parkia86 Posted July 29, 2017 Share Posted July 29, 2017 So here it goes: 1987 Jeep Comanche I have a 4.7L stroker installed, had no issues at all for about a year. I replaced the ECU with an 89 a few days ago Just replaced the CPS (must have gone through 3 or 4 of these things in the last 4 years The exhaust was replaced about a year ago due to rust. And it fires right up and runs very strong, however, once its been running for awhile and i give it gas... it starts bucking a little bit... I smelled some burning and examined under the truck and found the Catalytic converter was RED HOT! I Have never seen this before and i am long time comanche owner (10 years same truck). My question is: Where is the most logical place to go? It worked fine with the 87 ECU prior to CPS replacement, do i need to retune the fuel delivery for the 89 ECU? Is this a sign that the ECU is bad? Has anyone else seen this? Could it be the O2 sensor is bad? It doesnt appear to be anything mechanical... the only symptom i am seeing is the red hot cat. I can test fuel pressure at the rail but all of the injectors were replaced, regulator was replaced, ICM and Coil were replaced with the install of the Stroker. The only thing different is the ECU. Link to comment Share on other sites More sharing options...
MuddFoot Posted July 29, 2017 Share Posted July 29, 2017 If it's getting red I'd say it starting to get clogged. I had one get red hot then not run the next day till I cut a slit in front of it. Sent from my Z981 using Tapatalk Link to comment Share on other sites More sharing options...
HOrnbrod Posted July 29, 2017 Share Posted July 29, 2017 That stroker sounds like it's running lean. Very lean. If you don't have an Air/Fuel gauge installed on the vehicle, (every stroker should), bring it somewhere to test the A/F ratio (mixture) before the pistons melt. I suspect the new ECU is the most likely culprit. I doubt it's the O2 sensor; when they go bad it usually makes the engine run rich. Link to comment Share on other sites More sharing options...
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