Ok, so about a week ago my 92 sc300 stalled..
I was driving normally and the check engine light blinked on and then off.
Then maybe 1 minute later down the road I was juicing it and it felt like I hit a rev limiter at ~4,200 RPM and the check engine light came on again, so I let off the gas, shifted to fifth and kind of coasted at ~50 mph.
I get to a stop light, then the light turns green and I pull away normally, but the car again feels like it hits a rev limiter, this time at ~2,700 rpm, when it does this it kind of kicks and feels like I wasn't getting any spark/ignition for one or two revs, it was real quick and then back to normal revving/driving. It started kicking and kicking more frequently so I let off the gas, turned the hazards on, and pulled on to a side road and let it coast in neutral until I roll to a safe spot to stop off the main road. When I went to turn the car off it had died. I had it towed back to the house from there.

About a week before that I had replaced the o-ring seals on the distributor and noticed my rotor was looking rather worn. So I assumed that my problems above were caused by a worn cap and rotor on the distributor. I ordered a new cap and rotor along with some other miscellaneous parts.

Before the new cap an rotor came I was able to start it on two different occasions to move it from curb, to driveway, to garage, etc.
Today the new distributor rotor, and cap came in the mail.
It was on the curb so I went to start it and it wouldn't start the first time. I waited 5 minutes an it started and I got it in the garage.
Replaced the cap and rotor, washed the car started quite a few times when the new cap and rotor were installed because I had to get it in the driveway to wash then back in the garage to do some detailing.
Decided I wanted to drive it so once I was done detailing. It had gotten a lot colder since the last time I started the car, like a ~20 degree drop from mid 70's to upper 40's.. I tried to start the car and nothing, no noise, not a sound at all. Tried to start the car a couple other times. The second time it was getting ignition and I could hear the starter motor doing it's thing, but the engine nver turned over.
3rd time I tried to start it the car started and there was a weird fluctuation in rpm from ~1,500rpm - ~1,200 rpm. So I put it in reverse and slowly let off the clutch to see what would happen, car started backing out like normal but it was like it wasn't getting any gas even though i was feathering the gas pedal and it died like I hadn't touched the gas at all.
Tried to start it two more times and both times the starter motor was doing it's thing but the engine never turned over.
So I pushed it back into the garage and that was 7 minutes ago an here I am.

What do you guys think might be causing this and are some things I should be investigating further to see if they are the culprit?

Fuel Pump?
Fuel Pump ECU?
Ignition Coil?

I don't know but I'd much rather do it myself than take it to a shop so long as I have the time.

 

First thing I'd do is check for codes. There should be some stored, if the battery hasn't become disconnected since the incident and there are no codes, then I'd pop the ecu open and look for problem signs.

Second thing I'd do is bypass the fuel pump ecu.

 

Well last time the car was running it wasn't throwing any codes. I'll see if I can borrow an OBD1 reader and see if there are any stored. Battery hasn't been disconnected/discharged so if there are any they should still be stored.

I have no idea what to look for to see if an ECU looks good or bad. I'll see if I can find some pictures online of what a good ECU looks like than open mine up and compare tomorrow. I'll also pop the back seats out and whip out my soldering (sautering? how is this normally spelled?) gun to either see that the previous owner did the 12v Fuel Pump ECU mod, or if it wasn't done I'll do it myself tomorrow.

Also will the 12v Fuel Pump ECU Mod have an affect on my gas mileage? Stock under the hood.

 

sounds like the fuel pump ecu. try the 12v mod codes for the will often not get stored by the main ecu.
12v mod won't affect your mileage at all, it just increases flow through the rail and the extra gets returned by the regulator. in stock form its got enough extra room to not be too much fuel for the regulator, so you can do the mod and the only bad things are you loose the safety cutoff from the fuel pump ecu and the extra fuel just gets heated up as its returned to the tank. ideally you want to heat your fuel as little as possible but its not that big of a deal really. you can always get another one once you figure out that is the issue or bypass it a different way. I had done it once the way in the thread but didn't like how the pump stayed on whenever the key was turned.

 

As mentioned above I would say it is your fuel pump ecu also. My Buddy's 94 SC300 did the same thing you described and we did the bypass mod good as new now. Good luck, hope that is all it is.

 

kk
I don't want to work on my car today because it snowed last night and is ~27 degrees, but I might go out there anyways just to get it started again and know what it was.

 

Ok, so I did the 12v fuel pump mod.
Car starts... sometimes, but still has the same issues.

