Ignition Sensor Differences?

[econnor]

I thought of posting this in the electrical section but this is realy pertains mostly to Evo engines.

Cam position sensors, I have three different units in my garage, all with different part numbers and they look very different from each other.

They all are built on the same aluminum plate, but the earlier one has a small, rounded rubber bumb. Wheres the later units are more squear and boxy looking. I cut one of the newer units open and it has a computer chip inside.

- What does the computer chip do?
- Besides the end connector, are the units interchangeable?

I put a DTT external ign module in my bike and the instructions call for the earlier sensor. So before spending like a $100 on a new one I would like to know more about these.

-Ed

[springer-]

The computer chip could be anything. I have never actually taken one apart to see what it is or does but a guess would be something as simple as a opto isolator or a Schmitt trigger to clean up the signal. As for the differences in look, it could be the very early model vs a latter model. The early models (shovelheads) used a different manufacture for the ignition modules and this could be the difference you see. Also the early models used an aluminum cup with a optical sensor and the later models used a steel cup with hall effect sensors. Many of the aftermarket ignitions require the steel cup.

As for your specific question about the DTT, sorry I can't help with that.

[econnor]

Springer, as usual your posts are always very informative and appreciated.

My question is not specific to the DTT module. Although I did talk with someone at their tech line, that although unable to answer my question about the differences in modules, they did say that their module would not work correctly with the newer computer chip module.

The side by side comparisons on the engine side of these sensors is very interesting. The older (-83) sensor has one sensor point on the back. While the newer ones have 2 sensor points.

My FXR has a DTT external module and my Softail has a Hi-4E module but for whatever reason I used the newer sensor with both bikes.

My FXR is being tuned by a big name race shop and they pointed out that I had the wrong sensor for the DTT module, which has me thinking about the sensor in the softail. The sensor in the FXR has been replaced by the guys at the race shop doing the tuning.

If anyone knows anything about these sensors, please chime in.

Mods: I posted this in the Evo Tech Forum because i thought it was most relative to the EVO engines. But please move to the electrical forum if you think it belongs there. I wasn't sure which forum was best. -Ed

[springer-]

Originally Posted by econnor

.....The side by side comparisons on the engine side of these sensors is very interesting. The older (-83) sensor has one sensor point on the back. While the newer ones have 2 sensor points.....

This being the case, and not having them in front of me to compare, the one with one sensor would have a cup with 2 cutouts. Each cutout would represent the firing of the cylinder at the correct time. The one with 2 sensors would have a cup with only one cutout and would fire the cylinders based on the sensor. Both systems are a dual fire system and fired both cylinders every time.

If I am not mistaken, the -83 was optical based (used a light in the sensor).

This is all speculation of course, not having tested them to confirm but I do I have a fair amount of background in cone engine style ignition modules and design.

[econnor]

But they both use the new cup. Weird.

[econnor]

I talked with the PHDs at the local dealership, they had no idea what the differences were. One of the PHDs embarrased himself when he said it was because of the MAP sensor, then retorted to claiming the VOES. Whatever.

After digging through factory shop manuals for various years here is what I have found:

- the early sensor costs much less than the newer sensor, $68 vs $145.
- in the parts manual the early sensor is simply called sensor.
- the newer unit is called sensor with attitude adjustment
- the 96 softail shop manual describes the attitude sensor as a tip over switch, bike tips over engine shuts off.
- the earlier sensor has a greater range of rotation.

I am still not sure what the chip in the newer sensor does. Seems like overkill for a tip over sensor.

I bought a new earlier sensor from the dealer. Couldn't believe they had it in-stock. After putting in the new sensor, setting the timing with a dial back light, and going for a test ride. I think the engine runs better, but that could just be the old washing the car syndrome.