No rpm during cranking, stop cranking and get rpm

[rabid]

2017-08-22_20.48.09.msq

2017-08-20_09.43.37.msl

I have had this problem for quite a while now. It took a long time to figure out when it happens and to capture a datalog of it. It seems to happen reliably if I warm up the engine for about 5 minutes and then shutoff and then come back 10 minutes later and try to start it. I crank the engine and there is no rpm. As soon as I stop cranking, sometimes an rpm is detected briefly. The battery is small and can't handle too much cranking. I was abusive to it in the logs and extended the cranking to watch gauges in tunerstudio. It did actually start eventually on a near dead battery. Normally the trick to starting it is to crank, key off, crank, key off, and usually start in 3 to 5 tries. The engine starts reliably dead cold and fully hot.

This is a hall sensor and 36-1 wheel on the cam. I wonder if there is something wrong with the starter or bad grounding or some kind of noise. I'm am sure that there is one ground wire from the ecu to the sensor. I get continuity from the sensor ground to engine ground with the ecu connected and nothing with the ecu disconnected.

Any ideas on trouble shooting this?

Thanks

[B1ack_Mi16]

Probably the same problem as me with the small battery.

Too much voltage loss so the ECU don't get 5v ++ until cranking ends. When cranking ends engine uses a tiny bit of time to come to an halt and ECU gets >5v again and picks up rpm for a fraction of a second.

I have this far just put a large normal car battery in paralell in the trunk to make the car driveable.
After adding the larger battery the problem has went away completely.

[B1ack_Mi16]

I can add that mine also actually always seemed to start fine on cold starts first time.
But after a bit of running and heat build-up when trying to restart it, it would start to behave like you describe.

I thought it should be easier to start the engine when hot compared to cold, so I never really understood the mechanism to why it acts like this, and not the opposite way around...
But as said, try to hook up a larger battery temporary and see what happens.

[whittlebeast]

Assuming you have a paid version of Tuner Studio. Create a time gauge with these steps

1) Right mouse click out between any two gauges

2) Check Designer Mode

3) Click on any gauge and <copy> <paste> to create a new copied gauge

4) Right mouse on that new gauge and pick <Dash Board Designer> <Gauge Style> <Basic Readout>

5) Right Mouse click on that gauge and pick <Calculations #> <Clock - clockGauge> the "#' will be a number. Clock should be there somewhere.

6) Left mouse click on the bottom right red dot and size that new Clock Gauge to a reasonable size

7) Left Mouse click and hold to move that gauge to a reasonable place

Now when you turn on the key, you will see that gauge start to count off seconds. Let it get to say 10 sec and then start to crank the motor. If the time keeps counting past ten, you do not have a reset issue. If you get the counter to go back to 0 and start over counting, you have wiring issues or battery issues. Weak battery and ignition key wiring are the most common.

Hope this helps.

Andy

[rabid]

Assuming you have a paid version of Tuner Studio. Create a time gauge with these steps

Andy

Wouldn't that show up in the datalogs?

[rabid]

After a few tries I got it to fail again. After a few cranks, I connected another battery and it was the same. I connected the battery to the starter motor and it fired right up. I don't know if that means anything. I moved the transaxle ground wire to a screw on the starter to see if that makes any difference. Only time and testing will tell.

[rabid]

The problem has still been happening. My next suspect is my tooth 1 angle. It's at 71.5 degrees on a 4 cylinder. I noticed that under some conditions, the piston coming up on compression causes a much longer time between teeth and the missing tooth time isn't much longer than the other teeth. I also found the recommendation to place the missing tooth between 90-120 degrees on a 4 cylinder. I refabricated my mounting and got it about 110 degrees. Now the compression stroke is helping the rpm come up and the missing tooth is just into the valley of the tooth logs and is nice and clearly defined. I have a good feeling this will solve it. Time will tell.

[rabid]

Nope, just bad luck but this seems to happen when I've trailered the car hundreds of miles and it wants to give me a heart attack by not starting on race day. Lower elevation? I had this happen three days in a row so I was able to get some datalogs. Only I wasn't able to because logging quit working. I fixed that by updating tunerstudio to 3.x. I did get the tooth logs though.
If this happened regularly, I could gather data and make changes. I'm going to change the tooth detection edge and correct the tooth one degree timing to see if that makes a difference.

The thing that stands out to me is I would expect the missing tooth to be twice as tall as the others. But during cranking it isn't.

2018-07-01_07.50.55.csv

This is when rpm showed zero while cranking. Eventually it started

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2018-07-07_17.05.31.csv

This is cranking when rpm is detected no problem. Throttle is at 100% to go into flood clear and not start.

(32.23 KiB) Downloaded 18 times

2018-06-22_20.19.34.msq

(226.76 KiB) Downloaded 17 times

[Keithmac2]

First thing I would do when it plays up is to jump itnoff a bigger battery and see what happens (as said above).

Also you can't have enough ground wires from the battery (at least one to engine block and one directly to starter motor mounting bolt).

Maybe your only option will be to have a "starter battery" which is easily removable after starting, or a light weight LiOn battery of correct cranking amp rating (light but very expensive!).

[jsmcortina]

Set ignition mode to "Log crank" and record a composite log. That will help determine if you are triggering on the correct edge. The tooth logs when the engine is running appear to suggest that it is.

