Hemi Dodge 114

[antus]

Yeah stall will be no speed sensor. You need to adjust the butterfly on the TB so that its slightly more open so there is enough air coming in to keep it running as it cant tell if your idling or not.

[briney]

ok. thanks. i rang up flexible drive agencies and they had an inline hall effect pulse generator. it apparently puts out 8 pulses per turn. i'm not sure how that converts to pulses per km. does anyone know how to work it out ?

[antus]

Trial an error. Use a GPS on a phone, or a real one, drive along and calculate the % difference from the GPS vs what your logging from the ecu. Adjust the PPK value in the ecu by the error % and you should be dead on.

I think you can also use a VS/VT ABS sensor, and mount it anywhere after the trans where it'll see metal spinning past it. Im planning on doing this on a datsun 240z delco conversion. Going make up a little mount on the diff to hold the sensor and bolt some notched flat metal about 4mm thick on the front of the diff and try to use that to sense speed. Not sure how well it'll work yet, but I think it will.

[festy]

I've used sensors pointing at the back of wheel hubs for roadspeed input before, lined up so it sees the heads of the wheel studs.

[briney]

the main bonus with the sensor i looked at is it is hall effect. aren't the abs wheel speed sensors a sine wave ac deal ? or could you use something like a camira module to convert ac to square wave ? or lay off the crack pipe ?

[antus]

AFAIK Sine or square wave is fine. But maybe VL400 can confirm?

[VL400]

Square only on the 808 but yeah any reluctor amp would work or could even use a small circuit using an op-amp for a basic conversion - its not critical like a crank pickup.

The PPK value is worked out as follows...
Pulse/k = (1000/Tryw Circ in m) * Diff Gear * PPR

Standard VN setup is 4 PPR, 3.08 diff and 1.98m rollout = 6222 (they had a divide by 5 box so the factory cal is 1250PPK).

[antus]

Thanks for that, added to the FAQ.

[festy]

its not critical like a crank pickup.

I don't suppose a hall effect sensor works as a crank pickup with a DIS module?

[VL400]

Most likely not, the IC in the modules I have tried are zero crossing detectors so need a voltage that passes through 0v to trigger. Same goes for the VR auto PCM, cant trigger the reluctor VSS input with a positive only square wave