Guys this is like my third post on the same problem. Keeps getting worse and worse.

It all started when my car stalled out on me while driving.

Than it was giving me trouble starting sometimes but would still be able to drive. Only stalled on a few occasions and would start back up again.

The cpu was throwing a code 41 (tps)and days later it was throwing a code 12 so I went and replaced the tps.

The problem started the next day again. Double checked the tps and it was fine.

Ive cleared the codes and now the problem persists but no codes.

The check engine light is still on but no codes.(check engine light stays on while key in on position-turns off when u start car-same as before when I had code 41 and code 12) Lexus dealer argued with me that the engine light code is supposed to stay on while engine is on and while driving, hence he says the engine light is not on. When I had my computer throwing two codes 41 and 12 the engine light did not stay one while driving-turned off immediately after car was started..is this normal?

I broke down and brought my car to the lexus dealer and they spent two hours on it.--------NOTHING!!!!!!

They could not diagnose the problem and recommended me to change the coils and the wires on the spark plugs. Seems like nonsense to me. Fuel system seems good, air sensor, exhaust from the back seems to be blowing ok(no clogs i dont think)

My regular mechanic is also not sure what the problem is but he thinks it could be a problem with the computer.

The fuel system is good-when the car runs it runs perfect-the tps is fine-air control sensor seems fine,------what else could be the problem?

The problem is becoming more frequent and getting worse over time. More frequent bad starts.

Guys I need some real pro's to help me on this. Even the dealer was no help.

Thanks in advance guys please let me know what to do next, im already in the hole and at square one still.

Thanks!!!!!!!!!!!!!!!!!!!!!

 

best option just swap out the ecu they are cheap and that's what it probably is...

 

I had a problem like this once, I had the wrong battery in my car; maybe not the problem but just a thought.

 

Swap the maf out also to chk

 

Is your sc a 300 or 400

 

Im thinkin ecu. How old are your plugs coils and wires? Im a lexus tech, tell the dealer to do what they think it is but your not paying for it if it doesn't fix it cause that is considered a misdiagnosis. Don't be afraid to get a little heated with them. Are they saying they can't duplicate it? Please tell me you also didn't pay 2 hours labor and they still didn't find your problem. If so i would loose my mind. Let me know what happens man and PM me if you need some more help.

 

What has any of your mechanics done to resolve the Code 12 problem. The Code 12 is a sign for a missing RPM signal. This is usually caused by a failing distributor or igniter. The SC400 has 2 separate "RPM"codes for this, Code 12 and code 13 since the V8 has 2 distributors.

 

is this a stock motor causing all this trouble?

 

Yes guys this is a stock sc400 engine. 140 000km.

The lexus dealer said it would be wise to change my coils and wires on the plugs but they say that it might not fix the problem. Ive spoke to other mechanics and they agree with me that changing the coils and wires wont fix my problem.

I have cleared the codes since replacing the "tps" and since than no codes have been thrown, even though the car has been stalling and not starting quite frequently.

I have purhased a used "ecu" and am going to pick it up tomorow.

I really hope this fixes the problem, it is getting a bit scary now.

Especially since this is my daily driver.

And no I did not pay lexus for the 2 and a half hours of labour that didnt do me any good.

They told me to never come back there though.

Guys please tell me exactly what the "maf" is and how to check it"

I assume it is the air flow sensor?

I once or twice took the air flow sensor out and cleaned it and it seemed to do nothing, in fact my car was a bit more sluggish for a few minutes after doing so.

I will let you guys know what happens tomorrow.

Thanks alot for the input guys, it is greatly appreciated!!!!!!!!

 

First step would be to reset you ECU and see it that fixes the problem. Next I would try swapping out you MAF and see is that changes anything at all. Contact Aliga for a MAF and ECU. Also is your TPS in the proper position? Adjusting it in any direction throws off your timing. Have you had that checked out also?

 

Thanks guys!!!

But if it was a bad "maf" or a dirty "maf" does it make sense that it would throw codes 41 for a "tps" and an "rpm" signal code 12?

Is the "ecu" really that unreliable to throw wild codes out there?

And yes my "tps" has been double and triple checked by local mechanics and the dealer, it is fine.

And how exactly do I reset the "ecu"?

Do you mean clearing the codes?, if so i have done that already.

If there is another meaning to resetting the "ecu" please let me know.

 

Take the battery terminal off for a couple of mins this should reset it.

 

Wow, at Lexus techs not being able to figure out a problem with a Lexus, then telling you not to come back.

Yeah to reset the ECU unhook the negative terminal for around 20 minutes.
How are the battery terminals anyways, clean with no corrosion..cables on good and tight?

 

try the ecu they do crap like that sometimes.