Sfmitchell3

Hi everybody
I just purchased a near mint 1996 LS 400 with 135k . The car runs and drives perfectly when cold but when it gets up to temp starts misfiring on cyl 1, 2, and 8. Codes PO300, P0301,PO302,PO308. Check engine light blinking and Tracs light blinking.
I'm going to start tearing into it in the next couple of day but have no experience with this engine and looking for advice on where to start.
Because the misfires occur on both banks I'm thinking it's not related to plugs,wires, cap and rotor but will probably just replace them as maintenance items anyways.
Could this be an ECU issue?
Any help would be appreciated.
Thanks

paulo57509

This is something that shouldn't be ignored. IIRC, the ECU sticky mentions that it's a not if, but when issue. You can "look" at other possible causes for the ignition issues but I wouldn't throw money and parts at it without solid confirmation that something other than the ECU is at fault.

Sfmitchell3

Thanks for the reply. I have read through that sticky and I'm leaning towards the ECU. Any recommendations on a good place to buy a rebuilt ECU or where to have mine rebuilt?

as99east

Jim Walker aka the Lexpert does quick turnaround in my experience and will rebuild for $295 plus shipping. When I got my 1995 it was the first thing I did. He said one of the capacitors had just barely started to leak but otherwise we caught it in time which makes the job much easier. Generally I think better to go the rebuild route vs a new one unless you depend on the car and can’t have it out of service or your current one is beyond repair. It may be a good idea to pop yours open and have a look you just want to be cautious and careful.

Sfmitchell3

Pulled my ECU and opened it up. I only found one capacitor that has leaked. Could this cause the misfire problems? Or is it a seperate issue?

as99east

I have definitely heard of ECU issues causing misfires. One guy on here I remember chased a misfire for a while and replaced a ton of parts before figuring out it was the ECU. Regardless, you definitely need to get the ECU fixed before there is any more damage (as it is, I would send comprehensive pictures to any repair shop before mailing to make sure they don’t think it’s a write off). You have at least one actively leaking capacitor so time to address that ECU ASAP. The longer it leaks the harder it is to fix until it gets to a point where it possibly can’t be fixed

paulo57509

Please read through this link before sending off your ECU for repairs or replacements. Quality components are as important as the work.

https://www.clublexus.com/forums/ls-...capacitor.html

Yamae

It is one of typical failing capacitor problems to have "The Misfiring multiple cylinders when warm". You definitely need to refurbish the ECU. I worry that traces are already damaged and those also should be fixed. Hope the damage is only the surface.

Sfmitchell3

What is the best place to have the ECU refurbished that uses that has experience and uses the proper parts?
Lexpert was mentioned. How do I contact Lexpert?

as99east

thelexpert@gmail.com