Took my Yj through some prettydeep mud a couple weeks ago. Ran fine until then, but keep getting a check engine light. At first it was on constantly, so i did somelooking, and found i had a craked header. Replaced it, along iwth all new exhaust, and o2sensor. Now check engine comes on intermittantly under load(accelerating up hills) but i can reset it by turning ingnition off and pop starting while still driving. Also it now idles a bit hight than it did originally. Any ideas of where to start diagnosing and or cleaning ? Already disassembled throttlebody and cleaned it and the idle air control valve, but still not fixed. Runs fines, just sputters every now and then
will do.....also i am getting codes for the ignition circuit, mat sensor, o2 sensr and tps. Are these all on the same circuit, and possibly, im getting a bad signal?????i know the wires all run into the same harness, but could this be a possible ecm issue??
Thanks all. Checked all codes, getting an 11 24 33 and 21...11 is generic ignition, 24 is mat sensor, 33 is ac-which i dont have, and 21 is o2....will try cleaning out the ecm....seems like a bigger problem than all sensors going bad at once.....
Clean all the connectors for all the sensors and electrical you can lay your hands on including the ecu connector and seal them with dielectric grease. Mack sure you remove the backshell on the ecu connector and get it too. Get the speedo connector on the tcase. It shares the feed power and doesn't show faults when shorting. Code 33 is a BS code from common diagnostics from the XJ's and should be ignored on the YJ. It is important to do the battery disconnnect to clear the ecu fault codes because it will run in default mode until the codes are cleared.
After replacing the cracked header, cleaning the ecu, replacing all plugs and wires, coil cap rotor, checking timing, 2 02 sensors, turns out my tps was bad...had a skip right in the middle....odd that it would set so many codes.but there isn't one for itself...easy to check to...unplug the harness and set a multimeter To ohms....put a lead on the two outer pins and turn the throttle by hand...resistance should change smoothly...if it jumps to zero set any point it's bad..
And you never saw the tps code! The other codes make sense. The ecu does a check and compares vacuum against the tps position. It saw the 2 didn't match so it threw the map code. Tps for the fuel injector too. At 0 you are telling it you are full throttle so your injectors were dumping fuel that the engine couldn't burn. It makes sense but I never would have gone there in a million years with your symptoms. Thanks for posting back.