If the edge is correct, then consider the following:
The compression effect is preventing detection of the missing tooth region. It isn't longer enough (in time) than the previous tooth-gap.
Are you able to change the wheel / sensor phasing ?
If you can make the missing tooth pass the sensor say 1 cam tooth later (and adjust the tooth#1 angle accordingly) then I think you would be ok.

If that doesn't work then chop off an additional tooth (later in rotation) to make it a 36-2, you'd need to adjust tooth#1 also.

James

[rabid]

Set ignition mode to "Log crank" and record a composite log. That will help determine if you are triggering on the correct edge. The tooth logs when the engine is running appear to suggest that it is.

Does version 1.3.2 firmware support log crank? I'll try it. It is a hall sensor so does it matter which edge I use? It runs fine on either setting. My new wheel settings are 112 degrees on falling edge or 101 degrees on rising edge. Both have that same somewhat-too-short missing tooth. My old wheel was set to falling edge 72 degrees which put it on the up stroke compression. It also had that same pattern of tooth but closer to the compression "peaks".

If the edge is correct, then consider the following:

The compression effect is preventing detection of the missing tooth region. It isn't longer enough (in time) than the previous tooth-gap.
Are you able to change the wheel / sensor phasing ?
If you can make the missing tooth pass the sensor say 1 cam tooth later (and adjust the tooth#1 angle accordingly) then I think you would be ok.

If that doesn't work then chop off an additional tooth (later in rotation) to make it a 36-2, you'd need to adjust tooth#1 also.

James

If the problem really is that the missing tooth time isn't long enough, I think you're right about going to 36-2. To be clear, are we trying move tooth one from about 112 degree to about 122 degrees? Tooth one is the first tooth to reach the sensor AFTER the missing tooth goes by. Correct? So cut off tooth one and recheck with a timing light and change the tooth one angle.

Could this problem be caused by RPM Averaging Lag Factor set to 10?

[rabid]

First thing I would do when it plays up is to jump itnoff a bigger battery and see what happens (as said above).

Also you can't have enough ground wires from the battery (at least one to engine block and one directly to starter motor mounting bolt).

Maybe your only option will be to have a "starter battery" which is easily removable after starting, or a light weight LiOn battery of correct cranking amp rating (light but very expensive!).

I have tried adding a battery when this happened. Normally, the battery can be pretty dead and still start the engine even at half of the normal cranking speed.

[jsmcortina]

It is a hall sensor so does it matter which edge I use?

For any input the Input Capture should normally be set to "Rising" as the input circuit is designed to work that way. This translates to a falling edge outside the box. For Hall inputs this 5V->0V edge is typically electrically "stiffer" so is the best to use, the less stiff edge will have more phase (timing) shift with RPM.

My old wheel was set to falling edge 72 degrees which put it on the up stroke compression. It also had that same pattern of tooth but closer to the compression "peaks".

I would have expected that to work better as that is a more typical angle to use. Did it ? Why did you change the wheel ?

So cut off tooth one and recheck with a timing light and change the tooth one angle.

Yes.

Could this problem be caused by RPM Averaging Lag Factor set to 10?

Totally unrelated.


James

[rabid]

It is a hall sensor so does it matter which edge I use?

For any input the Input Capture should normally be set to "Rising" as the input circuit is designed to work that way. This translates to a falling edge outside the box. For Hall inputs this 5V->0V edge is typically electrically "stiffer" so is the best to use, the less stiff edge will have more phase (timing) shift with RPM.

Interesting. So the setting in tunerstudio should be rising and the sensor and wheel should be setup that way. But then you say the 5V to 0 transition (falling) is the better edge? I am going to need to figure if my sensor pulls high or low when a tooth is near it. I am using ms3x cam in on the cpu. I am not using the expansion board with a zero crossing circuit.

My old wheel was set to falling edge 72 degrees which put it on the up stroke compression. It also had that same pattern of tooth but closer to the compression "peaks".

I would have expected that to work better as that is a more typical angle to use. Did it ? Why did you change the wheel ?

I was having this same problem before with it. I read in the manual that a 4 cylinder is best setup for a 90-120 degree setting. So I had new wheel lasercut which would mount so I could get it in that range. I thought the rpm would be more stable during cranking near the missing tooth but it doesn't seem to be the case. Also the old wheel had a chipped tooth.

2017-08-23_18.12.57.csv

Old wheel tooth log

(63.51 KiB) Downloaded 18 times

[jsmcortina]

Interesting. So the setting in tunerstudio should be rising and the sensor and wheel should be setup that way. But then you say the 5V to 0 transition (falling) is the better edge? I am going to need to figure if my sensor pulls high or low when a tooth is near it. I am using ms3x cam in on the cpu. I am not using the expansion board with a zero crossing circuit.

My comments were based on using the on-board circuits which invert the signal. i.e. falling edge outside the box is "Rising" at the processor.

James

[rabid]

I cut off tooth 1 and reset everything. I really think this will solve all issues. The missing tooth is obvious and the engine starts quickly, and on the same cycle every time. I can't get any sync loss at all. Time will tell.

The log shows three cranks and starts. You can see the difference in the missing tooth length from before.

2018-07-10_18.26.25.csv

36-2 cranking running logs

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2018-07-10_18.33.39.msq

(251.29 KiB) Downloaded 18 times