Trouble starting, then very rough idle and backfires (Page 4/4) WingsGT FEB 26, 10:39 PM quote Originally posted by Stingray92: I would suggest starting a list of what you've confirmed to be in working order. Follow it up by what you're observing. Instant/overnight symptoms are rarely mechanical. Check for bad grounds/corroded electrical connections on the ignition system. Just as others have already stated. Kind of have a list running but could probably organize it better. I need to check the grounds more thoroughly probably, so I'll work on that as well as doing the compression test I've been trying to get to. I've checked most of the electrical connectors that I can find easily, none of them ever looked that great but I used some contact cleaner on some of them a while back and I don't see any serious corrosion on anything now. But I can go back over everything again. Are there any connections I should look at that are more difficult to reach or locate? Tested spark from the distributor and it seemed strong enough. Any way to test that more accurately? I also read ECM codes (blinking light) and it only had code 12. It sounds like that's normal when the engine isn't running and the ICM does actually work based on spark test, so if it is a bad connection somewhere else could it be something that doesn't store a code? I do hope you're right and it's not mechanical, but it seems like that also makes it harder to find. Still kind of worried it might have jumped timing, but I don't remember it running weird at all the night I parked it. Bent over another pin in my ALDL connector so I think I can connect a resistor across pins A and B now (R3 in the instruction diagram), will try to get that put together and test WinALDL again tonight or tomorrow. Patrick FEB 26, 10:52 PM quote Originally posted by WingsGT: Spark at 1/4 inch was bright blue for the most part, immediately after starting to crank I saw a little duller color but I could have grounded my wire better probably. quote Originally posted by WingsGT: Tested spark from the distributor and it seemed strong enough. Any way to test that more accurately? I don't know what to tell you. It either jumps a quarter inch or it doesn't. WingsGT FEB 27, 07:57 PM quote Originally posted by Patrick: I don't know what to tell you. It either jumps a quarter inch or it doesn't. Good enough for me then! Tried the ALDL cable with a 10k resistor added between A and B for diagnostic mode, still didn't work. This time I'm only getting one packet of data instead of periodically getting 2 like my earlier screenshot showed (red box at the top, guess it's supposed to say 20 for 20 separate data packets). Not sure if that means anything. But the data did stop when I turned the car off, so it's probably not floating values from bad wiring inside my cable. Could still be a problem with how I wired it. I'll try adding external power from the car battery instead of using the USB 5v, and if that doesn't work maybe start over with a different serial converter. But I have to go out of town for work tomorrow so that'll have to be this weekend.