Un-connected Bosch FI Pressure Sensor

[mighty7]

Does anyone know why I have a Bosch fuel injection pressure sensor on my 1985 Pininfarina Spider Azzura that is not even hooked up? Should it be hooked up? Could it be hooked up? Is there even a connector on the FI cable harness for it? Shouldn’t the computer use information from that sensor to adjust the mixture when I drive into the mountains or on a cold day, etc?



Thanks, Scott

[RRoller123]

hmmmmmmm.... my 80 FI doesn't have one of these.

[GeorgeT]

I believe that is an atmospheric pressure sensor. Not sure how it is used; my '82 did not have this.

[Tobi]

That is an altitude sensor for 84 and 85 spiders. Could be the hook up was optional. I think in some Lancias they came in a bag in the glove box. That would make sense to have that installed in northern California.

[mighty7]

Does that mean my fuel injection harness is not from my 1985 since there are no harness points to go to it?

[ga.spyder]

I am pretty sure that has nothing to do with your fuel injection.

[majicwrench]

That is indeed a altitude sensor. I would let sleeping dogs lie, assuming car runs well now.
Keith

[Tobi]

http://www.autoricambi.us/product/FI1-4 ... OEM-Bosch/

[ga.spyder]

Keith,what is its purpose,and is it connected to the F.I. system? Just curious,I have never seen one.

[BEEK]

on the 83 and later spiders the injection system had the altitude sensors installed. if your harness does not have a place to connect it, then i agree that someone has changed your harness. your car will run just fine without it

[ORFORD2004]

None on my 83

[mighty7]

so anyone know where to get a new FI harness for an '85?

[FiatMac]

Keith,what is its purpose,and is it connected to the F.I. system? Just curious,I have never seen one.

Craig,
The altitude sensor corrects the fuel injection system for the loss in air density with altitude. The L-Jetronic air flow meter measures air volume entering the system. However, a mass flow is required to get proper air fuel ratio (Air Fuel Ratio = Mass of Fuel/Mass of Air) so air density is needed. The electronics in the ECU are set up with fixed density. This has little effect unless you have large swings in altitude. The '83 and higher ECU uses the altitude sensor to make the correction. Air pressure decreases with altitude which results in a density decrease. The sensor output varies with atmospheric pressure. The output signal is fed to the ECU to adjust the fixed density in the hardware.

When the engine is running where the O2 sensor is correcting the mixture, the lack of an altitude/barometric pressure correction is not a problem. The issues will be at idle and wide open throttle. Without the correction, the system will run rich at high altitude or low barometric pressure since less air mass is supplied at the measured air volume. Since running rich at wide open throttle is on the safe side, and may even be desirable from a power standpoint, wide open throttle is not a particular issue. There likely would be some rough idle issues.

The sensor probably was added to address the idle issues and emissions requirements.

[majicwrench]

Good explanation.

[ga.spyder]

Thanks,Stan