keyaedisa

As title states I'm new to this platform. Some background is I have an is300 that I've manual converted and done various things to for street and drift purposes. I recently purchased a 96 sc300 and it is a non vvti model. it misfires very bad. i suspect that that spark wires from the distributor are bad. they have white stuff on them and when i was messing with them the car improved in how it was running. i've not checked codes but if there are any other things this car has that causes misfires please let me know. im going to do a full maintenance routine on the car before it sees any modifications. i have a few questions in that regard. Note: I will be doing further research through these forums of my own on these issues independently but figured I'd give opening a new thread with all these problems together may be worth a shot.

can i use a water pump and timing belt kit from an is300 on this sc300?
as far as i can tell the gaskets are basically the same save for some cutouts in the is300 which im pretty sure all the times i replaced mine those dont go to nothing anyways. i havent been able to see if the housings are different but i imagine they are all the same.

why is my speedo way off and my rpms seemingly too?
very strange. as i understand it these cars (as well as ls400s apparently) have ecu problems due to age. is the speedo being off due to a bad ecu? cluster? speed sensor? also not positive the tach is off bc im pretty sure this cars a 4 spd auto (planning on manual swap) and so like the ls400 i assume its always low in rpms and boaty. but still suspicious. everything else works seemingly fine on the cluster.

why doesnt my cruise control work?
bad ecu? no idea where to start here other than tearing into oem wiring diagrams and trying to figure out what all its working with.

what things typically go bad on these cars (if they havent already and ive not yet noticed)?
id like to really jus do my best at bulletproofing this car the best i can so that it can be manual swapped and raged on.

thank you for your time and assistance.

TLHSE

My speedo is also off pretty bad, but since mine has been sitting in a garage for the past 14 years, I doubt we're having the same problem . I would look into the speed sensors first (there are two), then the needle motor for both the speedo and tach. I doubt the ECU would have anything to do with it.

If you find a fix, let me know too. Thanks.

KahnBB6

iTrader: (5)

Welcome and congratulations on the SC purchase! I like IS300/Altezzas also! Very fun cars!

There are a few things you should check with misfiring behavior and this is a big general list without any narrowing down:

--Distributors rarely go bad. Usually it's the cap and rotor and wires. For all three of those it is best to stick with OEM and/or Denso OEM parts. Denso makes the best cap and rotor and the best ignition wires for these cars. Then check your ignition coil module (not the "Igniter"... that is a different component).

--Usually with the OEM distributors it is the little O-ring seal that goes bad and which causes some leaking of oil (easy replacement). In very rare cases the distributor's revolution sensor (same principle as a camshaft sensor on distributor-less engines) can go bad or the main shaft of the distributor itself can leak oil. In that case you would need to get a replacement distributor. One from a 2JZ-GE or 1JZ-GE will work and you can get these much cheaper by ordering them from Amayama Japan. But replace the cap, rotor, plug wires and ignition coil first... and also check to see that the terminal repair wires on the distributor's electrical connector going into the engine harness are all intact and not frayed. If any of those are damaged you'll need to source new terminal repair wires from Toyota and do some splice, soldering and heat shrink tubing repair. The connector can also be replaced.

--Since your SC300 is a 1996 model you also have a crankshaft sensor (which is also very good if you ever plan to go NA-T since it is already installed). You can check that as well but if it were bad I think it would have thrown a CEL code.

--The main engine ECU, if never having been serviced with new capacitors, should have that service done anyway. It is a common issue with these ECUs that after this many decades there is the risk of worn, bulging or leaking capacitors getting electrolytic fluid onto the circuit boards. Usually there is just the capacitor replacement that is required. The caps must be the same brand and same spec that came from the ECU originally. These are sourced from Digi-Key and Mouser. Tanin Auto Electronix can do this as a mail-in and send back repair upon special request.


Very good plan! We're here to help as you go through each stage. You can make individual threads in the sub-sections that we have for each category and you can also make a build thread to cover your restoration and modification progress.

I should know this offhand but I don't have as much experience with the GE VVT-i engines.

I do know that the water pump for the 92-97 Non-VVT-i & 98-00 2JZ-GE VVT-i engines in the SC300 and GS300 are exactly the same. The timing belts are the same. However the pump *may*(?) have changed for the IS300 engines...? I'm not 100% sure on that. I would double-check all your little associated VVT-i timing belt parts anyway with the non-vvt-i GE engines just to be sure.

