ray2828

I’ve been doing a ton more research and didn’t know if this could be an issue but when I let the car sit overnight my brake pedal is super stiff the next morning as if I was pumping the brakes with the car off, no problems braking at all but I sometimes do hear a humming noise when braking at high speeds like 70-80mph, and I have tried listening closely to the engine bay and I hear a slight hissing or high pitched noise somewhere in there, also I noticed when I did stall that one time since I replaced the sensor it was when I came to a relatively quick stop and it stalled immediately, the other time it almost stalled I was just sitting at a light but it corrected itself, could it be possible there is a vacuum leak or a brake booster issue? Just trying to rule stuff out before I go digging around for the ecm

isfvss

Do a smoke test to check for air leaks. You could change the brake booster pressure valve, just some ideas good luck.

ray2828

Dont have a smoke machine but im going to try and figure something out, thanks

lobuxracer

iTrader: (2)

Aw man. That's a bad brake booster for sure. I replaced mine not terribly long ago because it was bleeding down quickly (it should hold vacuum for a few days, not a few minutes), and you could see fuel trim going bad when you pressed on the brake pedal. That could easily be the root cause of all the problems you are having. Replacing the booster isn't simple, but it's not horrible. The down side is, the booster is ~$500 from Internet sources. Also, I'm pretty sure the reason they fail is because the seal around the two internal rods wears and starts to leak. It sounds like yours isn't just leaking a little, but it's leaking a LOT.

isfvss

Do the brake booster valve first cheap and easy. how many miles on it the booster should last for a bloody long time eg 200000miles it is a LEXUS after all cheers.

lobuxracer

iTrader: (2)

I wish mine had. My Supra only has 160k miles and the booster is toast. Toyota uses Bosch boosters.

ray2828

Did another test today and hard braked, stalled at the light, started right back up just fine and drove away without issue, tried doing it again a few times driving back home and nothing happened, but then a after I came down from at 65mph and came to a relatively hard brake it started to almost stall and then I rev'd it to keep it from stalling and then it just hovered around 1000rpm (very high idle) for about 5 -10 seconds then it settled back down, so it doesn't happen every time, I even tried flooring the brake pedal in park in a parking spot and nothing happened, not sure if all these things are connected, I am going to call a shop tomorrow to see how much they will charge for this, thankyou lobux for your input it has helped a ton, please let me know if this still sounds like the brake booster

lobuxracer

iTrader: (2)

It still does smell like that right now. Better to datalog and see what happens when the brake is used. That's easy enough to check.

ray2828

Alright I went on a drive today to do some more testing and yet again the crankshaft sensor seems to have only worked for about less than 100 miles, as soon as I reached operating temps the car would stall out at lights over and over again, even when I wasn't pressing the brakes hardly at all, and it was the worst it ever was today it was even almost bogging and stalling out at like 10-15mph coming to a stop jerking all over the place at low speeds (it was also the hottest day of the year so far about 85 degrees Fahrenheit)so the hotter it is outside the worse this gets by far! At this point im now leaning towards the ecm again, also tried testing the brake booster and i took the vacuum line off and felt a vacuum with the car on so it passed that test, also turned the car on put my brake to the floor, turned the car off and waited 30 seconds with the same amount of preasure and my pedal did not want to raise up so it passed that test as well, did not have time to test the check valve screwed into the booster tho. Im not sure why the sensor only worked for like 100 or so miles, it is a DENSO part so I feel like its not the part failing, where else should I go from here. (Also called a specialty shop waiting to hear back from them for a quote for the brake booster and the dealership quoted me $2200, definitely not going with the dealership but was just calling around for prices) I am not sure if changing the sensor did like a temporary reset for something with the ecm or what, im honestly so lost at this point.

lobuxracer

iTrader: (2)

Everything is pointing to the ECM or battery/alternator at this point.

USB813

this whole thread hurts my head.

ray2828

Hey Ive found another issue with my car, everytime I hit the rear defroster the car just completely shorts our and dies everything turns off but I can feel my hvac system still blowing air and when i try to restart the car i hear the key chime but nothing happens when i press the start button, the steering wheel will just move up and down, only after around 30-40min i can restart the card and it cranks for about 5-7 seconds before it wants to start. I took it to a shop to finally have them look at it and they checked every single wire leading to the rear defroster circuit and they boiled it down to a potential bad head unit, so they told me to buy one and then retest to see if it solved the issue. I bought a new head unit and same thing happened, but i noticed this time that my tpms light went away (i dont have tpms sensors in my aftermarket wheels, so the light will stay on), ive tried starting and stopping my car multiple times but the light still wont come back on. I called the shop back told them everything that had happened the other day and they said at this point with the stalling and weird electrical issues its probably a body control module and to start with buying and replacing the ECM. Im open to doing the lpfp only because I have no idea where to buy and ECM, ive heard really bad stuff about flagship1 "refurbished" ecm's and lexus no longer makes these so im kinda of stuck on what to do now. if the lpfp can somehow lead to the rear defroster issue (which i know it probably wont) im open to hear any ideas. Just to note i have only pressed the rear defroster when the car has been at an idle, never while driving. and who knows, my ecm and lpfp might both be bad but if everything is pointing to the ecm id rather do that first because of all the other strange electrical issues i have.

USB813

I think a Hyundai Elantra under warranty is in your future bud. fr fr no cap.

ray2828

Just wanted to give an update, was able to find a blank OEM ECM, so I went a head and ordered it, going on vacation around the time it is supossed to come but once i come back I will make an appointment with the lexus dealership to write my vin and reprogram my key to the new ECM, should have an update my middle of July hopefully, really hoping that this is the issue to all of my problems and that I can get back to driving this thing soon.

ray2828

Coming back to this thread, while i was on vacation the order for my ECU got cancelled because the part was out of stock, tried looking everywhere online, cant find a used or new ecu anywhere, I started the car up and let it sit in my driveway for about 2-3min and as soon as the rpms dropped it started to stall out. it seems that the stalling happens quicker and quicker the hotter it is outside, it was around 100 degrees fahrenheit. Since i cant find any ecu i guess my next best option right now is to send it to get tested/repaired, does anyone know of any reputable shops or websites I can send my unit too, also should I flash the car back to its stock tune, it has an rr racing tune at the moment.