Brainzz

scsexy

iTrader: (1)

Thats too much fuel. Could be computer or some problem with injectors i'm leaning ecu tho

Brainzz

KahnBB6

iTrader: (5)

Which of the two catalytic convertors did you replace? The front cat or the rear cat?

A while back I found that despite having a new rear cat fitted (a Catco CA legal unit) it was my front cat that ultimately made the difference after a lot of other parts replacement and troubleshooting to eliminate CELs I was having on my '93 OBD1 SC300 CA-Emission spec SC.

As scsexy said you should rule out any ECU capacitor issue in your ECU. Get a spare ECU if possible to test with over the long term. You can get your original ECU capacitor serviced either by Tanin Auto Electronix or if in a jam and need a very fast turnaround, get your ECU to Driftmotion in Montclair if you're in or near SoCal/L.A. They do the same service as well.

However I will note that after servicing a lot of components in my SC's entire original stock ignition, fuel, ECU control and emission systems back in 2016 leading up to my smog test due date I finally discovered that even after replacing my #2 cat with the new CA legal Catco unit I still had high HC's and finally had to get a new OEM #1 cat which apparently had gone bad. Then my HC's, NOx and CO numbers were all in line again.

So with the other work you have already done I would check/verify good function of:

--Main ECU with no capacitor issues
--Good #1 and #2 cats. Both of them. Catco will make to order a direct fit of either with the correct sensor bung in the right location but it helps VERY much to contact them at Caatco/Airtek directly and send in an old OEM example as a template. A pain, I know as most of us do not have spare OEM cat assemblies taking up space in our homes. The #1 cat is made so specifically that's the one I'd do it for more than the #2 which almost any exhaust shop can take care of for you so long as you have their OBD2 CA legal universal equivalent cat. The shapes of all the SC300 cats from 92-97 don't change btw despite some being legal for certain model years and not others.

If you had any EGR CEL I would have suggestions for that but you don't so I assume you're good there.

For the ECU, to really get a good test result you'd need to plug in another known or confirmed good identical part number ECU. Assuming you know the basics for pulling back your passenger side floor carpet and removing the thick plastic ECU cover underneath it, take note of the Toyota factory part number on the face of your ECU (and just FYI it doesn't hurt to carefully stabilize the thermal paper that ECU label is printed on with some clear packing tape since those old labels tend to scratch away over time).

Now take that part number and either find another one in a Marketplace WTB section or try looking on ebay. It is very important that you use the same part number ECU to match the emission spec and transmission type.

We have a partially compiled list of ECU part numbers here but I am afraid that for 1997 SC300 Automatics (I assume you have an original auto car) we don't yet have the differing part numbers for the Federal and California emissions versions.

https://www.clublexus.com/forums/per...s-by-year.html

Wishing you luck. I know it can be a pain to diagnose this stuff in time for testing deadlines.

Brainzz

KahnBB6

iTrader: (5)

Aaron will take care of you with the ECU. He's very thorough and the procedure is pretty much the same for most of the 1985-1997 Toyota/Lexus ECUs that can develop the capacitor issue. The only thing he cannot do is test it in a vehicle-- that's a service that Tanin Auto Electronix does offer with their ECU repair services.

Aside, the only thing I recommend if you decided to send to Tanin is to avoid using any overnight mailing service to or from them and especially avoid Fedex Overnight (once, Fedex Overnight just lost a rare CA Emission 5-speed manual ECU that was coming back to me from Tanin. NOT Tanin's fault-- Fedex Overnight's fault. Regular Fedex service is fine).

Let Driftmotion inspect your ECU first and give you their recommendation. Also, when I had Tanin Auto work on a couple of my ECUs they said they tend to work on the "injector driver" part of the two logic boards. I am not sure what that specifically involves in terms of repairs but I brought it up to Aaron and Odom @ Driftmotion when I sent in another ECU to them and it seemed not to be something they felt was needed unless a problem were identified by them. Not to confuse you with this information, just something to bring up to them if you wish. Both Driftmotion and Tanin know their stuff with these ECU repairs and stand by their work.

Also, for catalytic convertor #2 if you are ever replacing it with an aftermarket unit I highly recommend, if you have a CA-Emission or OBD2 SC300, that you have the exhaust shop cut out your stock #2 cat's O2 sensor mounting bung (the third O2 sensor on CA Emission SC300's) and transplant it onto your new aftermarket cat pipe assembly as close to the cat as is possible without actually compromising the new weld-in cat. Even Catco's direct fit #2 cat doesn't have the correct mounting flange for the correct OEM-spec Denso O2 sensor that is supposed to go onto it under the car with a wire connecting just on the inside of the trans tunnel in the stock setup.

It's not much extra work and you can basically keep reusing the pipe and keep having new #2 cats replaced every so often as needed without affecting the transplanted OEM third O2 mounting flange. But this is a good reason to hang onto or substantially reuse your old OEM catalytic converter assembly in CA. Or to at least hang onto old intact full cat assemblies with the pipes still on them in order to ever have a correct "direct fit" aftermarket replacement made by Catco/Airtek, Magnaflow, Walker, etc. using them as templates.

Sony1492

Make sure the car is fully warmed up when you arrive for the smog test, the catalytic converters only work when they're hot. (In excess of 600°F)

I would look at the ect sensor to make sure it's still working properly. Engine coolant temp has a large effect on fuel, and testing it just requires a multimeter.