TRDwhtMK3

Hi Guys,

I believe this is my first post on this board but I've been "lurking" for a few months now...

Long story short, purchased a '96 LS400 (love it!) to pair nicely with my '91 Supra. The Lexus had 230,000 miles, when I got it, everything worked perfectly with the exception of throwing an o2 sensor code and surprisingly, the car drives like its brand new!

Well I ignored the o2 sensor code for quite awhile, had the codes cleared and everything seemed to be A-OK until the other evening...

Basically, when I start the car when its been sitting for awhile and its cold, it runs and drives perfectly fine, that is, until it warms up. Once the vehicle gets warm it immediately starts misfiring in cylinder #1 and after a few drives throws code P0301. Its obviously misfiring due to the car shaking, low idle and terrible sputtering when driving.

Now since I've started troubleshooting I've done tons of searching and can't figure it out... I've replaced the plugs, tested the wires and all are within 3-8 mili-ohms and the problem has only gotten worse!


I still have not yet tried swapping the coil packs to a different set of cylinders to see if the code follows but I was wondering if anyone knew the specs for the coils? Perhaps I can test it without having to move it around.

Any info would be greatly appreciated! I am pretty good with anything car-related (got my supra to over 500rwhp all by myself, no shops) so I am no newbie to mechanics or working on cars. I just purchased this car so I have absolutely no info on it other than what I've found searching.

I just find it very odd that the car runs perfect when cold, then misfires terribly once immediately warm...

Elaboration?


EDIT: Also, the Trac Off light flashes once every second or two, and if I continue to drive the car, The CEL also flashes.

UPDATE: Car now starts misfiring/sputtering within 30 seconds of idleing and is now throwing codes P0300, P0301, and P0302. The car also runs much worse now than it did last night. Also, I am not driving this car other than for diagnosing, it sits otherwise because of this issue.

PureDrifter

iTrader: (10)

did you check the distributor caps/rotors?

TRDwhtMK3

I have yet to do that seeing as how its snowing for the next couple days but that is my next step. Any good writeups on this or anything I may need to know before I go ahead and do it?

Thermactor

iTrader: (1)

The wire might test OK but have an intermittent disconnect on-vehicle. Are the wires original? Since they're so long on these cars, they need to be changed out along with spark plugs around 10 years or 100,000 miles.
And if that doesn't do it, you ought to check the impedance on the fuel injector. Had an Avalon to fix that had a dead injector and caused the same kind of misfire.

TRDwhtMK3

Thank you for the recommendation Thermactor, I use to see you on supraforums quite a lot, small world :P but would you happen to know the resistance I'd be checking for, this will be the next thing I do if you could shed some light.

UPDATE: Over the weekend I replaced both caps/rotors and both coils and to my dismay, car is still misfiring exactly the same way, the misfire doesn't even seem slightly better. Again, usually when the car is cold it runs just fine, drives fine but as soon as it starts to get warm it starts misfiring terribly, causing the car to shake quite obviously at idle and have trouble getting to speed.

Thermactor

iTrader: (1)

When its warm and misbehaving, try pulling wires one at a time to find which cylinder(s) are misbehaving. I do still think that it could be the wires. If you want to check the injectors, the easiest thing to look for is an open circuit (no continuity) between the two injector poles. That's what went wrong with the Avalon.

Yes, I remember you too from SF. I miss my '86.5 NA-T so so so much. What an awesome car.

vdubill

Did u ever get this fixed?

LScowboyLS

from his symptoms, and the model year, this is highly likely to be failing ECU capacitors