UNDR8D

For anyone experiencing these symptoms, it was indeed the ECU that had failed. I sent it out for a rebuild and the car runs great, ceteris paribus.

The CEL is not intermittent, rather, it "flickers" intermittently in conjunction with the misfiring. This indicates to me that there is a short of some sort that is related to the misfire and the flicker/inability to pull codes/inability to jump terminals.

That would make sense if the coil fed one bank only but the distributors are split between both banks with a coil to each so a bad coil will effect two cylinders on each side. Not just one bank.

I've read too many threads in which people spend $1000+ chasing problems around only to have it be something else. Those are all things that could be contributing to reduced driveability but the lack of a CEL at KOEO, no code retrieval with an expensive scan tool and no codes when terminal jumping leads me to believe it is primarily the ECU. Any response to those specific symptoms? Also, it is unlikely that an ECU would fail in those regards and not also effect running condition... Also, to edit my original post, it is not just running kind of poorly. This morning it all of a sudden went from running fine to extreme power loss, major hesitation, no acceleration, etc etc., however did not completely die. Also, pulling the plug wires off individual cylinders produces no effect and the spark is weak, leading me to believe it is currently in limp mode. However, it should still display the CEL at KOEO and should put out codes.

Hi. I spent the entire day reading and reading before deciding to register and post. The car is a 1994 LS400 with the typical hesitation, stumbling, etc etc. I used a SnapOn Solus scanner and could not retrieve any codes. Furthermore, the CEL does not illuminate at KOEO. Also, manually jumping with a wire produces no result. THe CEL comes on while running and does occasionally flicker. Underhood diagnostics: ignition coils have full and strong spark (ouch), and there is spark to all cylinders. All plugs are dirty but otherwise ok. I am ruling out a fuel or major mechanical problem because I have been doing this for long enough to know the difference. From what I have read the rough running with the CEL failure/flickering and no codes, typically indicates a bad ECU. I removed the ECU and opened it up and it looks clean but of course that doesn't mean it has not failed. I believe it needs an ECU. Just looking for some kind of confirmation from the community before I spend $200ish on a reman.