4.0 sohc running rough
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Joined: Sep 2008
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4.0 sohc running rough
I have '97 explorer 4.0 sohc that suddenly gave a flashing check engine light and began running very rough. Autozone read the code as a misfire in #4. The plug was black but not that bad. Plugs were replaced and it ran awesome for about 3 weeks. Then same problem came back. Wires were changed as well as coil pack. Verified spark on that plug and also changed fuel injector in #4. Nothing changed. Exhaust fumes are extremely strong when running around engine compartment. I have done a compression check and all cylinders came up within a few pounds of each other at about 140 psi. Changed egr pressure sensor also. Removed egr valve and it looked pretty good. Able to suck the diaphram open and it appears to snap closed when released. I replaced the intake upper and lower gaskets. The engine light came back on after all this work (still was not running right) and now it gives a lean condition left bank. Engine starts and idles okay. When raising the accellerator it is definately missing and the worst at about 2500 rpms but smooths out the higher the rpms go. I also cleaned the maf with maf cleaner. I had this put on a diagnostic before the engine light came back on and the only thing they wanted to TRY was the intake gaskets which I had already done twice to make sure they were right. Please help, I am going crazy. This is the second motor and it only has 65k miles on it.
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Joined: Apr 2004
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From: Southeast GA
Have you checked the fuel pressure regulator? My ex had one years ago and that was the only part I ever changed in over 300,000 miles. The best I recall someone told me to unplug the vacuum line from it and if it didn't change the way the engine idled, it was probably bad. It was bad and it caused some of the same problems you are describing (running rich, etc)
just my.02
Randy
just my.02
Randy
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Thanks for the advice. However it does not seem to be the problem. I just stopped messing with it and now the CEL has gone off but it is still missing. Retightened the upper manifold bolts but don't know if that is a vacuum leak problem or not. No result with the starting fluid in that area. Thanks