--This can be a malfunction in your instrument cluster's speedometer gauge motor. Usually bad capacitors and more rarely a motor failure. Repairs for that can be handled by Tanin Auto Electronix if that is the case.

--The VSS sensor on the transmission could be bad but then it would probably just stop sending a signal at all.

--Some previous owner could have installed a different rear differential with a ratio other than the stock 4.272:1 that all SC300 Automatics came with from the factory... but that's probably not it.

--The tachometer having an issue with rpms being off *might* have to do with the issues your ignition system is having at the moment. And then again it could also have to do with the the tachometer gauge motor having bad capacitors or more rarely its motor could be failing. Usually it is capacitors. This is again a job for Tanin Auto to repair for you as a cluster-out mail-in and mail-back service. IF that is the case....

This could be several things. Check under the brake pedal for one to see if the cruise cancel switch and little rubber stopped are intact. Those little things are easy to solve potential culprits. Next you'd need to check the condition and arrangement of the stock cruise control unit (located in the passenger side of the engine bay just behind the air filter box) and its cable which goes to the throttle body.

Even more rarely could be an issue with the cruise control mode stalk on the steering wheel but that would usually only be an issue if the previous owner had messed with it improperly.

The main engine ECU could be related I guess but it is more likely something more fundamental to the cruise control setup. It is a very simple style cruise system.

This is a bit more than I can fully give the full rundown for tonight but these cars are tanks and fairly bulletproof designs to begin with.

--Front lower control arms tend to wear out and require replacements with OEM/factory front LCAs from a 1993-1996 Supra MKIV.
--Steering rack bushings go out and need replacement with polyurethane units from Figs Engineering.
--Engine ECU's all eventually will need servicing for brand new OEM brand and spec capacitors to future-proof them
--Instrument clusters can have backlighting go out (easy to fix), needle lighting go out (call Tanin Auto), or gauge motor issues (call Tanin Auto)
--Center vents all tend to crack eventually (some reproductions exist on ebay)
--Door lock actuator rods have these little inexpensive factory plastic clips on them that tend to break down over decades and which can allow the rods to free float and get caught/bent/broken by the descending window glass. These are $2.00 each left and right as a DIY replacement for preventative care. Also a no-brainer cheap thing to replace if you ever have to replace your door lock actuators or window regulators.
--The climate control HVAC control screen LCD panels tend to go bad. Kits are sold for this repair and Tanin Auto and other companies offer a replacement service to restore these LCDs.


Additional non-standard things:

--The front brake calipers and rotors on 92-97 SC300's are very undersized from the factory. If a wheel change is in your car's future, consider upgrading to 95-00 LS400 front calipers and rotors (4-piston), MKIV TT front calipers and rotors (4-piston) or a range of other OEM multi-piston front calipers and bigger rotors.

--The front headlights are a good 1990's early projector design but they originally use 55W Halogen bulbs as standard. Even if you use a headlight restoration kit (which you should) to clear up cloudiness like new again the original lighting system isn't as good as today's modern cars have from the factory. Organized Garage Status does some amazing (though pricey) headlight restoration and upgrade work. A decent cheaper lighting upgrade is a XenonDepot 4200K Phillips single-beam kit for the front low beams only.

--Also choose some good grippy tires for your SC that have good dry and wet traction characteristics. Almost everyone goes to larger than stock diameter wheels with much more width allowing some wide tires in the rear which is good overall for these cars.

- V -

iTrader: (1)

Kahn covered pretty much everything but I want to add one note with regards to the cruise control. It's very common for people to swap in a 3 spoke steering wheel on these cars because it modernizes the interior (i did the same) but even thought the module that comes with the newer steering wheel will plug into the connect, it won't actually work. If your car has a 3 spoke steering wheel then it is possible the previous owner didn't swap his original module from the old steering wheel and just plugged in the new one. If that's the case, simply buying a unit on ebay for the correct year should solve the issue.

deuce33

I have a 1998 sc300 that came with a four spoke steering wheel. I like the three spoke that came on the '99 and 2000. The dealer lists the price at $2000. Yes that's the correct number of zeros. A person on craigslist listed one (with air bag) at $150. It arrived and I assume it is an Rx300, since the leather was not perforated. (I actually prefer non-perforated). The plug fits, but the wire positions are different. Pulling out the pins and rearranging makes it work OK.
The '98 pins are BGWRblankB. The '99 pins are BGblankWRB. Don't need to buy anything.