I've looked through several threads today and have done a lot of research on Cali SC300 ECU part numbers.

I am strongly suspecting my ECU may need capacitor repair and I just want to throw out my symptoms before I pull it and send it to Tanin for repair.

--
Basically, as of today or perhaps as early as last night, every single time the car is started it is extremely rough, as if timing is off or a spark plug has gone bad or coolant has gotten into the spark plug galley. Tonight it even got a bit worse by not firing right up as always.

But either on its own or by revving slightly, the start idle clears right up. The driveability is also always 100% fine. It's just at startup there is this issue. Normal idle might be 100rpm too low occasionally but I doubt it. Hard to tell from the factory tach. It's never an issue.
--

My 1993 SC has 237k miles. It's an original Cali M/T car.

I have no spare NA ecu and I've been looking on ebay with no luck. I do have a Supra TT 6-speed OBD1 ECU but that won't help for now.

Anyway, does this sound right to you guys? Failing ECU capacitors? The symptom has come on so suddenly.

And my final questions, since I'm in a bind and need a spare ECU asap:

I assume that using a Federal ECU would only result in a CEL light and not any major drivability issues, correct?

Would my car be drivable at all with any OBD1 A/T ECU and would it even idle correctly?

Thanks, everyone!

Edit/Update Feb 5th, 2016: A few issues were involved here and MOST of them were solved by page 7.

Namely:

1) ECU needed capacitor & injector driver service -- I did this but Fedex lost my ECU and I had to replace it with another identical one

2) Spark Plugs, Cap & rotor and plug wires replaced (premature wear at 13k miles but older wires)

3) Original injectors replaced with remanufactured injectors

4) Idle Air Control Valve engine harness connector replaced (possibly unrelated)

5) ECU Coolant Temperature sensor was failing -- replaced with OEM

6) Original 2JZ-GE Distributor assembly was replaced with a new OEM unit from Japan (very likely not part of the issue but was a possible suspect while servicing/replacing ECU)

Edit/Update Feb 14th, 2016:

See post #102. The main issues that prompted this thread were solved by the fixes listed above but they did not totally cure the initial rough cold start idle. Still investigating...

Edit/Update March 5th, 2016 (Edited March 22nd, 2016):

See Page 9, Post #130

After all six items listed above, plus a seventh, replacing the Idle Air Control Valve with a Standard Motor Products AC425 variant of the OEM part (cleaning the original IACV might have done the same thing) the issue ALMOST seemed cured but the rough cold start idle is still present.

Additionally, a Code 71 EGR condition has showed up. Testing with another EGR VSV, cleaning the intake plenum and EGR port and possibly replacing the EGR valve if found to be faulty.

Update/Edit March 22nd, 2016:

For the diagnosis and final curing of the CEL Code 71 (EGR System), refer to page 10 of this thread.

That entailed all of the following that had to be addressed:

--clogged intake plenum EGR passage
--clogged EGR valve port-to-vacuum-modulator
--bad EGR vacuum modulator
--bad EGR VSV
--carbon buildup (but not clogging) in the EGR valve and EGR pipe. EGR valve diaphragm and piston were working fine.
--probably a couple of vacuum hoses to the modulator that weren't sealing

Finally, after performing the TSRM test procedure on the TPS sensor I've determined that one of its circuits is failing or has gone bad, although there is no CEL code for it yet. That will be replaced.

Update/Edit April 6, 2016:

Refer to Page 11, posts #159 and #160.

-Initial rough cold start idle eliminated after installed a new OEM fuel filter and a new OEM TPS sensor, plus an ECU reset after confirming the TPS adjustment.

-Replaced confirmed faulty EGR temperature sensor with a new OEM unit (aftermarket versions do exist). Performed ECU reset. No CEL after 38 miles so far.

-Hesitation linked to another prematurely distributor rotor (replaced with a new OEM) and very likely inferior or prematurely worn spark plugs again. Plug 5mm silicone plug wires last used by mechanic were not Denso brand or from Toyota.

--Replacing spark plugs with Denso PK16R11's and new Denso OEM plug wires, plus a new cap and rotor.


Update April 9th, 2016:

Frustration in the extreme...

