Testing the cam position sensor

[free_couch]

Lately my supra has been not starting when hot, it cranks fine, just wont fire up, and after it cools off it will start right up again. After reading some different posts, I decided to start by testing the cam position sensor. The factory manual says that the maximum amount of resistance allowed for each of the three pickups, (G1, G2, and NE) in the cps is 180 Ohms. I first tested the cps a couple of hours after I had driven it, and the resistance for each pickup was about 177-180 ohms. Then I drove the car again to let it warm up, and when I checked the resistance again, all three terminals were above 190 Ohms. So my question is, because the manual is vague on this, does the specified resistance of 140-180 ohms only apply when the car is cold, or is the cps never supposed to have a resistance measurement of over 180 ohms?

Thanks!!!

 

[Zumtizzle]

Hi fellow sactown member.

usually when you have these problems, it tends to be the vsv for the fuel pressure regulator.

that vsv ups the fuel pressure and allows the car to start when hot.

 

[free_couch]

Hi fellow sactown member.

usually when you have these problems, it tends to be the vsv for the fuel pressure regulator.

that vsv ups the fuel pressure and allows the car to start when hot.

I didn't think it was a fuel problem because i have a gauge on the fuel pressure regulator, and it had good pressure. Does the good pressure reading matter if the vsv is the problem?

 

[Zumtizzle]

is fuel pressure higher when the motor is being cranked when it's hot?

and few a few seconds after, IIRR.

Regarding the resistance of the CPS, you may want to remove it and check clearances of the pickups.

 

[free_couch]

I don't remember the fuel pressure being higher, thanks for the tip, ill test the vsv. Also, i already checked the clearances of the pickups, and they seemed to be in spec.

 

[Zumtizzle]

Remember metal expands.

Those specs probably only pertain to the CPS when cold.

I'd check for you when my car is up, but all my exhaust components are ceramic coated so my ex side is pretty cool, and probably won't be the same as yours.

I'm hoping JetJock chimes in on this thread, he tends to know definitive answers on questions like yours.