LS400 question please help CAR WONT STAY ON

hi im new to this place but i would really love some input of what u think is wrong with my car ...
My car has been working fine till one day i went to the liquor store and  when i was pulling out of the drive way my car all of a sudden shut  down when i made the turn ..so i put it in neutral and started the car  up but when i pushed on the gas it was jerking.  CHECK ENGINE LIGHT  TURNED ON!! and everytime i hit the gas it would jerk so i drove  straight to the buddies house close by and he scanned my car and it gave  me a error code stating p0100..Mass or Volume air flow malfunction...
so i drove my car home and in the morning...when i hopped in my car and  cranked it on it would die right away.. i would have to keep my foot on  the gas to get it to stay on and then it would just idle really rough  and u can smell the gas really strong like its running super rich..Next  day i switched my MASS AIR FLOW SENSOR and it still wouldnt work..it  starts up but wont stay on please help me give me any ideas what u guys  might think it is..

battery, alternator, fuel pump?

Make sure everything is tight from filter to intake manifold (to include connections). Also, make sure there are no obstructions in the path.

Ok, we ran into this issue with the positive battery terminal. First start the car in neutral, see if it stays running. The neutral safety switch could be going bad. If that does not fix it, check your positive battery terminal. They are known for becoming corroded and causing running issues. The best way to check is unbolt both wires on terminal, clean them thoroughly, then reattach separately to terminal, not one on top of eachother. 
 
If that does not work, unplug MAF. If it is a bad MAF, unplugging can let the car run, it will run rich since it is not getting an air reading for the a/f ratio. 
 
Start there, then we can go farther. Rule out the basics. :biggthumpup:

[QUOTE=Mr.Doback;423842]Ok, we ran into this issue with the positive battery terminal. First start the car in neutral, see if it stays running. The neutral safety switch could be going bad. If that does not fix it, check your positive battery terminal. They are known for becoming corroded and causing running issues. The best way to check is unbolt both wires on terminal, clean them thoroughly, then reattach separately to terminal, not one on top of eachother. 
 
If that does not work, unplug MAF. If it is a bad MAF, unplugging can let the car run, it will run rich since it is not getting an air reading for the a/f ratio. 
 
Start there, then we can go farther. Rule out the basics. :biggthumpup:[/QUOTE]

i know its not the battery terminals cause they are super clean!!!...and i know its not the MAF sensor cause i just bought it today its brand new!..

Check neutral safety switch still

[QUOTE=Mr.Doback;423847]Check neutral safety switch still[/QUOTE]
where is that located

If you read in my post, the way to check is starting the car in neutral. If it allows the car to run, its the neutral safety switch.

I'll try that neutral switch

go buy some carb cleaner and clean out your throttle body...

[QUOTE=flexinsteelz;423911]go buy some carb cleaner and clean out your throttle body...[/QUOTE]

That might help, but unless he was having major idle issues prior, it would not keep the car from running. If higher mileage, still a good housekeeping procedure.

Did you try unplugging the battery and plugging it back on to see if the ecu will reset?

[QUOTE=MrExecutiv;423937]Did you try unplugging the battery and plugging it back on to see if the ecu will reset?[/QUOTE]
yea i tried that i unplugged it for 5 mins then put it back on still the same.. its cranking up just wont stay on ..if i keep my foot on the gas and let it heat up it will stay on but it idles really now and when i just rev the gas it will die once the rpm goes down.... please hELP!!!

Maybe your idle control valve is clogged...?

[QUOTE=flexinsteelz;423911]go buy some carb cleaner and clean out your throttle body...[/QUOTE]


free diagnosis right here.. unless u wanna keep replacing unnecessary parts.. but im only a lube tech, i dont know much..:biggthumpup:

[QUOTE=flexinsteelz;423952]free diagnosis right here.. unless u wanna keep replacing unnecessary parts.. but im only a lube tech, i dont know much..:biggthumpup:[/QUOTE]
yea bro but im in san diego california ur in sac town ...its not really gonna work for me ...

my buddy said it could be a vacum leak so imma check the hoses tomorrow and see if thats the case.

i dont even need to touch ur car or meet up.. im just giving u some free diagnosis right here... take off your intake hose and clean out the throttle body with carb cleaner.. i've only done this at least 50 times, cars including, tundra, sequioa, ls400, ls430, gs400, ect...

[QUOTE=flexinsteelz;423958]i dont even need to touch ur car or meet up.. im just giving u some free diagnosis right here... take off your intake hose and clean out the throttle body with carb cleaner.. i've only done this at least 50 times, cars including, tundra, sequioa, ls400, ls430, gs400, ect...[/QUOTE]
im gonna try that bro thanks for the input and not sounding like a dick :)

[QUOTE=flexinsteelz;423958]i dont even need to touch ur car or meet up.. im just giving u some free diagnosis right here... take off your intake hose and clean out the throttle body with carb cleaner.. i've only done this at least 50 times, cars including, tundra, sequioa, ls400, ls430, gs400, ect...[/QUOTE]
+1 on this dudes advice. Carb cleaner is cheap so why won't you(OP) at least give it a shot...

Sorry I didn't see that you got the battery tested. Did you try that? Sounds like a power problem not an air/fuel one. No battery charge and running directly off the alternator can cause these symptoms also.

[QUOTE=augdogg;424026]Sorry I didn't see that you got the battery tested. Did you try that? Sounds like a power problem not an air/fuel one. No battery charge and running directly off the alternator can cause these symptoms also.[/QUOTE]
yea im pretty sure its not the battery cause everything turns on and it cranks up but dies right away so im sure its not that...

if that didnt work, id seriously get the fuel pump checked

If it was alternator related, the battery would be dead, here the car starts up immediately and runs, then dies, not holding idle. 
 