CEL Code 71 came back again 91 miles after the last ECU reset (which accompanied replacing the EGR temp sensor with a new one).

Double checked the used replacement EGR VSV and it holds pressure and the solenoid works with direct +12V and Ground.

There is nothing left to replace in the EGR system.

This points directly to using a specialized bendable cleaning tool at the end of a variable speed drill to clean the intake manifold EGR port even more thoroughly than it was cleaned before. Plenty of work ahead all over again.

Cumulative Update May 31, 2016 (Mostly solved) -- Refer to Page 17, post #246:

--EGR "Y" Manifold replaced with brand new dealer part. This solved the CEL 71 issue. Attempted to find suitable freeze plug replacement for original Y manifold. Will pursue that cleaning and replacement as a DIY at a later time (off the vehicle).

--Replaced Fuel Pressure Regulator with new factory part

--Switched back to Tanin Auto repaired 1992 M/T Cali-Spec ECU, send 92-94 Toyota/Lexus Reman M/T Cali-Spec ECU to Tanin for repair

--Replaced Rear catalytic convertor with a new Catco #66266 "Direct Fit" (Catco has replaced their old 66266 stock with a new #93266 model)

--Replaced Front OEM catalytic convertor with brand new OEM front catalytic convertor. Manual smog dyno test showed extremely passable emission numbers. Determined that intermittent rich running and overfueling conditions had gradually fouled the primary catalytic convertor after only six years of use.

--Passed STAR Test Only smog requirement with flying colors on May 31, 2016

Edit/Update 27-28 November 2016:

--Refer to Post #267 on Page 18. Replacing the original 24 year old fuel pump with a brand new Denso OEM replacement seemed to have cured the rough start condition... but it ultimately did not. The car does idle and run smoother as a result. My SC's original fuel pump was probably getting a bit old anyway and it could have been progressively getting weaker after 24 years but ultimately replacing it with a new one did not cure the intermittent rough cold start issue that began in roughly November of last year and is still ongoing. My Fuel ECU is still not at fault to the best of my knowledge because the Fp & +B bypass test results in no change to fuel system behavior and I have had no other symptoms that would directly suggest the Fuel ECU is at fault.

As of this update all other issues in this thread have been corrected except for this one.

Update late January 2017:

--On a hunch that I may have been getting weak spark I also replaced the 24 year old factory igniter. The occasional rough idle start was still not eliminated, however the engine response seemed to be better than before.

 

it could be related to the ecu but I am not sure those symptoms are a 100% sure fit. it also sounds like it could be a leaky injector or even a distributor issue. if you had the capacitor issue I think it would not clear up and continue as you drive etc.. show up as misfires, generally speaking the hotter the caps get from operation the worse it will be when they are bad. a leaky injector usually causes a rough start that clears out, how bad the start is directly related to how long you leave the car sitting (more time for the fuel to leak in and sit on the cylinder top). maybe try some injector cleaner and see if it helps out.

 

Thanks Ali. I'm checking the injectors tonight with a stethoscope and I'll give some fuel injector cleaner a try. (wish I hadn't just filled up the tank though).

If the injectors are the real issue, worst case, RC Engineering is nearby in Torrance.

You're right: every time this happens the car clears up fairly quickly and it does not begin to drive worse than before after reaching operating temperature.

Forgive my ignorance about this. Injector diagnosis is something I've not learned much about until now.

 

Tonight while on some errands I went to a Pepboys and bought some Techron to put in the tank. The SC still consistently had its starting and rough idle issue but it always cleared up after about 20 seconds to 50 seconds.

Drivability was fine.

After I finished my Pioneer sub-amp replacement project I decided to give it a driving test.

Starting was even worse than before, hiccuping before finally kicking over. Rough idle as before but this time with a LOT of white smoke. The idle evened out, finally, but the smoke did not.

I took it up the street and around the block and called it quits. I'm taking it into my mechanic first thing in the morning.

I did try to listen to the injectors with my stethoscope but the rough idle always cleared up before I could accurately put the needle onto them. This last time I cut the stethoscope test short due to the smoke.

I'll note that there was NO smoke after putting Techron in, driving around to several places and multiple starts and stops of the engine. This only happened after parking and leaving the car off for several hours.

