Alright I've been struggling with this for weeks now. First really cold day of the year (below 50), go out to start the SC and the idle is low, after taking quite some time to finally turn over. Let it warm up, let the coolant temp get about halfway and start my drive to work. Immediately I notice there is extremely low torque like basically none, its struggling to get up to speed even like 40-50 MPH. Tachometer works proper up to like 1.5-1.7k, then DROPS straight to zero when reaching around 2k RPM. Engine still revs even though the tach is dropping. Then I noticed while driving that it reeks of gas, like its running rich. The exhaust is straight piped so its loud anyway, but it's significantly more loud and chuggy, sounds like a cammed V8. Has driven perfect everyday I've owned it until this rough cold start.

Take it in to the shop I work at, start checking stuff. Ordered an OBD1 scanner, check the codes, even though there is no check engine light. Absolutely no codes. Thought of a mass air flow sensor, maybe the engine is not breathing/getting correct air/fuel mixture (would explain low torque and lean fuel smell) so unplugged that. Idle got worse and check engine light came on so I know the signal wire for the CEL is good. Plug it back in, idle gets better but is still horrible compared to how it normally runs. Replaced the green plug engine coolant temperature sensor sticking out upright on the passenger side of
the water bridge(not the one for the gauge), passenger side coil pack, and the cold start time switch for the cold start injector.

No change in the rich fuel smell or way the vehicle is running. Throttle body is not stuck closed. Inner throttle door is open at idle at like 1-2% and outer door is halfway open. Pulled my ECU for the first time since purchasing, it looks like it has had some repairs done to it but was not repaired very well. Doesn't look super horrible though. Before I dump even more money into the wrong parts, anybody have any ideas? Would be very grateful to anyone who could help, thanks.

 

Given the known issues with ecus on these cars and that you are unaware of who/what was done on the ecu, I lean toward that. Classic symptoms you describe, so again, makes me lean toward the ecu. Do you have one you can borrow to try out? I have several 2j ecus, but nothing for your 1uz.

 

Unfortunately I have not gotten to the point where I have some spare ECUs lying around. But that was going to be one of my next paths to go down unfortunately. I've looked at standalones for the SC400 and I cant really find any company who makes one, remanufactured OEM ECU from Flagship is like 800 dollars. I really wanted it to be cold start injector related just because it sounded like it fit all my symptoms so well lol, but I think I've almost let that cloud my judgement throughout this diag.

 

When you unplugged the MAF did the performance return? i understand it idle bad but what about everything else? also with the car off unplug the passenger side coil that you replaced then try to turn car on if it doesnt start and run on 4 cylinders the driverside coil is bad. usually the driverside is the one thats goes bad first.

also when you have the off and turned to power ACC does the engine light come on?

 

Performance remained the same when MAF was unplugged, weird, low and chuggy exhaust noise, super rich fuel smell, low torque/acceleration and tachometer dropping like its not reading past 1.6-1.7k RPMs. CEL does come on when the key is turned to ACC. I will do what you said though SexCoupe,with the coil pack and update the thread afterwards.

 

Also do you recommend unplugging the pigtail to the coil or unplugging the coil wire from the distributor cap, SexCoupe? I just wanna make sure I'm doing it how you think I should.

 

either way is fine but best to unplug the connector/pigtail.

 

Thank you sir. Will update after I try this. And thanks to everyone replying to this past present and future, I'm starting to hate my life with no V8 brap, lol.

 

SexCoupe you are the man. Driver side coil was cracked. I feel like such an idiot lol. Back to full power again, running like a dream. Thank you everyone who replied, hope this helps someone else too.

 

No problem glad you are back rolling