Hello and thanks in advance for any input at all.
So I bought my 1997 Lexus LS400 just about three months ago. When I got the car the check engine light was not on and it ran like a top. The only thing it needed was the front two catalytic converters. It had the one further down the exhaust pipe. I replaced it as it was hard to start one day well didn't start so I drilled holes in the converter and managed to get it started. Then I had the one replaced and the sections where the front 2 would be are just exhaust pipes. The code that popped up at that time was the P0420 bank 1 & P0430 bank 2.
A few weeks later the check engine light came on and the car wouldn't start. Code P1600 ( Batt malfunction) Came on. It would eventually start but it took a lot of cranking. I might add the days that it did not start, There was spark, Fuel, and the fuses and relays were visibly ok.

I went through the starting and not starting certain days week after week. So I just replaced the computer and got rid of the P1600 code. I got the ecu from a wrecked ls400 off Ebay. The car runs alot better and idles a heck of alot better too.
I found this strange. I replaced the ecu and didn't have to program the immobilizer??. I bought the car with the pink slip stating that it is a 1997 but starting to believe its a 1996. When I put the new (used) ecu in it started up first try??

So I thought it was the ecu making it not start certain days but was not the case. Thats where I'm at. What could be making it not start certain days?? Would like to mention that 2 days that it rained the car wouldn't start but other days it was freezing cold...bellow freezing actually.
ANY thoughts would be appreciated.


Maxamus

 

Have the ECU rebuilt, I have the same issue with my car. turns out depending on the temperature it would not start. Once the temps get up over 50 degrees it started up like nothing happened. I would let it sit overnight and try to start it the next morning, nothing. About noon and temps are higher than 50 degrees would start right up.
Opened the ECU to find leaking caps. Had the ECU rebuilt and that fixed my problem.

 

Hi and thanks for the response.
I did open the original ecu and the capacitors were fine. I was al ready to replace them. I called the guy that I bought the car from because it looked great in the inside and he stated that in 2014 he had the ecu replaced. I was hoping that that would have been the end of it to replace the capacitors but not the case.I did also keep the old ecu. The day I replaced it, it was working. So I reinstalled the ecu (original one) and the car didn't start with neither. So leads me to think that there is something else related as I had that ecu in the house where it was nice and toasty. So today it is running perfectly and the temp is 34 degres


Thanks again

 

ECU is very common in older models, and it sounds like the case here. they aren't a DIY project, which needs a proper steady hand and right value capacitors to do.
link to main thread:
https://www.clublexus.com/forums/ls-...capacitor.html

the replacement ECU could still be bad, and I don't understand drilling holes in the cat...

 

Thanks a lot for the input. I will take the ecu out and have a look at it. I will take your advice and have it rebuilt.

Thanks again

 

Maxamus- You won't be able to tell if these electrolytic caps are still good or not by visual inspection so make sure to replace them all w/ equal or better parts. There are many posts on this forum that will point you to a list of quality caps (manufacturer, p/n, value & qty) so do a quick search & you'll find it. Good luck.

 

Im looking for a good place to have my ecu rebuilt. Can you send me the info of where you got yours done at??