1990 Trooper 2.6 - 3 months of troubleshooting and I finally solved the big problem - details

FYI "for the group" hope this can help someone else with the same problem
Hooorayyyyyyyyyyyyyyyyyy for Me!
I posted the below on June 6, 2005. I never heard any suggestions so I
kept on pounding dirt until I found and solved the probem. My problem was extreme detonation coupled with poor performance and "no idle". The problem was finally isolated to a bad "head gasket" in the #4 cyl. area . the leak was not shown via moisture in the exhaust or badly during the compression test that I performed earlier. Finally I used the fine spray tube of an aerosol Gummout and sprayed carefully around the seam of the head and block and after nearly giving up, "low and behold" here shows the lead at the most rear portion of the cyl head nearly up against the firewall. And it goes without saying that I also would change the timing belt due to some stretching during the removal process and also a good opportunity to put a new timing belt on.
Gloating a bit sorry. I followed the advice from many and always was led down a dead end as far as what could have been the culprit. Normally, I'm the kind of person that has the worst success rate at solving a difficult Isuzu mechanical problem.
Thanks for listening,
Ern ------------------------------------------------------------------------------------ I have been down with this problem for over 6 months. I would be enormously grateful if anyone could help me with further advice. :) I have had a very bad pinging problem and rough performance and it won't idle. this is a 2.6L 4cyl with approx 97k miles. So far I have tried the following based upon much "on line" expert advice to no avaail: I drained the fuel and filled with premium. I used the fuel anti'freeze additiive incase any moisture was in the fuel tank. I did find a bad fuel leak in the fuel cross over line at the fuel filter (near to the fuel tank) I went ahead and changed the fuel filter while I was in that area. (Could some dirt/debris been sucked into the fuel line damaged area and make it into one of the fuel injectors??) I went ahead and rodded out the orife's of the EGR valve down into the engine block with a long fine stiff wire (kept this up for over 1 hour of rodding out). I tried all possible ign timing adjustments. I changed the routine parts inside the the distributor, i.e.: rotor, new cap, all new spark plug wires and new Bosch plugs were installed as well. I installed a new 02 sensor and nothing abnormal appears in the Diagnostic codes at all. I have not changed or checked yet the anti-detonation sensor that is located someplace on the engine block. If it is at fault, I will need to determine some way of testing or by-passing of this sensor. Are there any other tips, tricks or suggestions that you might could have me try? Thanks in advance. I'm running out of possibilities to attempt. ......... Ernie

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