At my wits end... ANY IDEAS? LS3 with 24X trigger.

[nathaninwa]

This is exciting. I wonder is making a stiffer sensor bracket or making something with the body hole to make it solid would help with the sync loss

[billr]

My guess is that "side-looking" config has the sensor too close to the crank right now. Try moving it out a bit. What air gap do you have now?

[DLRacing]

This is exciting. I wonder is making a stiffer sensor bracket or making something with the body hole to make it solid would help with the sync loss

Just as a test I may cut a piece of hard rubber to wedge between the connector and the angle aluminum to dampen any possible vibrations.

Thanks,
David

[DLRacing]

My guess is that "side-looking" config has the sensor too close to the crank right now. Try moving it out a bit. What air gap do you have now?

That's what I suspect as well. It could be on the verge of picking up the bottom of the slots.

I had the air gap at .012" when I first started it, but was concerned that the wheel could hit the sensor due to thermal expansion as the block and the bracket warmed up, and also crank end-play.
I adjusted it to .018" before I drove it.

Thanks,
David

[billr]

It dawned on me that there is a subtle, but maybe big, difference in how that sensor is oriented in the first ("radial") and second ("axial") configs. In the radial one the target (tooth tips) pass across the sensor face fairly perpendicular to the axis of the "tail" defined by the electrical connector/cable. In the axial config, the target (tooth faces) passes at about 45* to the tail.

Point is, if this is a Hall sensor with just one Hall device in it, then that "clocking" of the sensor body probably won't matter. However, if it has two Hall elements, like many of the Allegro gear-tooth sensor chips, then direction of target travel has to be correct. It may be that your radial config has the sensor body rotated 90* away from where it needs to be, and doesn't have much chance; and that the axial one, being rotated 45*, isn't perfect as it needs to go another 45*, but has a far better chance of reliably detecting the wheel teeth. I don't have time to explain better this morning, but you can take a peek at an Allegro datasheet. Or, just try rotating the radial one 90* on the axis of its body so that the tail points side-to-side instead of front-to-rear.

[DLRacing]

It dawned on me that there is a subtle, but maybe big, difference in how that sensor is oriented in the first ("radial") and second ("axial") configs. In the radial one the target (tooth tips) pass across the sensor face fairly perpendicular to the axis of the "tail" defined by the electrical connector/cable. In the axial config, the target (tooth faces) passes at about 45* to the tail.

Point is, if this is a Hall sensor with just one Hall device in it, then that "clocking" of the sensor body probably won't matter. However, if it has two Hall elements, like many of the Allegro gear-tooth sensor chips, then direction of target travel has to be correct. It may be that your radial config has the sensor body rotated 90* away from where it needs to be, and doesn't have much chance; and that the axial one, being rotated 45*, isn't perfect as it needs to go another 45*, but has a far better chance of reliably detecting the wheel teeth. I don't have time to explain better this morning, but you can take a peek at an Allegro datasheet. Or, just try rotating the radial one 90* on the axis of its body so that the tail points side-to-side instead of front-to-rear.

Good point Bill, I understand what you're saying.

The original sensor I had, way back before switching to this wheel, was for the GM 24X wheel, which was a double row wheel. It is a dual sensor, and I see how clocking of the sensor would be critical.

The sensor I'm using now is for the GM 58x wheel, which is single row, and has only one Hall sensor inside.
That said, my first bracket had the sensor clocked 180* from how it would be in its normal location. I wouldn't think that the direction the teeth were moving would make any difference in the sensors ability to read them.
My current bracket does have it clocked about 15* or so, but being this is a single sensor I wouldn't think it would make any difference.

I just adjusted the sensor out from the crank centerline about 1/8", and also increased the gap to .038", as the sensor had made light contact with the wheel, due either to the crank endplay or vibration of the bracket.
I added a rubber cushion between the bracket and the sensor body for now, to see if that dampens any vibration of the mounting tab.
Going for another test drive shortly.

