I knew the next thing would come, and it has. Sorry if this is lengthy, but I like to be thorough. My newish-to-me 1998 ls400 has exhibited some odd electrical and running issues. For 3 weeks it refused to start, acted like it had a dead battery. I have 2 batteries, both from 2018, one came with the car and is from Toyota and I have a Lexus oem battery for my other LS400. Neither battery would start the car, so I cleaned the negative battery terminal and replaced the thoroughly corroded positive terminal. No change. I checked fuses and stuff, everything seemed fine. Then I went on vacation to Miami for a week, took a break from the non-starting LS, and earlier this week it decided to start up no problems after being disconnected from the battery for 2 weeks. All was well for a few days, then last night after wiping down the engine bay with some degreaser on a microfiber towel and dressing the Underhood bits with mothers back to black, the car started up with a nasty misfire. The CEL didnt come on for about 5 minutes, and it indicated a misfire on cylinder 6. Checked the coil connector, clean and dry. Let it sit overnight and it started smoothly this morning. On my short drive to work (5 minutes) it began to misfire at a stop light. NO CEL this time, just an intermittent loss of smoothness and idle dropping to 400ish. It only misfired a few times, and only stopped while idling. The radio also cut out for a second, which doesn’t seem misfire related. After work, I let the car idle in my driveway for 10 minutes and it refused to misfire, but it did randomly shut off, as if the key had been removed, but all electronics stayed on. Still no CEL, but it did the same thing the day I got it started as I was topping off and bleeding the coolant, and the CEL did come on; communication interference with the engine immobilizer. That was a weird one, and I did not know what to think of itStarted fine afterward, and i replaced my key fob battery just to rule that out (although my understanding is it uses RFID and the fob battery has nothing to do with that) The door locks also acted funny today, as I was fiddling and testing stuff. What all this adds up to is most likely a failed ecu, so I tore apart my glovebox and fished it out.
That shit is not fun yo. I’ll obviously be checking my spark plugs (of unknown age and mileage) and checking the resistance of the coil packs, but I feel like my car has the infamous failing ecu capacitors that plague even a car that can go 1,000,000 miles (Matt Farah’s is a 96 but basically same thing). The lack of a check engine light just makes no sense to me. Im gonna open up the ecu and inspect it for leakage, if any of you oppos have any tips or troubleshooting ideas im all ears and would love to hear them. Im really glad I have my rusty but trusty 97 LS to drive in the meantime. I might also be getting a job at my local Lexus dealer! So one way or another I’ll get this boat purring like a jaguar. Keep on keepin on y’all!