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Showing results for tags 'mopar efi conversion'.
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Vehicle background: 1983 Jeep CJ7 Laredo 4.2 with Hesco MPI kit Westside Performance Valve Cover (thick cast aluminum replica of the stock cover) T-18 four speed Dana 300 Dana 44 axles front and rear (4.27 to 1) 36" Swamper TSLs I bought this Jeep in 2003 odometer had 145,000 miles, now has 170,000, it does not get driven all that often. Plaque on the motor reads "MOPAR Performance", it is a mopar 4.2 crate motor with a remanufacture date of 1998. My estimate is that the motor has ~80,000 miles on it. Issue: Recently failed low speed NOX during my last CA smog test, measured 1,322 and max is 1,066 (fail). High speed NOX readings were measured at 948 and max is 968 (pass). For the last 3 or 4 tests high NOX have been an issue. Before I went to test my jeep I changed the oil, it was a quart low. I removed and cleaned the plugs. The fourth plug from the front had quite a bit of carbon buildup. After the test i decided to do a compression test. Got the Jeep up to operating temp and did my first test dry. Readings from front of motor (water pump) to back were 121, 128, 123, 137, 124, 122. The fourth cylinder had a compression reading about 10% greater than the others. This was the same cylinder that the spark plug with the carbon buildup came from. Next I performed the same test but this time adding two squirts of oil to each cylinder before the compression test. My readings were within 1-2 psi of my dry test. My diagnosis is that the cylinder head needs to be rebuilt. The cylinder head is worn letting excessive blow by enter the combustion chamber through the CCV valve which vents to the number 4 cylinder where the oil is burned. This is why i was a quart low when I changed the oil and why cylinder 4's spark plug was all coked up. Does this sound reasonable? Can i rule out rings in this case? What do you think? Thanks for the help!!
Happy Thanksgiving to all! I've posted before that my CJ-7 has a Cherokee 4.0L in it, but it's not really that simple Here is the history as I know it or can guess from some evidence: 1. Originally a 258/4.2L straight six with the FrankenCarb--this one was sold in California, so I'm sure it was extra-special. 2. MOPAR EFI kit added to the 4.2L. It seems this addition happened sometime after 2000, as the MOPAR labels for the kit have a 2000 copyright on them. I learned from the shop that did most of the work on this Jeep that the lady I bought it from purchased it sometime around 2001. It was owned by 1 family prior to that (1983-2000?). I suspect the Skyjacker lift and sketchy paint job happened about the same time to make it ready to sell. 3. The 4.2L finally gave up in 2014. This engine was replaced with a junkyard 1995 Cherokee 4.0L last May; engine had about 155K on it at that time. I never really knew which version of the MOPAR EFI kit I had, OBDI (with fuel return line) or OBDII from the newer models (returnless). There was also the option that they pulled a complete 1995 engine including the EFI and junked the old MOPAR kit. I just didn't really know. I've done some more research and taken some pics to see if anyone can confirm what I've come to believe. It seems like my system matches the pictures I've seen of a single rail EFI system. That would mean it is: 1. 1997 and newer 2. Returnless 3. OBDII I mostly ask these questions because I've been looking at performance options for whenever I'm forced to rebuild this engine. I really think I want to leave a Jeep engine in there, as opposed to a small block Chevy, for example. It seems like most systems (supercharger, programmers, etc.) are dependent upon the OBDI VS. OBDII distinction. With a 1995 engine, I wasn't sure which items I should be looking at. Assuming this is a 1997 and newer-style EFI kit, I assume I should only look for performance items for the newer model engines, correct? I don't think there was much other than heads (I have the supposedly better casting) that varied in those mid 1990's engines, other than the EFI/PCM. 1. Can I conclusively say this is a returnless/1997 and newer EFI kit? 2. Is this the OBDI/OBDII port I'm showing in the picture? It is about 8" down the main wire harness from the MOPAR EFI kit PCM. Regards, Case