Crank trigger EFI help

Can you get the pickup sensor in there........does your efi system use the 36-1 input

In honesty the system won't care where the trigger wheel is mount......which is why some are at the rear of the engine, some are in the middle, some are under the dampner. What matters is can you get a sensor to it, can you get the pickup angle correct, does your software support the pickup input your using

 

I'm using MS3pro. It has multiple options for crank trigger. The hall sensor bracket will bolt to the unused fuel pump location.

 

Read the manual or Google. Ideally its adjustable in the software. I just want to call out the missing tooth phasing is in relation to the sensor, not timing mark on the balancer.

I lined up the balancer on the 0° timing mark then rotated the missing tooth three teeth (~30° on a 36-1 wheel) past the sensor. So the missing tooth will pass the sensor ~30° before TDC. It'll be close enough to start the engine, lock the timing at like 5°< then adjust the trigger angle until it matches the timing light.

 

That is a slightly better way to word what I was trying to say about reference angle its what the ecu will see, not what you ignition timing output will be. And as stated once running you will need to verify and adjust to make sure what timing the computer is calling for is actually what your are seeing with a light

 

That makes a little more sense. When you lock the timing down, you can set it in the computer, then check to see with a timing light where im at. Then i can adjust the angle the sensor is at to bring whats input on the computer screen and whats seen on the timing light together?

 

Ive never messed with EFI before let alone a distributorless set up with multiport injection. I think (possibly) im starting to understand this very little by very little

 

Yes you need to verify you actually timing and what the computer thinks it are the same...

Are you running this distributor less?? Cause that's a totally different animal.

I've never built a distributor less setup b4.........but done chevy sbc and bbc with distributors........and you test lock the computer to say 20........you need to verify and adjust your distributor to be at 20...........if you read say 15 your timing will always be 5 behind......and same if it's high

 

The megasquirt lets you adjust the angle in the software. Set the physical sensor in place and leave it alone. Get it fired up, lock timing (command 5° so its still on the timing tab), adjust the trigger angle number in Tunerstudio up or down until it matches the timing light. I imagine Holley is similar, but I've never used a Holley EFI system.

 

I would imagine the tuning software is similar. I would have to open the holley software and see what all adjustments they have in them.

Yes i believe this is a distributorless set up. I have the GN sensor in place of the distributor, with coil pack over plug ignition

 

Here's an extremely crappy video I made 14 years ago showing once the trigger angle was set in the Megasquirt I could command about any timing, and I used 50° as the example.

If you immediately pause it, you can see my trigger angle is set to 11°, and a fixed 50° commanded. This was before my crank trigger and was a modified hei, that's why its 11° and not like 30°.

 

Did you set the 11° randomly? This way you could see you could command any timing. So with that setup you could input the 11° offset and the system would time itself accordingly? Then you checked it with the light to make sure that was the timing you were seeing

 

This is the holley input for the crank sensor in their tuning software. I dont have the tune that was given to me in the software yet, i just wanted to look around in the program and see what all i had access to

 

Greg, the tune that’s in the ECU should be close enough that you can run your engine safely until you get it on a chassis Dyno. The only thing that you would have to change is that if your cam does not have a 4-7 firing order swap. Mine did.

 

Not random, I estimated I physically set the pick up to 10°, so I set the trigger angle to 10°, fired the engine up and the timing light was showing 1° off commanded, so I went to 11° and the timing mark matched commanded. I usually command 5° or 10° on first fire up to keep the timing mark on the factory timing tab. Then I got silly and commanded 50° just to see if it'd accurately time up to that, which it did.

 

I remember you telling that to me now Tom. Yeah i just have to swap the 4-7 for that tune to run it. I just want to see where i need to put the trigger wheel when i install the new wheel. Want to make sure i can install the new one correctly

 

But again. You wouldn't be able to command 50*btdc if the actual pick up wasn't at least that far ahead.......the ecu can not predict when the next trigger event will occur. So say if you have your sensor located in a position that it sensed the wheel passing by at say a true physical 25* btdc........you could command 50 but never truly see it.........if you want 50* the sensor has to read that trigger event happening b4 50*.... the ecu can only adjust timing by altering the time between when it picks up the trigger and when it fires the coil/injectors. More delay would equal less time or lack of advance..........less delay would equal more advance. But it can't advance so far its firing b4 it sees the pickup. So make sure your wheel triggers your sensor at a location so advanced you will never need that much timing.

Phasing or syncing the command 10, 15,20, whatever to what you see on the timing cover is different and not sure how you would sync them on a DIS setup........

 

Huh? The ecu does predict when the next tooth should arrive and calculates the crank angle between the trigger and predicted trigger. The megasquirt will give a fault code if the tooth shows up outside an expected prediction. Then on top of that the ecu gets multiple updates of crank location throughout the crankshaft rotation. It gets a update every tooth, or 10° of rotation, and its very easy for the software to pretty precisely calculate when the next tooth should arrive and time to crank angle relationships. Even with the hei only having 4 pick-ups per crank rotation, the computer is calculating and adjusting in millisecond time. So the software just needs to know the rotation angle between TDC and the reference tooth to make the math work. It always doing the math for the following crank rotation, so any timing commanded is possible on a distributorless system and any timing allowed by the physical rotor phasing in a distributor system.

 

So inthis example it gets a pulse evey 10* and then the missing tooth signal 1 time per revolution......but it can't predict when it will be there.....the ecu doesn't know if the engine is speeding up or slowing down. This is why a 36 tooth wheel is better than a 4. And why a 52 is better than a 36......its physically mote information for the ecu.

But the ecu can only react to input.......

So let's say the missing tooth signal is the main input........which it of course is....the ecu can not predict when exactly the next missing tooth trigger should be there........it uses the other 35 pulses to give it fill in information so it knows if it holding rpm......slowing down.......or speeding up. but that's not predicting. And it doesn't know the difference between the other 35 inputs without help from another sensor till it see the missing tooth. If the ecu could predict based on just the crank sensor it wouldn't need the cam sensore at all.

 

Again, huh? Its using derivative calculus to predict what the engine is doing between teeth based on the time changes between the previous teeth. It does know if its accelerating or decelerating and always has a predicted time for seeing the next tooth. If it doesn't see it in the predicted time then an error code is given. OEMs do this, Megasquirt does this, and I'm sure Holley does as well.

It only needs the cam sensor to know if #1 is on the compression or exhaust stroke. In Megasquirt, you can unplug the cam sensor after start up and it'll continue running in full sequential mode because it just uses the cam sensor at start up then remembers in the math what stroke each cylinder is on. Even then, it'll run just fine without the cam sensor in semi-sequential mode.

 

So if the ecu could predict exactly everything perfect and actually like your saying then you would only need a wheel with 1 pickup/trigger point. From there it would exactly know the complete rate of accusation and deceleration........it can't. Hence why we have wheels with 20,30,50ish teeth.

It uses all those PAST inputs. Like any computer the more information in the better it is.......there is no way a system with a 1x trigger would run as well as 36x or 52x trigger. Yes it would run on a 1x. But by the time it came back around is figures would be off and it would readjust.........it can't know the future exactly........it can assume, but it can't predict exactly. It uses the the more inputs to adjust more actually