I'm pretty sure my pressure sensor is going out, but I want to confirm this.

At full atmospheric pressure, my pressure sensor (S4 NA, read via SAFC-II sensor check) is only putting out ~3.3v. This seems low, I haven't been hitting 100% "throttle" opening on the SAFC, and it seems to be outside the range of the FSM test, but I don't actually have a vaccum pump to apply the proper test with.

I seem to recall on the NAs, full atmospheric pressure should be around 4.5v or so. Is this correct?

Other than a bad sensor, are there any other common causes for low voltage here? I'm planning to get the DMM out & probe things later today (if I brought it with me) to make sure I've got the full 5v source & such. I don't have any of the standard signs of grounding issues, just the low voltage (and I think last time I had diagnostic lights on, it was complaining about the pressure sensor at high RPM)...

... and anyone have a spare S4 sensor laying around they'd sell?

-=Russ=-

 

The book says, with the engine idling and the vacuum hose pulled off and the hose plugged to prevent vacuum leaks, the sensor, the reading will be 3.5vdc to 4.0vdc.

 

Thanks. I'll look for a new sensor,then.

-=Russ=-

 

just wondering, what is the range? and is it linear?
sounds like 4.0 V is around upper range for NA operating condition, but what is lower limit (full vac)? FSM says 100mmHg is 2.8-3.2V, although i forget exactly how this compares to full vac on an NA...

 

Russ, did a new sensor actually fix this??
because i am getting 3.37v with the engine off. however the S5 FSM says that at atmosphere the pressure sensor should be 3.4-3.6v (although i do believe an S4 pressure sensor is different), so i guess this isn't too far off...i haven't datalogged vacuum yet...

 

good thing a pressure sensor will be like $10 used