Hi this is my first post on here, originally bought my 1992 sc400 running a bit rough, rough idle and acceleration, smell of gasoline and smoke from the exhaust, but still ran and drove. Decided to go ahead and get my ecu rebuilt. In the meantime worked on fixing leaks and about a month later the ecu came back. Now i try to start the car and cranks but no start. I can hear the fuel system and start when i enter the key, tested for spark and none visible. I recently changed out the spark plugs as well. I tried to read the check engine light but instead of doing a set sequence, its non stop flashing. Anyone have ideas on what it could be? Thank you for your time.

 

ok well uhm....lets break this down. first off what was wrong that the ecu needed a rebuild? And second what condition is this vehicle in by which mileage, service history of anything noteworthy. Full disclosure I am not familiar with OBD1 in terms of diaging codes. also all i can really do is try to walk step by step and see where things went wrong from barely running to lawn ornament.

 

When you entered test mode did you use the E1 terminal and the TE1 terminal? Also you might have to reprogram the ecu after it being rebuilt.

 

I

 

i had this same exact issue when i got my SC , same scenario except i didn't do anything with my ECU. i did the fuel pump ECU mod and just kept cranking the car while holding the accelerator. 2 days later it started lol just make sure you don't flood the engine,

 

It had a really low and rough idle, about 400 rpms but even then id have to hold the gas a bit so it wouldnt stall. Heavy scent of gas while running, lag in acceleration, stalling. Im not too sure on the maintenance, does have about 288k on the dash. Previous owner had it, sold it, then bought it back. Theres been a decent amount of owners😅

 

Yes, what does reprogramming do? How can it be done?

 

ok thats a decent start. so uh....lets see. low idle barley holding itself up without throttle imput, rich exhaust fumes assuming no actual fuel leak. throttle lag, and stalling. alright. When i picked up my 96 sc400 first thing i focused on was engine. the thing ran like a tractor, ran rich, and was on like 4 cylinders cause one of the distributors wasnt workin. first objective was timing belt. I worked for toyota for a hot minute and was able to get some carfax history. In no where did I see the belt being done. mind you i picked this up in 2020 with 156k. was I right to get that first. belt was missing teeth, cracked, everything you expect from a near 25 year old belt. it jumped timing a full 180 Degrees! so that was dealt with and as i put it back together i replaced spark plugs, wires and the rotor on one of the banks. after that it sounded just a Toyota V8 should, mean. So take this from an internet stranger with 288k on yours I'd probably look at that timing belt. those should be religiously replaced every 100k or 10 years. oh and if it needs it water pump too. you wont regret it as its right there in front of ya. as for your ecu deal thats best left for someone else to answer. I am a caveman with a rock.

 

Could it be a possible misfire. I would do what @Brandon832 is stating on getting codes pulled. If it's sitting a while, drain the tank and add fresh fuel. IMO I wouldn't go straight to the ECU rebuild process, granted it might be the main culprit, because it sure wasn't my main issue I continued to have issues post rebuild. I would suggest double check your sparks and wires. Check your ECU pins to ensure none are damaged, missing or bent. Ensure all wires are properly seated, double check ignitors to ensure none have slipped out. With the rebuild ECUs sometimes it does take a few times for it to get back up and running.

 

I agree as well i have no clue with electrical knowledge, but i checked the timing belt right now and it surprisingly looks pretty good, like fresh rubber no cracks or missing teeth. Could it be the spark plug wires or distributor? When i replaced the spark plugs earlier this week i noticed the wires weren’t the best condition, some of the rubber pieces were off, one of the end tips is stuck in the hole.

 

Update: would a video of me trying to start it help?

 

i have a complete Matrix chart somewhere, that is how i ruled out some things and pin pointed the exact issue, here is a screenshot i will try to find the full chart , the numbers indicate which order you should start testing

 

hope this file helps

 

Thanks! Im following the no complete combustion since i changed the spark plugs already there has to he some. Honestly confused about the ecm power circuit, switched out the ignition coil still no start. Next should probably be either the distributor or my spark plug wires not sure.