IAC is a possibility as well as someone said.
 
Have you tried starting the car in neutral yet?

Alt prob works but battery won't hold charge. How old battery?

[QUOTE=augdogg;424090]Alt prob works but battery won't hold charge. How old battery?[/QUOTE]

Battery is fairly new ..so I went and got my car towed to the my buddies shop and he checked it out and made some adjustments to my throttle body and he said that it could my throttle body and whatever is on the rightside of it is going bad and he said to try and go to the junk yard and get a oem maf sensor instead of the one I bought from autozone...but as for now the car is staying on and its running but its running very rich cause u can smell the gas and carbon ? U guys have any ideas

sounds like the throttle body service fixed the idle issue..

as far as running rich, it can be anything from the MAF, throttle body  out of spec, coolant temp sensor, o2 sensor, gound circuits, evap purge  valve stuck open, etc.. These are thing your mechanic should be able to  scan with a good tool and pin-point what area is bad... Instead of just  guessing and replacing all kinds of unnecessary, have a good mechanic  take a look at it.. Kinda hard to diagnosis over the internet since we  cant see live data with a scan tool..

Also check EFI, EFI2, EFI3 fuses.. 

or u can try borrowing a throttle body  from a gs400, ls400 etc.. but if it went bad, 99% of the time you wont be able to accelerate which u said u can.. 

[B]Find someone local that has a TECHSTREAM scan tool[/B].. they should know what to look for..

thats the best advise i can give you for now.. good luck..

[QUOTE=flexinsteelz;424178]sounds like the throttle body service fixed the idle issue..

as far as running rich, it can be anything from the MAF, throttle body  out of spec, coolant temp sensor, o2 sensor, gound circuits, evap purge  valve stuck open, etc.. These are thing your mechanic should be able to  scan with a good tool and pin-point what area is bad... Instead of just  guessing and replacing all kinds of unnecessary, have a good mechanic  take a look at it.. Kinda hard to diagnosis over the internet since we  cant see live data with a scan tool..

Also check EFI, EFI2, EFI3 fuses.. 

or u can try borrowing a throttle body  from a gs400, ls400 etc.. but if it went bad, 99% of the time you wont be able to accelerate which u said u can.. 

[B]Find someone local that has a TECHSTREAM scan tool[/B].. they should know what to look for..

thats the best advise i can give you for now.. good luck..[/QUOTE]

Hey thanks man I will check those fuses where r those located under the hood or near the gas pedal im hoping its prolly a fuse

[QUOTE=onlythruyoeyezz;424180]Hey thanks man I will check those fuses where r those located under the hood or near the gas pedal im hoping its prolly a fuse[/QUOTE]
Fuse box under the hood, there's a sketch inside the fb cover.

[QUOTE=Juzzo;424311]Fuse box under the hood, there's a sketch inside the fb cover.[/QUOTE]
thanks bro ..so heres the update i got another MAF sensor from the junk yard and tried it on ...and i put it in and its actually idiling really smooth and its not smokey anymore ..yesterday it was pretty smokey when i had the sensor i bought from autozone on...but no its not smokey and its running pretty okay..only concern is the CEL light is still on maybe i have to reset the ecu or something or erase the code...still a lil more work but thats the update for now...it doesnt smell as much gasoline anymore either...My mechanic said just let it run to get all those fumes and toxins out..

That's good to hear, now unconnect your battery for ~5mins so the ecu resets. Then hope the CEL stays off.

[QUOTE=Juzzo;424337]That's good to hear, now unconnect your battery for ~5mins so the ecu resets. Then hope the CEL stays off.[/QUOTE]

Yea I hope so to bro thank u guys for all ur help

[QUOTE=flexinsteelz;424178]sounds like the throttle body service fixed the idle issue..

as far as running rich, it can be anything from the MAF, throttle body  out of spec, coolant temp sensor, o2 sensor, gound circuits, evap purge  valve stuck open, etc.. These are thing your mechanic should be able to  scan with a good tool and pin-point what area is bad... Instead of just  guessing and replacing all kinds of unnecessary, have a good mechanic  take a look at it.. Kinda hard to diagnosis over the internet since we  cant see live data with a scan tool..

Also check EFI, EFI2, EFI3 fuses.. 

or u can try borrowing a throttle body  from a gs400, ls400 etc.. but if it went bad, 99% of the time you wont be able to accelerate which u said u can..

[B]Find someone local that has a TECHSTREAM scan tool[/B].. they should know what to look for..

thats the best advise i can give you for now.. good luck..[/QUOTE]
hey bro i wanna thank u again for all ur help ur the reason my car is fixed...my one of my efi fuses were blown and alsu my euc-b fuse and now that i've changed both the car runs back to normal again.. i just cleared the code with the scanner and drove it for about 45 mines and it still hasnt came on thanks for all the input u gave me man it helped a lot and thank u all to everyone that helped with the situation :)

[QUOTE=onlythruyoeyezz;425394]hey bro i wanna thank u again for all ur help ur the reason my car is fixed...my one of my efi fuses were blown and alsu my euc-b fuse and now that i've changed both the car runs back to normal again.. i just cleared the code with the scanner and drove it for about 45 mines and it still hasnt came on thanks for all the input u gave me man it helped a lot and thank u all to everyone that helped with the situation :)[/QUOTE]


no problem.. im glad u took my advise and saved yourself some money.. 

theres too many parts changer in this world... its all about logistics.. :biggthumpup: