charger980

My 1992 SC400 has been acting up. It will start and run fine until it warms up. Once it's warm it will start to sputter and shake at all revs. Giving it gas barely does anything. Exhaust smells rich and it will eventually get to a point where it will die. All attempts to start it while it's still hot result in about a second of running before it sputters out. MAF Seems ok, IACV is clean and working, a visual check on the ECU shows no signs of blown capacitors. Any suggestions? Sometimes it does it in all gears: Park, Drive, etc. other times it only dies in drive or reverse, and is fine in park or neutral. Help!!

SC400slide

iTrader: (11)

Somebody just had this problem yesterday, literally. It actually ended up being the spark plugs. Pull out some and see what they look like. Remove one coil on each side at a time, and try and start the SC. If it wont start without that coil, that coil is good. You get the idea.

Ali SC3

iTrader: (10)

yeah all the simple stuff and the ignition and def check the coils.
https://www.clublexus.com/forums/per...on-issues.html

Bankswood

It seems this is all I ever post but I would do the 12v mod. My 93 had many of the same issues, especially starting cold but refusing to start hot.

charger980

Replaced all the spark plugs before it started serious problems, just looked tan and dull to me. Unplugging the coils make it run even worse, so I don't believe it's ignition. MAF isn't throwing a code, and I cleaned it just to make sure. I think it's fuel and I will try the 12v mod. Anything I should know about the 12v mod? Will it wear out the fuel pump, or is there any rush to start the car since the pump is already building pressure? I'm also replacing my fuel filter (stripped fittings are a pain, if anyone can lend advice on that please do) just to make sure.

xxtoobsxx

iTrader: (4)

I tell everyone to check the timing. sometimes it skips a tooth or 2 or when someone installs a water pump they dont do the timing correctly. Set it to TDC and check the timing ...remember you have 4 cams in that beast!! chances are that it is probably set 180 degrees out!

Ali SC3

iTrader: (10)

How did you clean it, cleaning the maf can cause those symptoms shortly after spraying mostly anything into them because the little mirror inside gets dirty and you cannot really even reach it but the fluid will get up in that black plastic housing and then you will have to hope it eventually dries out or its time to find a new maf sensor. same reason I do not use K&N filters on cars with karman vortex maf's (so all odb1 sc300, sc400, and 7mgte).

xxtoobsxx

iTrader: (4)

^^^^ I didnt even see the part where he cleaned it. That could do it too

charger980

Problems did not worsen after cleaning it, and the toyota tech himself said it wasn't that type of MAF; ugh. Anyway how exactly do I check the timing on this engine?

Ali SC3

iTrader: (10)

well not every toyota tech knows what they are talking about, I on the other hand, try to only tell others what I actually know and your 1992 sc400 has a karman vortex maf and if you look on the back of the maf cleaner it will actually say do not use on cars with karman vortex air meters. It specifically says to only use on hotwire maf's where the residue is burnt off by the resistor. there is no heat in a karman maf, the electric sensor detects the rate of disturbances in the chamber and outputs a frequency type signal (steady 5V) as opposed to a regular 0-5v hotwire maf.
If you still are not convinced, take a look at the maf. If it is in a rectangular metal housing, its a karman maf. If it is a round black plastic housing then its a hotwire, and these only came in the later years.

just cause nothing got worse after cleaning the maf, does not mean that the maf was not already bad. Just something to think about. the last time I sprayed the cleaner into one of those mafs the car did not run right for several days until I kept cleaning and drying it and eventually it sort of worked.

you don't need to check the timing on a 1uz, its pretty much fixed. what you can do is remove the cam covers and set it to TDC and verify that the notches line up and are in the right position indicating the belt has not moved since the belt was set. if they are no where near the right spot, turn the crank around one more time and check then they should be close or dead on.

charger980

How did you clean and dry the MAF sensor? I might have to do so. As for timing I don't believe it's the issue; I'm trying the 12v mod tomorrow and see if that's my problem.

RWDorGTFO

From the information provided, it definitely sounds like a fuel issue.

xxtoobsxx

iTrader: (4)

It needs to be dead on...these motors are finiky to this. But have no fear you wont cause any valve damage if its super miss timed!

Ali SC3

iTrader: (10)

there is no good way to clean it I used to just spray some cleaner while holding it upside down so everyting runs out, then I would put some compressed air through it with a can, not the big compressor kind. it only worked like 1 out of 5 times so yeah I don;t really recommend that to anyone. oh and also use a hairdryer, and it may need to dry for a day or 2. really a last resort if your maf if good you will most likely end up hurting it this way, but if you have already sprayed cleaner over the black plastic housing and inside it then the compressed air wont hurt, just dont do enough to break things.