gm sensor architecture/compatibility info needed

[dohcfiend]

i am back in the process of retrofitting a 98 n* tb on a 96 dohc. i have most of the planning covered(i believe anyway).

well it helps that i am having some1 fab up a new tb neck to match the tb since i am not equipped for that level of fabrication.

only 2 areas i am not 100% on yet are the iac and tps on the n* versus the 3.4 dohc. this is just a guess but i think the iac might function the same way. all it is is a stepper motor(correct?) as long as it functions off of 12 volts i think the computer will be able to handle the different iac.

the tps operates off of 5 volts and i think all it is an adjustable resistor. where the resistence changes in conjunction with throttle angle?

but i think if bad came to worse i could rig the dohc tps to the n* tb.

another area i am unsure about is the amount of rotation from 0-100% throttle plate position difference and if there is any between the n* throttle plate and the dohc plate(i would guess there isn't any or if it is, it will be marginal) . if the amount of rotation is the same then rigging the dohc tps will be no sweat(if i even have to)

any input would be appreciated. thanx.

[Juglenaut]

Yes the IAC is a 12 volt stepper type, but it also requires a 5 volt binary reference I think it is 1,1> 0,1>1,0 for input (the value might be different) to move across its travel and the IAC also has a step counter in the ECM for when it hits 1,1 counts as a one sequence and a set number of sequences equal a revolution, I think GM's are most likely 2 seq to one rev. An IAC with a different input variable will not work, must be the same as or reversed which then can be inverted before the IAC.

of course you can make any IAC work you just need to know the sequence that it requires and uses inverters or gates to change the input from ECM, just make sure you put the step counter at the beginning or end not that it really matters much. Most IAC's are a ECM driven perhiperial with a set instruction and sends no information to the ECM, the EMC will fault it if no current is on the referance, the supply voltage, out of parameters, and other sensor faults can cause IAC to false fail.

I can't remember if GM IAC's are 4bit or 8bit sequence (2 input or 3 input binary). logic 0,0 is a default return on all steppers but still is considered a bit.

TPS's are in referance to ground where the center lead going to the ECM this is where the calibration comes into play, one of the side leads from 5 volt reference ECM, one side leads to ground these goto the ECM for non floating points. The ECM doesn't measure resistance so to speak, but where the tap (center lead) is at in respect to 5 volts and ground or logic zero. An op amp references this at a set value of voltages and is used to run other functions like fuel enrichment I would think.

[dohcfiend]

i might be ok. not sure though. some1 else put a ls1 tb on a dohc and he said they both functioned np. but i will see.

[Juglenaut]

I don't think there would be a problem since the travel is the same 90 degrees to full open.