Ford_Forgotton
Full Access Member
Just when you thought you couldnt add any more guages to your truck.
With a little help from Scott at www.boyercustomtruck.com , we did some snooping and discovered that Autometer 0 to 100 PSI electric fuel pressure gauges can double as HPOP gauges.
The reason for this is, the sending unit that came with my cobalts has the same electrical plug as my ICP sensor (used by the computer to determine HPOP pressure and adjust IPR duty cycle).
So, to test my theory, Scott went out and plugged his autometer cobalt fuel pressure gauge into his ICP and would you believe it, it worked! At idle his truck read about 18psi on the gauge, and if he did a snap throttle, it would jump up to almost 80psi. At wide open load on the road, it would go to 70-75psi and hold steady (late model hpop on a 97 truck, so plenty of oil for him)
The math I did earlier in the day said it should have read about 13psi at idle and max out at about 60-70psi. I figured it was a "times 40" multiplier, so 10psi would be 400, and 60psi would be 2400.
He did have his real ICP wire disconnected so, his truck my have been in default mode for IPR and the readings we got are slightly off, but the base idea worked!
That gives me two more options.
1. Tap the signal wire on the factory ICP sensor and run it to the gauge. It will display what the computer is seeing. Cheap and easy.
2. Buy a second ICP sensor and screw it into the 5 other available ports in the heads (3 if you have an HX hose kit installed). Now you can run a 10k mod on the REAL ICP, but still get accurate pressure readings on the gauge in the cab.
The only catch is to get gauge faces made up that match the pressure readings. Something autometer should have no problems doing if there is enough demand.
DO NOT USE THE SUPPLIED SENSOR THAT COMES WITH THE GAUGE!!!!!
You have to use the ICP sensor. Its the only one I know of that is rated to handle the "up to" 4000psi in the heads. Its also calibrated internally to that high of a pressure. 2.95 volts on the autometer sending unit is only like 60psi, whereas its closer to 2000psi on the ICP sending unit.
The 0 to 100psi boost gauges seem to work also, as again, they have the same electrical plug, and use the same 0 to 5v signal voltage, so the gauge calibration is already there, its just a matter of getting the needle markings to match the real pressure numbers, instead of having to do math in your head.
Im kinda suprised no one has tried this yet, its so easy in hindsight, but then, most things are.
With a little help from Scott at www.boyercustomtruck.com , we did some snooping and discovered that Autometer 0 to 100 PSI electric fuel pressure gauges can double as HPOP gauges.
The reason for this is, the sending unit that came with my cobalts has the same electrical plug as my ICP sensor (used by the computer to determine HPOP pressure and adjust IPR duty cycle).
So, to test my theory, Scott went out and plugged his autometer cobalt fuel pressure gauge into his ICP and would you believe it, it worked! At idle his truck read about 18psi on the gauge, and if he did a snap throttle, it would jump up to almost 80psi. At wide open load on the road, it would go to 70-75psi and hold steady (late model hpop on a 97 truck, so plenty of oil for him)
The math I did earlier in the day said it should have read about 13psi at idle and max out at about 60-70psi. I figured it was a "times 40" multiplier, so 10psi would be 400, and 60psi would be 2400.
He did have his real ICP wire disconnected so, his truck my have been in default mode for IPR and the readings we got are slightly off, but the base idea worked!
That gives me two more options.
1. Tap the signal wire on the factory ICP sensor and run it to the gauge. It will display what the computer is seeing. Cheap and easy.
2. Buy a second ICP sensor and screw it into the 5 other available ports in the heads (3 if you have an HX hose kit installed). Now you can run a 10k mod on the REAL ICP, but still get accurate pressure readings on the gauge in the cab.
The only catch is to get gauge faces made up that match the pressure readings. Something autometer should have no problems doing if there is enough demand.
DO NOT USE THE SUPPLIED SENSOR THAT COMES WITH THE GAUGE!!!!!
You have to use the ICP sensor. Its the only one I know of that is rated to handle the "up to" 4000psi in the heads. Its also calibrated internally to that high of a pressure. 2.95 volts on the autometer sending unit is only like 60psi, whereas its closer to 2000psi on the ICP sending unit.
The 0 to 100psi boost gauges seem to work also, as again, they have the same electrical plug, and use the same 0 to 5v signal voltage, so the gauge calibration is already there, its just a matter of getting the needle markings to match the real pressure numbers, instead of having to do math in your head.
Im kinda suprised no one has tried this yet, its so easy in hindsight, but then, most things are.
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