Revved the car, and once it hits ~4,000 rpm's it misfires and check engine light pops on.
After that the car alternates idling from 1,500 to 1,100 rpm's.
It does this over and over again and sounds like it;s going to die, I just turned the car off instead of waiting to see when it would die. Also I had a friend with me, after I did the 12v fuel mod he said he could hear the fuel pump working when the key was on accessory but it was having trouble obvsiously keeping up with demand past ~4,000 rpm's and I'm thinking I need a new fuel pump.

any other advice here? Gonna order a new fuel pump and just book a flight home instead of driving like I intended too. Anything I should be looking at past the fuel pump itself?

 

Could a dirty MAF be causing my problem?
I have an oiled K and N intake, and it may be possible that the oil from the intake got on the reflective foil of the MAF and maybe I'm getting a bad fuel/air mix. When the car does turn over it does seem to be running rich, and it also would explain the sudden loss of power right around 4k RPM's.

Once all this snow disappears I'll go buy some compressed air and see if I can use that and some contact cleaner to clean my MAF. Also ordered a Blitz Air filter just so I don't have to deal with more oil causing the same problem if this is indeed my problem.

I also didn't order a fuel pump because I'm unsure of which pump I might need and which ones are better/worse. There's a lot of conflicting information and most of it seems to apply to FI applications and this car won't see a turbo for a while if it ever does. If I were to replace my fuel pump, which one would you guys suggest?

 

Back at my house today and workin on the SC.

Blitz Air Filter showed up while I was at my parents house, replaced my dirty oiled K and N air filter.
I just finished following the steps on post #23 of this thread for cleaning the MAF.
I'll check back tomorrow once it finishes drying and I'll let everyone know whether it worked or not.
https://www.clublexus.com/forums/per...rywhere-2.html
I would just like to add on the two sensors on either side that the mirror is on the bottom, not the back, and thats the only part that needs to be cleaned. I can definitely see a difference between both sides after cleaning but I'm not gonna rush it and won't try to start it until tomorrow.
This is only an issue on the 92-95 sc300, not sure how the 400 MAF is, but just more info out there i guess.

Also another useful resource for anyone who has issues getting past 4k rpm is this guide.
http://97supraturbo.com/Supra%20Scan...iagnostics.pdf
Just ctrl+f "4,000", and it touches on pretty much every part that might have issues past 4k rpm when the vvt kicks in.

MAF
-possible short in ECU
Heated O2 sensor
-Fuel pump, Fuel pump ECU, fuel line pressure, or injector blockage if car running rich as well
-Injector Leak, or Engine coolant temp sensor malfunction if running lean as well
Temp Sensor on Exhaust Gas Recirculation Valve
-Could also be caused by a short in the ECU

This guide is pretty sweet and combined with this guide for reading engine codes on my OBD1 92 SC300 I should be able to narrow this down if the MAF doesn't get it.
http://www.lexls.com/tutorials/intro/codereading.html

 

what codes are you getting. sc400 early maf's are the same type and have the same problem with oiling also.
Good luck with that maf cleaning, I think I was able to revive that maf in the end (my first SN on CL was SCfrogger), but it put up a massive fight it didn't work the first couple rounds of cleaning.

let us know how it goes or what codes you are getting after.

 

Sounds like my car when the fuel pump was going out.

 

Well round one failed.
Now the car starts but instead of the usual idle jump to ~1,800 rpm and then decline as it heats it only jumped to 1,000 rpm and the idle was fluctuating up and down about 300 rpm for maybe 6 seconds and then it died.

I'm going to try again now and gonna jump the diagnostic port while it's drying to see what codes I get. I should report back in a couple hours. I'm also going to see if the local autozone has an MAF. Would be nice but I'm not exactly hopeful. I still have my employee discount from when I worked at the Lexus dealership but I'm expecting any MAF they have to still cost me way too much as that discount was p worthless.

 

did you reset the ecu, give it a couple or tries, or blow some more air into it and try it again.
have you done your cap and rotor before? may want to give it a quick visual at least the rotor if you have time.

 

No, I didn't reset the ECU before I started, should I do that?
And do you mean blow some air into the intake? How many tries should I give it before cleaning it again?
I replaced the cap and rotor at the top of this thread with a brand new bosch rotor and bosch cap. My old rotor was a mess and the (for lack of a better word) little things on the inside of my old cap were calcified and one of them was charred pretty bad. At the time I thought that was what was causing my problem but replacing them did nothing.

 

Have your fuel pump looked at...