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Hello. I'm new to the forum. I have an 82 CJ7 with a fresh rebuild 258 and the Hesco MPI installed by myself. At low power the engine runs fine. But under load, say going uphill or when giving a sudden throttle input in a higher gear, the engine begins to misfire or cut out as though one or more cylinders are not firing. If I ease up on the throttle it recovers. If not it shudders pretty bad until I do. If I go easy on the throttle the problem does not occur. Only under load. At cruise speed on the freeway it mostly runs good, but occasionally I do feel a slight power loss as though I am dragging a cylinder. The plugs are clean so I don't suspect an ignition issue. It acts like its running out of gas. Thoughts or suggestions much appreciated. Lou
I just helped a friend install a rebuilt engine into his son’s 2000 Jeep TJ with a 4 cylinder 2.5L, manual trans and 4WD. He got the engine as a long block so we only had to reuse the tin covers, ignition and fuel systems. He got it from a reputable nationwide rebuilder so we are not concerned with dumb mistakes like timing chain installed incorrectly issues etc. We installed distributor as described in the service manual (TDC on 1 of compression stroke with 3/16 pin thru Camshaft Position Sensor and distributor housing etc.). The crankshaft position sensor is a two bolt type so no adjustment needed. I’m aware the PCM controls the timing so we can’t do anything with that. I’m assuming the CKP is working because we are getting flashes from the timing light. When trying to start the engine it kicks and bucks with an occasional backfire thru the throttle body. We connected a timing light to number one and looked for the initial timing around the marks on the timing cover but it appears the mark on the balancer is showing up at about 50 degrees after TDC. We have triple checked everything (firing order, sensor connections etc.) but can’t figure out how to get it running. We tried putting the PCM in learning mode by disconnecting battery and holding positive and negative together for several hours to try to drain the capacitor that keep PCM memory alive. We also did the ignition ON, headlights ON and then OFF, ignition OFF procedure. After putting in learning mode we disconnected the fuel pump fuse so we could crank the engine long enough for the CKP to figure out what is going on. Does anyone have any ideas on where to look next?
Hi, I have a '89 Wrangler with the 2.5l. It pops/backfires back up through the intake whenever I give it throttle. There are no vacuum leaks. I have replaced every sensor. I have swapped out the PCM, no change. I have checked fuel pressure, 15 psi. At this point I found excessive play in the distributor when rotating the crank, so I pulled the timing cover and found the chain to be stretched, and the cam sprocket and crank sprocket timing marks were mis-aligned. Aha! I said, and replaced the timing set- I set the crank to #1 TDC on compression, rotated the cam forward so that the marks would line up properly, and installed the new set. After reassembly, I checked the distributor and made sure that it was pointing to 6 o'clock when the timing mark on the cover was at 0 BTDC. I then fired it up, and the issue remains. Backfiring through the intake. Could this be a camshaft or valve issue? What would be the next move?