BlackIRON

soo i have a 96 sc300 us spec ob2. car ran perfectly since i bought it until roughly 4 months ago. The car would randomly stall out, as in the electronics and dashboard would stay on but the motor would shut off. Now after that would happen i would try to crank it again and the motor itself will crank but not turn over and actually start. but if left untouched for anywhere from 25 mins to 4 hours when you tried again it would start but as soon as you shut it off it would need to rest again. i figured it was the fuel pump ecu, i did the mod as almost every forum has and voila, now 5 months later i had abo****ely no issues at all, now tonight on a fast food run out of nowhere it began with the same symptoms. any ideas? i am planning on checking my plugs, fuel pump, re check the fuel pump ECU, coolant temp sensor and possibly even my cam and crank sensors. i would love any advice or pointers. My only real worry is that i had replaced the factory distributor with a Cardone brand from partsgeek ( i know) and possibly now that one may be failing me but i feel it is more a fuel issue than a spark. also the only engine code i have is a bad 02 sensor and burn considrably rich.

t2d2

iTrader: (8)

I'm confused... If you did the fuel pump ECU mod, you bypassed it, so what is there with the fuel pump ECU to re-check? The only thing there would be a sporadic connection in the bypass, which seems unlikely given the symptoms which are too regular. I have a feeling we're talking about different things.

I had some start-stall problems early on with my SC400. I was doing a lot of troubleshooting at the time and don't know/recall what exactly fixed everything, but I think it went away after servicing the main ECU.

BlackIRON

i had leaking capacitors in my ECU, i replaced them, got a new fuel pump, and also did all the spark plugs and cables and re did my main grounds, also changed fuses. everything seems fine again for now has not stalled all day from 6am until now that i just got home has been good. ty for those who read anyway.

BlackIRON

well, today she ran fine and decided to never crank up again, she intermittently dies after only 3 minutes on a cold start and 45 seconds on a hot one, after that she just cranks and cranks but wont turn on, tried to check the computer and it cant communicate with it, i am swapping the ecu over the weekend and trying my luck, does anyone know a thread or if all our ECu's are interchangeable or do i need matching numbers.

1997Soarer

iTrader: (1)

I'm not sure about the matching ecu numbers... that's probably a good idea to do. That way, you get the ecu you need and know it will be 100% compatible with your car.

You said you have a 1996 SC300, so you will need an OBD2 ecu for sure. And it will have to be from a donor car that has the same trans as you.

But, what I'm not quite sure about is, if you HAVE to have a 96 ecu, or if you can use a 97 as well.

I know there were some changes in the cars between 96 and 97 beyond the bumpers, such as the gauge cluster and ABS system. I don't know if these changes are different enough that the ecu is different between the 2 years. You might want to try searching in here and seeing if anyone has ever compared a 96 ecu to a 97

GS250

Hi, how did you find out that you have a leaking capacitor in the ECU? any error code or symptoms?

GS250

has the ignition coil been looked at already?

t2d2

iTrader: (8)

Partial ECU list: https://www.clublexus.com/forums/per...s-by-year.html

BlackIRON

my current ecu has one very small capacitor and under it is a small leak, i soldered it possibly incorrectly or not well enough and the problem persists, new board comes saturday but when my car refuses to turn over it still has spark and fuel pressure just no communication with the ecu via obd2, tried a reset today and driver footwell fuses, i spent a good chunk of cash on the parts lol, next up is sensor by sensor, this 96 has one ignition coil and a cap and rotor, i have the oem coil and replaced the distributor. i tried an advance auto one and had the same effect when the car quit eventually it wouldnt turn back on

EDIT: t2, my ecu aint on that list 89661-24460

t2d2

iTrader: (8)

Post in that thread so your info can be filled in to help others.

BlackIRON

got another 96's ECU and the car stopped stalling but now has codes p0120 TPS "A" circuit problem p1400 sub throttle position sensor circuit fault and p1401 sub throttle position sensor circuit range/ performance and i also now have my trac light on 24/7 whenever the motor is on which i did not before with my original ECU. any ideas or input?