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?

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

Thanks for the correction.

I hate to do it, but I may pull the harness out and try and build a brand new shielded run of wire for this. Anyone know where to buy new CAS plugs and pins?

Here is a good source from an active forum members business:
http://www.lms-efi.com/sunshop/index...ct_detail&p=93

^awesome! Thanks!

the CAS sensors are really robust, but the harnesses get funky. i've also had problems with the CAS connectors being in poor shape.

I left my old cas wire as part of the harness at got Chris at LMS-efi to make me this new flying lead for the CAS for like $20-$30 and it fixed my cas issue
Attachment 638650

I just have this wire running through the firewall to the CAS until i redo my wiring.

Does anyone know what the sensors are supposed to OHM out at? Trying to determine if it's sensors, wiring, or ECU.

its in the shop manual Foxed.ca - Mazda RX-7 Manuals

ideally you wanna try it cold and hot, although its not easy to do that

Best bet on a mag pickup is to use an Oscilloscope to see if you're getting a clean/smooth sine wave.


-David Guy

Its 950-1250, however it wasn't the wiring, ecu or the sensors. It was the ground wire by the ecu. It wasn't very tight.