tylergrins

95 ls400 ob2 Car running rich. Codes thrown are maf egr and ecu/battery ..originally started from my 02 sensor furthest back on driver side. All but one wires got cut and sensor its self was almost out could loosen and tighten with fingers. Re wired it wires were color coded so that was easy. 02 sensor is really banged up and end is pretty bent. Didn't make a difference fixing it. Bought maf cleaner cleaned egr and maf..still running rich when I unplugged maf it runs exact same as it would be plugged in. Car idols at 1500 step on it nothing but super black smoke. No 02 sensor code though which is weird. Went to autozone few hours ago they had a maf for a 96 which is ob2 and mine is a 95 also ob2 only thing they were different part number but clips match up plugged it in nothing changed. Yes I reset the ecu. I took off cable from battery while I switched them out turned it on still black smokes. Every time I start the car I have to wait for the car to start. Meaning if I don't let car prime for a few seconds and imidietly turn car on when I put key in the car I'll die. But if a wait a few seconds it starts right up. Looked through a lot of forums no one seems to have this problem. Thanks in advance.

RA40

iTrader: (6)

Welcome to Club Lexus.

Two possibilities and both would be areas to fix if they have not been done. At least you are getting some codes.

For supplemental reading. The ECT sensor tends to allow the car to run rich. The other is this thread that is a common but not necessarily so with the conditions you mention. It does help knowing that the ECU is communicating properly for basic operations:

The ripple test:
https://www.clublexus.com/forums/ls4...-by-yamae.html

ECU discussion:
https://www.clublexus.com/forums/ls4...capacitor.html

Rich fuel mixtures tend to clog the EGR . That rich mixture does have consequences with the O2 sensors and cats at the later stages.

tylergrins

if I take out ecu is there a visible of bad caps? What should i look for? At the moment my multimeter won't read that.

Yamae

You even didn't read the first explanation. It says,

IMPORTANT: The capacitors may look perfectly fine and yet be bad, they look great at first, then deteriorate and cause damage to the ECU very quickly

The ripple test is an easy way to check.

RA40

iTrader: (6)

Taking the ECU isn't hard but testing it first using the ripple test will save you time. That is almost a 99% given you'll be in there to replace the caps so removing it and replacing at the same time is easier. At the mention you have to "prime" the car, does that mean it is turned to <on> before you engage the starter? That to me signifies that the caps are discharged in which case, the ECU is a high fault possibility. Yamae can verify further.

dicer

Some thing else that could cause an incurable rich condition, could be a leaking cold start valve, or its associated circuitry. I had that once on a FI 75 VW. I know they use them on 90 to 92 don't know about the rest of the years.

tylergrins

Found problem I hope. Seems to be a transistor in my ecu found one that is horrible and one not so great. Any one know where to pick up transistors for these ecus? Won't slow me to upload pics.

tylergrins

Went to radio shack no help and same with a big name electronic place here called Eliot electric. Any ways they told me there is nothing the can do for me capacitors yes because of having I'd numbers on them but transistor or transformer what ever it may be is in findable. Apparently Lexus doesn't provide a schematic for helping with that. I ended up purchasing a refurbished ecu and that still didn't fix my problem of running rich.actually my car wouldnt even start. It would turn over but no start.For some stupid reason I never thought to check fuses under hood. I found dome light fuse and efi fuse was out new about dome but not efi. Anyways replaced it car still wouldn't start.decided to call it a night get car drivable again and put old ecu with burnt parts and caps that look to be going bad. But it ran great from then on. I have no idea what those two burnt pieces do but every things works perfect again. Weird ****. Thanks for help though guys!

Banshee365

Been there. I found the reference voltage on my ECT circuit was wayyyy off. This was causing the car to always think it was cold. It ran great when it actually was cold but when it warmed up to operating temp it was still throwing lot's of fuel at it. It smelled like sulfur when following the car, idled very low, was hard to keep running, and wouldn't restart when hot.