Crank and Cam Trigger Sync on LS7

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SteveA
Posts: 5
Joined: Tue Nov 17, 2020 11:58 am

Crank and Cam Trigger Sync on LS7

Post by SteveA »

I have a newly installed Syvecs S7, which was supplied to me with a base calibration for my GM LS7 engine. The initial attempts at cranking won’t start and the triggers are not in sync. I get:

SYNC: 0->TURN
SYNC: TURN->360
SYNC: 360->0(LONG TOOTH GAP)

I went through the Syvecs help video for Crank and Cam Setup, to check settings and couldn’t see anything obviously wrong. I have not experimented with changing many settings yet as I am inexperienced, and this was supplied as a calibration that was supposed to work for my engine.

However, if there is anything wrong with the configuration, then I am hoping somebody experienced here can spot it right away. Below are the configuration settings in the ECU and attached is a validation log file from cranking events.

Any help/guidance about what to check next would be greatly appreciated!

Crank Sensor
Pin: AN01
Type: 5V Bipolar
Input Filter: Off
High Trigger Threshold: 100-500rpm/0.75V, 1000rpm/1V, 2000-10000rpm/2V
Low Trigger Threshold: 0V
Signal Trigger Edge: Falling
Reference Angle Adder: 0

Cam Sensor
Pin: AN02
Type: Thermistor
Input Filter: Off
High Trigger Threshold: 3.75V
Low Trigger Threshold: 1.25V
Signal Trigger Edge: Rising

Generic Crank and Cam Setup
Number of Crank Teeth: 58
Number of Crank Tooth Gaps: 58
Crank Reference Tooth Angle: 289°
Crank Tooth Gap Widths: 0/6°, 1/18°, 2-57/6°
Crank Tooth Gap Min: 0/3°, 1/9°, 2-57/3°
Crank tooth Gap Max: 0/9°, 1/26°, 2-57/9°
Crank tooth Gap Repeats: 0

Engine Configuration
Crank and Cam Type: Generic Single Gap Single Cam
Gap Ratio A/B: 1.5
Gap Validation: Disabled
Gap Validation ratio: 1.5
Omit Gap Detection Validation Revolution: Yes
Cam A Angle: 0°
Attachments
Crank221120.txt
(228.78 KiB) Downloaded 280 times
stevieturbo
Posts: 1321
Joined: Sun Dec 07, 2008 2:04 pm

Re: Crank and Cam Trigger Sync on LS7

Post by stevieturbo »

I don't see why your crank low trigger threshold is at zero, as a hall sensor will never cross the zero line ?

Change those thresholds to say 1.25v for both cranking and running

And also ensure manual cam checklist is enabled and setup for the cam trigger.
1.57 LS7 DBW.SC
S6Plus LS7 base cal. Compare settings to this.
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SteveA
Posts: 5
Joined: Tue Nov 17, 2020 11:58 am

Re: Crank and Cam Trigger Sync on LS7

Post by SteveA »

Thanks for posting. Will check.
Ryan.g
Syvecs Staff - Caretaker
Posts: 498
Joined: Fri May 30, 2008 4:05 pm

Re: Crank and Cam Trigger Sync on LS7

Post by Ryan.g »

This cal must of been converted from a S6 i would say and gone to the Default Values.

Set the Low at 1v and High at 3v across all RPM points and should be fine then
SteveA
Posts: 5
Joined: Tue Nov 17, 2020 11:58 am

Re: Crank and Cam Trigger Sync on LS7

Post by SteveA »

Thanks for the reply Ryan, sorry I didn't see it earlier. I ended up sending the car to a tuner who has it sorted now.
SteveA
Posts: 5
Joined: Tue Nov 17, 2020 11:58 am

Re: Crank and Cam Trigger Sync on LS7

Post by SteveA »

A follow up on this.

I enlisted some professional tuning help and we got the car running a while back. Its taken a few months to complete all the rewiring, Motec PDM and Plex dash installation done, then getting the can messaging sorted out so all components talk to each other etc.

In the process of final tune, we have now run into an issue with the crank trigger, where once it gets past 4000rpm the ECU looses sync on the trigger and drops the RPM to 0.The camshaft trace is perfect, but the crank output is erratic and gets worse with rpm.

Image

It looks normal on cranking:

Image

Once we get past 4000rpm the ECU will lose sync on the trigger and drop the RPM to 0, this is even with arming voltages set as low as 0.5 and 2.5 volts. The sync error log can be seen below:

Image

This has led us down the path of doing the following:

- Testing all earthing and sensor grounds to ensure good connectivity, moved Earth from Gearbox to Engine block
- Run new shielded trigger wiring to the Crankshaft sensor only and provide it with its own separate signal ground at the ECU.
- Tried a new crankshaft sensor which results in exactly the same output.
- Moved the sensor ground directly to battery ground to eliminate any interference, sensor output did not change, swapped back to the correct sensor ground pin
- Added additional earthing to the coil packs to allow for dissipation of any additional interference on the crankshaft sensor itself, no improvement found
- Swapped the Power to the crankshaft sensor from the 5v supplied to a 12v output from the PDM, no change in sensor output
- Swapped crank and cam pins and reassigned outputs, no change in sensor output, changed back
- Attempt to change input from 5v bipolar to thermistor, no output at all from sensor, changed back

With no solution we finally piggybacked in a Motec ECU to the same wiring loom, and no more issue. The trigger signal with the Motec is perfect up to 6700rpm.

Image

My tuner is out of ideas. Are we looking at a problem with the Syvecs ECU itself?
stevieturbo
Posts: 1321
Joined: Sun Dec 07, 2008 2:04 pm

Re: Crank and Cam Trigger Sync on LS7

Post by stevieturbo »

Can't see detail properly on the phone....

But what input is the crank sensor wired to ? How is that input configured ?
And what trigger edge are you using ?

LS crank/cam should be powered off 12v.

And what happens if you swap crank and cam about ?

If you scope the crank independently how does it look ?
stevieturbo
Posts: 1321
Joined: Sun Dec 07, 2008 2:04 pm

Re: Crank and Cam Trigger Sync on LS7

Post by stevieturbo »

Do you have the actual sync files ?

Even the rising edge on the cam looks soft. On mine with a 1x cam on the front of the engine, sensor fed off a generic 12v they're good and sharp edges on both sides, and a full 5v square. Which makes even the Motec trace seem odd, as it's only seeing 4v ?

Or was the last file an actual error at 4000rpm ? Which might explain the poor edges which is more a lack of resolution with the scope than anything ?

Can you hook up an oscilloscope to both ?

You're using the correct crank sensor ? I believe it's the grey for the 58x wheel.
SteveA
Posts: 5
Joined: Tue Nov 17, 2020 11:58 am

Re: Crank and Cam Trigger Sync on LS7

Post by SteveA »

The crank sensor is currently wired to the AN01 Bi-polar input. The cam is wired to AN02. swapping them made no difference.

We have now had an email reply from Ryan at Syvecs. His assessment is that sensor is overwhelming the weaker pull-up of the bi-polar input at high rpm, and that the quickest solution is move the crank sensor to a Unipolar input. The unipolar inputs currently are used for the four wheel speed sensors, so I am waiting for my tuner to implement a solution and let me know if the issue is resolved.
Trickster
Posts: 70
Joined: Mon Nov 28, 2016 6:09 pm

Re: Crank and Cam Trigger Sync on LS7

Post by Trickster »

Put the wheel sensor into the old crank sensor location

Graeme
MR2 Turbo 5sgte 750hp 527ft/lb Syvecs S6
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