blackdemon_tt
Member
Hello All,
I have a 93 SC400 pristine condition and 132k on the clock, dealer maintained with records. Ok I've been trying to work on some issues. for example a bouncy idle or surge idle. An extremely low idle at initial cold start and as well as hot start. I started my journey by bypassing the fuel ECU as I was stalling below 40mph. If I let it coast at speed the RPM would drop like a rock and would stall shortly after, but would come back to life if I hit the gas, but this was intermittent or 50/50. So, this led me to bypass it.. About a month passed by and the stalling was pretty much gone, but the low idle was now more common as it would often idle so low it would just stall out. So, I gave it the benefit of the doubt and continued driving it, until it stalled out 3 times in a half mile. At this point I replaced the fuel pump relay and it appeared to be good to go for about 2 months. No stalling, no hard start, no low idle. Yesterday driving home from work, I made a stop to run an errand and it would start. It would turn over, but would not start whatsoever.... So I popped the hood and started looking at the engine like a monkey would a wrench. I disconnected the battery, pushed in connectors, went over spark plug wires and pulled and reseated on each spark., and replaced the big green relay while I was there.. Not really knowing what was up I reconnected the battery and tried starting it.. and it started, but with a very low idle... so I'm looking for guidance at this point and time... I haven't probed the power from the ECM to the fuel pump yet, but I will likely do that this week, as my schedule is slightly crammed...
TLDR:
low idle and multiple stalls,
Replaced, fuel relay, Green relay, bypassed fuel ECU,
No apparent issues after a month, but then after a 30 minute drive, car refuses to start. Disconnected the battery and reconnected it 15 minutes later, started fine, but low idle continues.... pondering probing power from the ECM to Fuel pump and vice versa... any guidance is appreciated.
I have a 93 SC400 pristine condition and 132k on the clock, dealer maintained with records. Ok I've been trying to work on some issues. for example a bouncy idle or surge idle. An extremely low idle at initial cold start and as well as hot start. I started my journey by bypassing the fuel ECU as I was stalling below 40mph. If I let it coast at speed the RPM would drop like a rock and would stall shortly after, but would come back to life if I hit the gas, but this was intermittent or 50/50. So, this led me to bypass it.. About a month passed by and the stalling was pretty much gone, but the low idle was now more common as it would often idle so low it would just stall out. So, I gave it the benefit of the doubt and continued driving it, until it stalled out 3 times in a half mile. At this point I replaced the fuel pump relay and it appeared to be good to go for about 2 months. No stalling, no hard start, no low idle. Yesterday driving home from work, I made a stop to run an errand and it would start. It would turn over, but would not start whatsoever.... So I popped the hood and started looking at the engine like a monkey would a wrench. I disconnected the battery, pushed in connectors, went over spark plug wires and pulled and reseated on each spark., and replaced the big green relay while I was there.. Not really knowing what was up I reconnected the battery and tried starting it.. and it started, but with a very low idle... so I'm looking for guidance at this point and time... I haven't probed the power from the ECM to the fuel pump yet, but I will likely do that this week, as my schedule is slightly crammed...
TLDR:
low idle and multiple stalls,
Replaced, fuel relay, Green relay, bypassed fuel ECU,
No apparent issues after a month, but then after a 30 minute drive, car refuses to start. Disconnected the battery and reconnected it 15 minutes later, started fine, but low idle continues.... pondering probing power from the ECM to Fuel pump and vice versa... any guidance is appreciated.
