Hey everyone, I have a 1993 sc400. And Ive had this car for a few years. but I had this problem with the car for a while. It runs very rich. Like it smells like raw unburnt fuel. Making it stink whenever I drive the car. It also has no power, and I have to sort of "stomp" on the gas pedal just to make it go up to speed. Eg: 35mph. It eats 50 bucks worth of gas in a week. If anyone has any suggestions, please feel free to let me know. Thanks

Here is what has been done so far...

• bought new spark plugs
• bought new spark plug wires
• changed MAF sensor
• changed O2 sensors (4 total)
• changed ignition coils (2)
• gutted out the CAT converters
• bought second hand ECU
• tried the "unplugging" MAF sensor method. Kinda helped, car sounded a little better. But nothing extremely great.
• CATs are now being removed, and are being swapped with a different set.

 

You have thrown enough parts at it...take it to an experienced tech. It will be cheaper in the long run.

I wanted to add this so you don't think that I am just being rude. You are probably running way rich (look at a plug and it will be black) so you have to find out why the computer is telling it to do so. I have wasted lots o' money in the past throwing parts at EFI vehicles thinking I could diagnose it when the only way to do it right is to have the right equipment. A tech will be cheaper in the long run

 

Sounds like a knock sensor thing.

You never mentioned it, but you're gas mileage its being whipped from a lame ignition advance.

That's what it sounds like to me.

Oh and put the parts gun down!

 

cats won't cause a car to run rich. you are either getting too much fuel in (stuck open injector(s) or clogged return line, clogged air filter or other air restriction, or you aren't getting spark).
you did not mention the caps/rotors in the list. how are they?

 

Hm.. I'll try look at the injectors today, and I will post back asap. Thanks everyone for your suggestions. Oh, and I did take it to a shop(s) and even a so called certified Lexus mechanic. They all tried pulling codes from the ecu and couldn't get any. They forced some codes, so they could try and pull any, still, no codes. Hmm. Still puzzling.

 

I remember my mine was like that at first. My brother said that the throttle wire had some play on it (some slack). So he tightened it and it's been pretty good ever since.

 

I would say it is your Ignition Coils, did you replace the coils with a new or used set? Recheck the wiring/cords/connectors thats associated with the coils.

 

I've replaced the coils with new sets. Didn't do much tho. Any other suggestions?

 

I'm suprised no one said it but also have your coolant temp sensor checked. if it's not reading correctly ie:-40f, the ecm will DUMP fuel thinking it's that cold. IDK about the 400 but It's a very common problem for many many different cars. I live in NY which has a really cold winter and you should see what it does to gas mileage lol

 

Hmm. Idk. I'll give it a check. Anyone know an easy way to get out the front 2 cats?? I was getting frustrated trying to get to it hahah. Lmk

 

Did you find a solution to your problem? I've had this issue for a while now too.

 

i have this exact problem, like i have to start in low in order to get going anywhere. i heard it could be shift solenoids?

 

change out both your dizzy's

 

I was thinking it was the cats or ignition coils, but if you have already replaced them, maybe the TPS or fuel filter? Did this all of a sudden start doing this, or gradually over time?

 

mine was like it when i bought the car, so who knows