Thanks,
David

[Raymond_B]

Clearly you have the fab skills, why not just make a bracket for a Cherry hall sensor from DIY and be done?

https://www.diyautotune.com/product/hal ... on-sensor/

[DLRacing]

Clearly you have the fab skills, why not just make a bracket for a Cherry hall sensor from DIY and be done?

https://www.diyautotune.com/product/hal ... on-sensor/

Because I can use this sensor when I switch to the GM 58X wheel, when I refresh the motor in a year or so.

[Raymond_B]

Gotcha, I guess I was thinking you already had the DIY wheel so might as well use a known good and compatable sensor with it. 40.00 for quite a bit less frustration

I am LS dumb, can you not use the 36-1 wheel and sensor on the new motor?

[DLRacing]

GM puts the wheel at the back of the block, ahead of the flywheel flange.
Mine currently has a 24X in there, which is warped and was causing the original sync issues.

I'm not ready to tear it down yet, as I have other projects, but wanted to be able to drive it this summer, so I decided to add the 36-1 wheel as a temporary fix.
Getting it to work with this sensor assures me I'll have fewer troubles when I switch.
Total cost of this fix was a bit over $200, and I can use the $50 sensor later.

Thanks,
David

[DLRacing]

Test drive went well. I noticed no sync losses other than one during cranking. I can live with that.

Somehow my required fuel had gotten reset to 6.7. When I recalculated it went to 13.3.
I rescaled the VE table to 50%, and those numbers have a lot more headroom now.

I finally have it rich enough to get on it a bit. I think it's going to be strong when fully tuned.

[billr]

I'll clarify (I hope!): I'm not talking about two Hall sensors in one housing, for detecting a "dual row" wheel. I'm talking about two Hall sensors for just one wheel and output. They are set up so the trigger tooth passes first one, then the other in a specific sequence. I think it is used to automatically set the detection threshold, to lessen the influence of the air-gap or or variations in it (run-out of the wheel). If such a sensor is turned 90*, then the wheel teeth passes in the "valley" between the two Hall devices and triggers them at the same time, not in the sequence needed for intended operation.

[DLRacing]

I'll clarify (I hope!): I'm not talking about two Hall sensors in one housing, for detecting a "dual row" wheel. I'm talking about two Hall sensors for just one wheel and output. They are set up so the trigger tooth passes first one, then the other in a specific sequence. I think it is used to automatically set the detection threshold, to lessen the influence of the air-gap or or variations in it (run-out of the wheel). If such a sensor is turned 90*, then the wheel teeth passes in the "valley" between the two Hall devices and triggers them at the same time, not in the sequence needed for intended operation.

That's good to know.
In researching the differences between the GM 24x and 58x sensors, a member on, I believe it was LS1Tech.com, had looked up the actual components used in the sensors, and he did find that the 58x was indeed a single sensor.

The way I have it mounted now should approximate what it would have seen in it's normal application. It's only about 15* off from perpendicular, and the teeth are passing it in the normal direction now, though that didn't seem to be the problem anyway.

Thanks again. It's knowledge and experience like this that makes this forum so valuable.

[billr]

If you are curious, go to page 8 of the attached Allegro datasheet. I'm not saying that GM 58X sensor must be like the Allegro, but it might be.

[DLRacing]

If you are curious, go to page 8 of the attached Allegro datasheet. I'm not saying that GM 58X sensor must be like the Allegro, but it might be.

Thanks.

[DLRacing]

Got a minor detail with the A/C enable sorted this morning, and took it for another test/Autotune drive today.
I keep trying to get it into as many cells as I can, then go into the table and fill in the gaps.
It's running better with every session, and it was nice to be cool while tuning today.

I pulled the nose off this afternoon to make a bracket and mount a fan on the oil cooler. I wanted to get that done before I drop it off at the dyno shop where the real tuning will be done.

I'm hoping to see over 550rwhp on pump gas, but the local guy has a Dynacom eddy current dyno, which is great for tuning, but not much for bragging rights. Most say they give 10-20% lower power numbers than the Dynojet inertial dynos. We'll see where it ends up.