code 31 and 51

[87supraturbo19]

okay my car is hard to start when the motors cold. It will hit and run for a second for the first couple tries. then it will start and rev to about 2500 then die. once its warmed up it runs great except it idles at about 1200 to 1300. can i also by-pass my fuel pressure vsv? i read that somebody had done this with no problems. so heres my question. where do i start from your guys experience? my codes:
51Switch Signal
Diagnosis
No "IDL" signal, "NSW" signal or "A/C" signal to ECU, during diagnosis check.
Trouble Area
A/C switch circuit
A/C switch
A/C amplifier
Throttle position sensor circuit
Throttle position sensor
ECU


31
Air Flow Meter Signal

Diagnosis
(7M-GE) Open circuit in VC signal or short circuit between VS and E2 when idle contacts are closed.
(7M-GTE) Open or short circuit in air flow meter signal.
Trouble Area
Air flow meter circuit
Air flow meter
ECU

 

[87supraturbo19]

So i unplugged the afm and started it. it idled high but didnt stumble or die. if i remember correctly thats a give away that its bad right?


I also noticed maybe some ps fluid in the connector. contacts are corrosion free. ill see if that helps. still havent looked into the code 51. i found jetjocks write up on code 51. ill if that leads me anywhere.

any back up with the statement above would appreicated.

 

[2543arvin]

Okay first of all, if it runs with the AFM unplugged, it doesnt mean that the AFM is bad. You can check the AFM using the TSRM, and if you search the code 31 on this site you will find other threads that will help you check it further. When I had a code 31, it ended up being the AFM and not the wiring so I bought the LEX AFM with new electronics and it made the code disappear.

But search around because this has been covered many times.

 

[87supraturbo19]

i dont have a way to check frequency or have a scope. so i was looking for alittle reassurance for guess, although i want a lexus afm anyways. i just need a bullet proof reason to justify it. not for my wife or anything.:nono:

 

[2543arvin]

i dont have a way to check frequency or have a scope. so i was looking for alittle reassurance for guess, although i want a lexus afm anyways. i just need a bullet proof reason to justify it. not for my wife or anything.:nono:

Yeah, I needed proof that I needed the LEX AFM as well and the 550s. I just said my injectors broke along with my AFM. It worked.....

 

[87supraturbo19]

i am on my last leg with the supra i cant make any mistakes or she will cut the other one off. i will still have the supra but no legs to drive it.

 

[2543arvin]

i am on my last leg with the supra i cant make any mistakes or she will cut the other one off. i will still have the supra but no legs to drive it.

Ive been livin on my last leg.....trust me I hear ya bro!

 

[cuel]

You can do any of the electrical tests in the manual with a good multimeter. They can be used to test voltage, ohms, amps, etc. Most come with instructions. Go to Sears and get one. http://www.sears.com/shc/s/p_10153_12605_03481079000P?keyword=multimeter There's a decent one that has multiple functions, including an infrared thermometer.

 

[87supraturbo19]

ya i know but i have read by nick m. that the best way to check the air flow side of the sensor is by the frequency not just the volts. unless i concluded the write up wrong. please clarify.

 

[2543arvin]

ya i know but i have read by nick m. that the best way to check the air flow side of the sensor is by the frequency not just the volts. unless i concluded the write up wrong. please clarify.

No youre right, frequency is the best way, but jetjock has said that you can test with volts to get by and still be able to determine if the AFM itself is bad.

 

[cuel]

How to test the airflow meter: http://cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=FI&P=96

Resistence is measured in ohms, that funny horseshoe looking symbol.

 

[jetjock]

Yeah, you can wing it with volts. Use the values in the TRSM for guidance. Since you're measuring duty cycle even if you can't know exactly what's going on you'll know for sure if it's bad. A 10 cent LED with a resistor will do it too. Even though I'm not a fan of the resistance method you can also do as cuel said and try it.

The code is already telling you the signal is bad. What you have to find out is if it's the sensor or the wiring. Be sure to test the 5 volt part of it. Forget about the air temp part, it's not what is giving you the code. That leaves 3 pins. One will be ground, one 5 volts, and the other Ks.

i am on my last leg with the supra i cant make any mistakes or she will cut the other one off. i will still have the supra but no legs to drive it.

Yet another thread that reminds me why I went out of my way to marry a foreigner....