Drivability this last run was still fine just as before, however. Other than the smoke.

And I do believe it to be consistent that the longer I left the car off, the greater the chance of a rough idle start or stuttering start. If I had the car running, shut it off and almost immediately turned it back on within seconds, the startup would be *almost* normal. Most of the time, that was the only marginal exception in behavior.

Ali, I'm sure you're right that I have a bad injector condition. I'm not ruling out my spare ECU search just in case that does turn out to be the issue.

I will have them check the distributor as well.

Thanks for your help! I'll let you know what the diagnosis is tomorrow.

 

After the car sits over night, pull the spark plugs and see if any coolant is sitting on the cylinder.

When the HG went on my car, cold starts were an issue. The HG didn't just "pop", it gradually got worse and worse and the cold start issue was a result of the HG seeping coolant into the cylinder and blowing out the spark. You could hear that the starter sound was different and not as quick as it should be. Once it fired it the engine would missfire and then chug chug until it cleared which usually followed with white smoke and then it would stop.

Compression test still came back normal, I ruled out HG unknowingly because of this until the radiator / coolant issues showed.

Other symptoms included:
- Hiccup misfire in exhaust at idle
- Bubbling radiator
- Losing coolant, having to constantly top it off
- Milkshaked brown coolant
- Cold start issues
- Coolant / water in cylinders after sitting
- White / grayish smoke
- Slight overheating



Hopefully this isn't the issue, just throwing this out there. What color is the smoke you are seeing? If it's white / gray it's possible the ECU could be dumping fuel.

These cars are tanks, it's amazing what we put them through and they just keep on!

 

yeah as I said I wouldn't rule out the ecu by any means it has a few of the right symptoms but definately add the injectors to the list and also the headgasket as HiPSI said, it does happen from time to time.

 

Guys, thank you for throwing all the possibilities on the table. A head gasket issue is about the last thing I need right now. If I did have to get as involved as a head gasket I still can't use the GTE parts I have.

I was going to take the car in this morning but now I'm paranoid about checking the cylinders before driving it.

The smoke is definitely white/gray and the exhaust smelled rich last night. Have't driven it since. That was a first (the heavy smoke). I have not had any signs of overheating.

Also, I just had a Blackstone oil test come back and there were no trace signs of coolant contamination detected in the oil. I guess it's possible I could have developed a HG issue right after analyzing my oil but so say the results it was clear of any coolant only a few hundred miles ago.

These symptoms just developed so very suddenly and without warning or other abnormalities.

Could a leaking injector condition produce this smoke? We know the ECU is a possibility still.

I am going to hold off on driving the very short distance to the shop if what I need to do is check the cylinders for coolant while the engine is cold.

Thanks guys. Pretty frustrated right now.

 

Kahn, there are about a half dozen different ways the headgasket can go, if you just have a tear on a cooling passage it can leak into the cylinder but not contaminate the oil. eventually it will get worse and leak more places and show up in the oil if that is the case, probably have overheating by then. some mix with the oil right away, others only show up on a coolant system leakdown test.

the leaky injector can cause the smoke in the same way the bad ecu does, its just overfueling and can be the injector leaking, the wiring shorting out (make sure all your injector clips are good no broken tabs and clicked into place, listen for the click, no click = unplug and clean connector surfaces and try again), or the ecu caps messed up causing the injector to stay on too long.

I think Hi psi was on the right track, let it sit for a while and then pull the plugs and shine a light down there, if you have enough fuel leaking from the injector you should see a puddle in there on a good motor the piston rings will not let it seep down into the oil pan, which causes the whole rough start issue. you will also see if you have coolant puddled in there but it will be hard to tell the difference between the 2. also since you have the stock intake its a terribly annoying task of removing the intake just to do that but you can check the front 2 cylinders without doing much and maybe you might get lucky.

you wont be able to hear a bad injector always. sometimes they just leak when they are off and work fine when they are running.
our cars are designed to have pressure in the rail when its on, and then when you turn it off the pressure stays in the rail and the injectors for the next startup.
if you have a leaky injector, all that pressure causes it to push out all the fuel in the rail into that cylinder while it sits, the longer it sits the more fuel leaks in.
this fuel is not combusted really cause there is so much the plug does not fire and is "wet" so all that raw fuel gets pushed out into the exhaust and catylitic converter.
then the cylinder will start combusting after the plug sort of dries off (hence the hard start where it feels like its a cylinder down or so), and then when the exhaust heats up, it starts to burn up that fuel sitting in the exhaust and right on top of the cat, and after enough times it will melt right through the cats, so its good to sort out fueling problems sooner than later.
not trying to scare you lol, but raw fuel in exhaust it the number one ruiner of catalytic converters, otherwise they generally last the life of the vehicle.

If you didn't say it smelt like fuel, I would have said you could have had a valve stem seal go bad, which lets oil burn off and is also sort of white.
coolant will smell sweet, I know sweet is more of a taste than a smell generally but that is the best way to describe it.

it might take less time to open up the ecu and have a look at the capacitors, then you can rule that out.
you can use an auto ecu also, since your car is an original 5 speed there are no wiring changes needed just push the clutch in to start (wired like a neural park is from factory) unless you have it bypassed already.

I wouldn't necessarily be afraid to drive it, but if its really excess fuel then just minimize it cause of the cats and change the oil earlier than normal, the fuel will degrade regular oil and thats about the only way it can hurt the engine. I have done all sorts of things to mine and its still fine, so dont sweat it its a 2jz it will be fine if all the pistons are still inside the cylinders =)

 

Ali,

Thank you. That's a lot to chew on. And I understand that a constant fuel flooding condition can lead to catalytic convertor failure. Which I definitely do not want, especially with these hard to come by versions :/

Here's where I'm at so far:

-Scheduled to bring my car in to my mechanic's at 8:30AM tomorrow. It's only a few blocks away so here's hoping that won't be too bad.

-my mechanic pretty much agreed with all the possible culprits you and HiPSI mentioned without my saying much beyond my symptoms. He also suspects the injectors.

-I did pull my spark plugs #1 and #2 and visually checked inside the cylinders. There was zero coolant in the plug galley there and those two cylinders were dry inside. The plug wires have endured one plug change before the last one and after inspecting them at that previous time I figured they'd be good until 120k or whenever they needed to come out for any other reason. Since I'm pretty sure the injectors will be checked I will probably replace them with this service.

-I got to the ECU and removed it. Now at least I know what I have for a 1993 Cali M/T: xxxxx-24321

-Unfortunately here is where I'm reluctant to go forward to open up the ECU. Same as with my 2JZGTE ECU I noticed the cover screws are practically seized on and they appear to be very easy to strip. I haven't opened up the GTE computer for inspection for that reason and I'm afraid to screw this one up in the same way.

So I'm going to button up the car and definitely get a spare ECU. I will just take mine back out and send it to Tanin as soon as I can. But if the ECU is the problem after all then I just won't be driving after I take the car to my mechanic until I have it replaced.

I just wish there had been any measure of warning signs beyond the first 24 hours.

 

Friday I dropped my car off to my mechanic so that he could diagnose the car when fully cold.

He was done with it by Saturday afternoon. After only 13k miles the spark plugs and rotor were worn out. The cap was so-so but we replaced it anyway. The plug wires I had reused during the last spark plug change since they seemed to be in good shape at that time, however they were worn by now and we replaced those as well.

That's not many miles on the plugs. I did drive cross country on them with a lot of added weight in the car. Perhaps the strain on the engine accelerated their wear but I don't think that was the only cause.

For my mechanic the rough start and idle issue did not persist after the service. He was able to observe those symptoms before he performed any service, however. It was fine for me when I picked it up yesterday. As before, drivability has always been normal despite the issues.

Saturday evening, however, I had to run an errand and the starting issue, rough idle and *initial* white/rich fumes persisted though the smoke did not resurface after I took the car onto the highway and my idle was mostly ok thereafter.

So whatever the problem really is, it probably had a hand in prematurely wearing out my plugs, cap and rotor. Tomorrow the spare ECU comes in and I will swap that in and send my original ECU to Tanin for preventative (or necessary as the case may be) service. Hopefully that will prove to be the issue.

If not... then it's on to investigating the injectors. However, my mechanic did check all the cylinders visually during the spark plug change and he saw NO oil or fuel contamination in any cylinder.

 

Update today:

Some progress! But I don't think I've quite solved it yet. I swapped out my original '93 M/T Cali ECU for the '95 M/T Cali ECU.

First thing I notice is that starting was instantly better and almost completely normal. Before, there almost always would be a stuttering start. However, while the first second or two had the rough cold start idle, it cleared up and warmed up normally. There was no rich smelling white smoke this time either.

The one caveat was that I've definitely confirmed a '95 Cali ECU into a '93 Cali SC results in a permanent check engine light. Drivability is perfectly good though. I could be mistaken but I believe this might be related to 1995+ SC's getting heated O2 sensors... which my car lacks.

I drove around, took it on the highway and parked, shut down and restarted multiple times. No more smoking but the initial rough idle (albeit very diminished after the plug/wires/cap/rotor tune up) is still present just after start up. But this goes away and does not return.

So I know this for sure:

1) The spark plug tuneup helped tremendously, but the 13k lifespan of the old plugs and rotor are perplexing

2) The 1995 ECU, while throwing a CEL due to being too new for the car, SEEMS to have cured the startup hesitation

3) I am going to send my '93 ECU to Tanin to get serviced regardless and will reinstall it after.

4) I should look into the injectors next, even though my mechanic found no evidence of fuel pooling in the cylinders.

My thoughts on injectors are this: I may look to buying a set of used SC-specific #23209-46031 330cc Densos to have cleaned and balanced and waiting to swap into the car with all new upper and lower O-rings.

Or is buying used injectors of questionable condition a poor idea? I'm not looking forward to buying brand new injectors right now as the cheapest I've found a new set for is $145 each. That's almost $900 just for those alone.

I also did try again with loosening the screws on the old ECU (WD40 and careful tapping) and got it open without issue. I did not take the circuit boards out but with a flashlight I could not immediately see any board damage or capacitor bulging. This might not mean there isn't any but I just couldn't see the evidence myself.

Perhaps not enough info to go on but what do you guys think so far?

Edit: At this point I am also going to give Seafoam a try. Is there any big difference between the traditional "Seafoam Motor Treatment" can with the prominent red label and "Seafoam Top Engine Cleaner and Lube"?. Not sure if there is much of a difference other than that it seems one goes into the intake and the other goes into the gas tank.

 

This was an interesting read with mostly related symptoms.

http://www.askamechanic.info/askamec...t/view/111/47/

 

I confirmed pretty much the same thing recently... Putting a '95 SC400 ECU into my '94 SC400 resulted in the CEL, but for EGR, which I believe went to a more complicated and tougher to silence system in '95. I didn't have any O2 codes, though, unless the SC300 and SC400 got different treatment in '95? The other thing I got was the O/D OFF light flashing, which wouldn't be applicable to you with a 5-spd.

You can buy a cleaned and flow tested set of OEM injectors on eBay for under $100.

 

^^ So you've discovered the same thing for SC400's either with the O2 sensors or EGR system starting in '95. Interesting. Honestly I couldn't tell you what code my CEL represents. I haven't tried testing it since I have a pretty good guess it's just the wrong ECU for the car and operation (my original issue aside) is normal.

All right. I am going to pick up a set of Densos with the same part number my car corresponds to. I just wasn't sure how safe this was. I've already found a set of original remanufactured/flowed Densos on ebay for $150. I think I'll just go with those.

This is beginning to add up but perhaps 237k on original injectors is a bit much anyway.

 

I actually switched back to the '95 ECU yesterday, having taken it out after that experiment, because my "low mileage" cold start injector I tried out with the manifold porting project doesn't seem to be working at all, and it was easier to temporarily swap ECUs (no CSI in '95) and deal with the two warning lights than to pull the plenum off again, spill fuel, get new crush washers...

As for eBay injectors, you're paying for a service more than a product, so the typical "Chinese junk" image of the auto parts there isn't coming into play unless someone is willing to risk their seller reputation by carrying knockoffs. (I've bought from seller 'eazeefind' somewhere near you in CA, but you'd have to check if they carry SC300 injectors that aren't listed.) And keep in mind, our favorite ECU rebuilders do business on eBay.