how do i remove this?

[spades_gsx]

my cousin bought a 98 gsx about a year ago. the car ran fine then him and I were installing some gauges and under the console we noticed something that looks like a little motor spliced into a wire coming off the ECU. He turned the knob not knowing what it was and that was that. A couple days later he got on the gas and the car started to mis bad and it was very lean and threw a RANDOM MISSFIRE code. We changed everything that could possibly cause a missfire still no dice. He took the car to the dealer and they found nothing. He took the car to AMS and they found a 1g cam sensor on his 2g head. that little motor with knob is a potentiometer and this is what is causing the problem. Itis set to run to lean. Basically to make a long story, can we remove this thing or do we have to replace the 1g cam sensor with the a 2g sensor. what would be the best way to fix this problem? and what would be the affects of removing the potentiometer with out changing the sensor?

 

[huafist]

The potentiometer is there to prevent the random misfire CEL. Turn it all the way counter-clockwise and start the car. If it won't start or is rough you turned it the wrong way. Drive it around and if you get a CEL, then add more resistance with the POT. Repeat until the CEL goes away.

The CEL does more than be annoying, it'll throw the car into limp mode. That's why it's good to have this.

 

[spades_gsx]

so you are saying that i can keep the potentiometer I just have to mess with it? is it a common mod? this is the first i have heard of this to actually "tune" with. sounds like a poor mans AFC to me.

 

[huafist]

You should keep it - it'll prevent limp mode and that CEL.
It's nothing like an AFC - all it does is increase the resistance on the Barmetric Pressure Sensor so the ECU doesn't look for a misfire. It may also lean out the car a little so in extreme cases you may have to use an AFC to keep your A/F Ratio good.

It's pretty common - I think Magnus Motorsports has a writeup on their website about it.

I think the moral of this story is: "If you're not sure what it is, don't play with it."

 

[AMS Eric #2]

It leans the car out ALOT actually. Most people don't notice it as much because theyre not monitoring their fuel trims. If you turn the resistance in the baro sensor circuit up enough to keep the ecu for checking for misfires, it will lean the car out enough for the ecu to have to max the fuel trims out trying to keep it stoich at idle and part throttle. The fuel trims will always be all over the place after doing this because its no longer actually making compensations for barometric pressure changes.

The only real solutions for this is a DSMLink, standalone ems, or keeping the seperate sensors. Everything else will be a band-aid that will always have, at best small quirks.