECU Revisit: Since you’ve had the ECU rebuilt, consider if there might be an issue with how it was reinstalled or potentially a fault in the rebuild. I wouldn't trust the rebuild unless it was done by Mark at https://wranglerfix.com.
• Sensor Check: Consider testing the crankshaft position sensor and throttle position sensor as issues with these can lead to irregular behavior.

Hopefully, this helps point you in the right direction!

 

[ambec2]

Code 12 indicates that the battery has been disconnected recently, which is normal if you've done any work on the electrical system. Code 33 is related to the A/C switch; it might not be a major issue unless you’re having cooling problems. Code 53 is specific to the ECU, which suggests a problem with the fuel system or the ignition circuit.

What stands out is that you mentioned it starts and runs for a bit but stalls after a couple of minutes unless you keep the RPMs high. This could be indicative of a fuel delivery issue or a vacuum leak. Here are a few suggestions:

• Check for Vacuum Leaks: Inspect all hoses and connections for cracks or disconnections. Even a small leak can cause stalling.
• Fuel Delivery: Ensure that your fuel pump is functioning properly. You might want to test the fuel pressure while the engine is running to see if it's within specs.
• Ignition Components: Double-check your ignition system, including the distributor cap, rotor, wires, and spark plugs. They can sometimes be the culprits in stalling issues.
• ECU Revisit: Since you’ve had the ECU rebuilt, consider if there might be an issue with how it was reinstalled or potentially a fault in the rebuild. I wouldn't trust the rebuild unless it was done by Mark at https://wranglerfix.com.
• Sensor Check: Consider testing the crankshaft position sensor and throttle position sensor as issues with these can lead to irregular behavior.

Hopefully, this helps point you in the right direction!

Thanks for your reply. Been starting and running well the last few days. Fuel pump was replaced when I brough it up to PA from OC MD.. Replace all ignition components at that time until we realized the rough running was the fuel pump. That was about 15K miles ago. Will follow up on sensors.