cpofwacotx

I've got a 94 LS400 that is literally driving me crazy! I bought the car as a project and I have to say, it has been kicking my butt! The starter was out when I bought it, so that was my first task that I had to take on. Got it finally up and going, but it was running like crap. Figured out that the ignition coils were the problem now. Replaced both coils and it was the difference between night and day. Now it has power, but it idles at approximately 1200 RPMs and hesitates when driving it. I've tried adjusting the throttle position sensor, but no difference. It's running extremely rich and exhausting black smoke. The check engine light is on and the trac light comes on and stays on after about 30 seconds running. For some reason, I'm unable to pull any CEL codes using a jumper wire. The check engine light will never start flashing any codes, just stays lit up solid. Bad TPS? Bad O2 sensor? Is there a way to test either of these? Any suggestions would be greatly appreciated!

LScowboyLS

normally, when an LS400 will not communicate its OBD codes, and is not running right, it is nearly always a case of failing ECU capacitors

are you sure your jumper is in the correct location?

Twista4004

Was just about to say the same thing. I've got the number to a guy who rebuilds Lexus/Toyota ECUs specifically for $149. If you don't mind mailing it off, I can give you the number.

Crybicki

Sounds very similiar to issues I was recently having. I did coil packs, and hollowed out my catalytic converters because the honeycombs inside had broken up, and I also had to do both distributor caps and rotors inside them. When the distributor caps/rotors go bad, you get unburnt fuel in your plugs causing it to run rich and to have smoke and excess fuel etc. Check out my post that I did on the overview, if you scroll down youll seee where I did my dist caps and rotors.

https://www.clublexus.com/forums/ls4...-problems.html

reammarc

what does it mean when you have white smoke with all the same symptoms?
raw fuel coming out of tale pipe.

MRLexus90

I know it's been four months, but did you ever fix the high idle/loss of power/running rich issue? You mentioned you just put in a starter so I was wondering if you possibly misadjusted the throttle cable? That might be your issue; you might check that it has a bit of slack in it at the butterfly plate and adjust the cable nuts accordingly... Just a suggestion? Also, as members on other threads have oft-pointed out, the coolant temp sensor on the intake water pipe is usually the culprit for poor performance as heat and age cause it to fail. Other than my suggestions and those of others, especially cowboy's suggestion of checking out your ECU's capacitors ESR resistance/signs of leakage, i'm not sure what else to suggest until all those have been ruled out. I've had my 90 LS since '96 and have done many such repairs myself over the years. If you do not have access to a factory repair manual, let me know and I'll send you the pages you need to adjust the throttle cable and the transmission kick-down cable. The correct procedure to adjust the TPS to factory spec is available already at http://www.lexls.com/tutoriaLS/EFI/tps.html . Hope this helps you or others!! Good luck!

RA40

iTrader: (6)

OP hasn't been back since that post so we'll not learn of the outcome.