Bad CAS Sensors?
09-08-14, 01:18 AM
#1
Bad CAS Sensors?
Trouble shooting a new FD build.
PFC
Streetported block 115psi on all faces
ID 1000 Primaries
ID 2000 Secondaries
400lph AEM fuel pump
Large garrett turbo(forgot specs)
E85
Stripped down EFI harness(no solenoids, just main sensors)
GM 3bar
During trouble shooting, I've verified injectors are working, TPS is set perfect,getting spark, vac lines simplified to just Map, boost, and FPR
As for the harness, I stripped it down and tested all wires for continuity and low ohm resistance. I made sure the shielding was still on the CAS wires. Although by factory, they are bare for about 3-5 inches at the CAS sensors. So I doubt it's EMI.
Initially I had issues starting the car. No ignition signal was coming out with the PFC. The stock ECU saw trigger signal but not PFC. I shimmed the CAS sensors 1mm away from the trigger wheel and it started up but was VERY rough and lumpy. The PFC would read 500 rpm while the tach was at 900. At 3500, it was off by 1k rpm.
Today I shimmed them so they are 1/3-1/2 mm away from the trigger wheel. The Tach and PFC now are identical in rpm and the car revs MUCH better. It free revs and doesn't back fire. Although now we have the idle hunt around 1500 rpm.
Could the CAS sensors have gone bad? How can I test them? I'm wondering if they have internal resistance making the Hall effect field smaller which makes the closer proximity needed to read signal?
PFC
Streetported block 115psi on all faces
ID 1000 Primaries
ID 2000 Secondaries
400lph AEM fuel pump
Large garrett turbo(forgot specs)
E85
Stripped down EFI harness(no solenoids, just main sensors)
GM 3bar
During trouble shooting, I've verified injectors are working, TPS is set perfect,getting spark, vac lines simplified to just Map, boost, and FPR
As for the harness, I stripped it down and tested all wires for continuity and low ohm resistance. I made sure the shielding was still on the CAS wires. Although by factory, they are bare for about 3-5 inches at the CAS sensors. So I doubt it's EMI.
Initially I had issues starting the car. No ignition signal was coming out with the PFC. The stock ECU saw trigger signal but not PFC. I shimmed the CAS sensors 1mm away from the trigger wheel and it started up but was VERY rough and lumpy. The PFC would read 500 rpm while the tach was at 900. At 3500, it was off by 1k rpm.
Today I shimmed them so they are 1/3-1/2 mm away from the trigger wheel. The Tach and PFC now are identical in rpm and the car revs MUCH better. It free revs and doesn't back fire. Although now we have the idle hunt around 1500 rpm.
Could the CAS sensors have gone bad? How can I test them? I'm wondering if they have internal resistance making the Hall effect field smaller which makes the closer proximity needed to read signal?
09-08-14, 01:42 AM
#2
Trouble shooting a new FD build.
PFC
Streetported block 115psi on all faces
ID 1000 Primaries
ID 2000 Secondaries
400lph AEM fuel pump
Large garrett turbo(forgot specs)
E85
Stripped down EFI harness(no solenoids, just main sensors)
GM 3bar
During trouble shooting, I've verified injectors are working, TPS is set perfect,getting spark, vac lines simplified to just Map, boost, and FPR
As for the harness, I stripped it down and tested all wires for continuity and low ohm resistance. I made sure the shielding was still on the CAS wires. Although by factory, they are bare for about 3-5 inches at the CAS sensors. So I doubt it's EMI.
Initially I had issues starting the car. No ignition signal was coming out with the PFC. The stock ECU saw trigger signal but not PFC. I shimmed the CAS sensors 1mm away from the trigger wheel and it started up but was VERY rough and lumpy. The PFC would read 500 rpm while the tach was at 900. At 3500, it was off by 1k rpm.
Today I shimmed them so they are 1/3-1/2 mm away from the trigger wheel. The Tach and PFC now are identical in rpm and the car revs MUCH better. It free revs and doesn't back fire. Although now we have the idle hunt around 1500 rpm.
Could the CAS sensors have gone bad? How can I test them? I'm wondering if they have internal resistance making the Hall effect field smaller which makes the closer proximity needed to read signal?
PFC
Streetported block 115psi on all faces
ID 1000 Primaries
ID 2000 Secondaries
400lph AEM fuel pump
Large garrett turbo(forgot specs)
E85
Stripped down EFI harness(no solenoids, just main sensors)
GM 3bar
During trouble shooting, I've verified injectors are working, TPS is set perfect,getting spark, vac lines simplified to just Map, boost, and FPR
As for the harness, I stripped it down and tested all wires for continuity and low ohm resistance. I made sure the shielding was still on the CAS wires. Although by factory, they are bare for about 3-5 inches at the CAS sensors. So I doubt it's EMI.
Initially I had issues starting the car. No ignition signal was coming out with the PFC. The stock ECU saw trigger signal but not PFC. I shimmed the CAS sensors 1mm away from the trigger wheel and it started up but was VERY rough and lumpy. The PFC would read 500 rpm while the tach was at 900. At 3500, it was off by 1k rpm.
Today I shimmed them so they are 1/3-1/2 mm away from the trigger wheel. The Tach and PFC now are identical in rpm and the car revs MUCH better. It free revs and doesn't back fire. Although now we have the idle hunt around 1500 rpm.
Could the CAS sensors have gone bad? How can I test them? I'm wondering if they have internal resistance making the Hall effect field smaller which makes the closer proximity needed to read signal?
The sensors aren't Hall Effect, they're mag pickups. The sensors tend not to go bad, but the harness does. Also confirm that you don't have them backwards (doubt it since you're able to at least get the car started but you never know.)
-David Guy
09-08-14, 03:42 PM
#6
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the CAS sensors are really robust, but the harnesses get funky. i've also had problems with the CAS connectors being in poor shape.
09-08-14, 06:41 PM
#7
Here is a good source from an active forum members business:
RX-7 93-02 CAS Connector
RX-7 93-02 CAS Connector
I just have this wire running through the firewall to the CAS until i redo my wiring.
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09-13-14, 09:47 PM
#9
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ideally you wanna try it cold and hot, although its not easy to do that
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