Cranking Continuous SyncErr

[duncanw]

Hi,

I have a Motec M84 currently wired up to a 4.0L V8 in a Landrover Discovery which throws SyncErr's during cranking and the engine will not fire. The SyncErr is thrown during constant cranking, if I clear the errors during cranking then it will reappear almost immediately.

The engine is only receiving spark during the first one or two turns of the starter motor when I crank the engine. That is to say, every time I attempt to start the engine the initial cranking only produces a spark during the first second of a 5 second crank. I know this because my timing light only shows flashes during initial cranking when I am attempting to check the engine timing.

My question is going to be in two parts :

First will a SyncErr prevent an ECU to tell the ignition coils from sending a spark ?
Second, can someone please double check my crip calculations

The Engine

The crankshaft uses a magnetic sensor, has 60 teeth at 6 degrees intervals and are 3 degrees wide with a -2 reference @ 60 degrees BTDC.

Camshaft uses a hall sensor and sends 4 pulses every 2 crank revolutions.

I set the crip value based off of this Ref/Sync Capture.

Method 1
- I know that the missing teeth are at 60 degrees BTDC, therefore TDC is 10 teeth later.
- The camshaft tooth is aligned with the sensor at tooth 16 on the crankshaft. So once the ECU is armed at this
point it is looking for the next ref signal, which makes tooth 17 my index tooth.
- So, (60 - 17) + 60 (another revolution) + 10 to get back to TDC = 113 teeth from the index tooth.
- 113 x 6 = 678.

Method 2
- TDC is at tooth 10.
- The index tooth is 7 teeth later.
- So, 7x6 = 42
- 720 - 42 = 678

Therefore I have assumed my CRIP value is 678.

ECU Setup

In the Ref Sync Setup I have the Ref / Sync mode set to 8: Two missing teeth once / cycle. At this setting the SyncPos % in the sensors screen maintains a steady 50%. If I change the Ref / Sync mode to 9 : Two missing 4 times / cycle. Then the SyncPos % wanders from 20% to 80% during cranking.

Both produce a SyncErr, so I'm not sure what is going on here. If someone could please verify my calculations and most importantly my assumptions then that would be a big help.

EDIT : Sorry, also forgot to mention that although I am getting a sync err, the Synced status is reporting OK during cranking.



direct link

Thanks

Duncan

[yotamhks]

something isn't setup/wired correctly. ecu sends a default spark once the switch is turned, that is the spark you see.
other then that ecu doesn't understand engine turning. do you have a constat rpm reading? what kind of ignition are you running?
post your tune file, that might help more.

[duncanw]

Thanks for the reply,

Ok that explains the initial spark that I'm seeing.

The ignition system is the standard landrover system (ERR6045). I'm not sure who makes it, it's either Bosch or the prince of darkness (lucas). But it's a wasted spark ignition system. I've tested the operation via the Tools -> Test Outputs utility and all seems well during testing.

My crank rpm is constant, but it seems very low to me as the ECU is saying it's turning over at 200rpm. But it sounds faster than that to the ear. My attempts to change the REF mag levels have no impact on the reported RPM by the ECU.

I attempted to upload the tune file as an attachment, but it gave me an error that m84-10 files are not allowed. If you know of an alternative way to get the file up then let me know and I will do that.

Thanks

Duncan

[SprinterTRD]

Change the number of cylinders to 48 this will force the ECU into group fired mode and ignore the cam sensor. Check and adjust the crip value to get the timing right. see if the engine starts.

If it starts then the ECU may not recognise the CAM trigger pattern correctly.

[duncanw]

The maximum number of cylinders for the M84 is 8. But I will investigate how to get it to fire in group mode to rule out the CAM trigger pattern.

Thanks

Duncan

[SprinterTRD]

-8 in CYLS will do the same then choose ref/sync mode 8, 2 missing once per cycle.

[duncanw]

Thanks for your help so far, I did as you suggested and the SyncErr was cleared when the cylinders was set to -8.

But apart from the initial spark when I crank the engine, no spark is happening. So it looks like I have a problem with the ignition system. I will do some more research into the ignition coils this engine uses and then try again.

Thanks

Duncan

[duncanw]

Quick update, I suspected that I was getting no spark because of bad spark plugs, I've replaced them with new ones and I now have a good spark when the cylinders is set to -8. The engine didn't fire but it felt like it was close.

When I put it back to 8 I have no spark, so it looks like it's got something to do with the cam sensor.

[J&R]

The ref sync mode you are trying to use is incorect for this engine configuration

MODE 8 : TWO MISSING TEETH ONCE PER CYCLE

Requires the REF Signal only, does not require the SYNC signal as the
cycle synchronisation information is provided by the missing teeth.

REF SIGNAL :

The REF Signal must have 2 adjacent missing teeth once per engine
cycle.

On 4 stroke engines it must be derived from the Cam/Distributor.
On 2 stroke engines it can be derived from the crank.

This is straight out of the help file for the m84 mode 8 help file

If it is easy enough remove the other three teeth from the camshaft and run mode 7
If not
then contact MoTeC melbourne and get one of the tech support guys to help.

The closest mode I can see directly for this is mode 17 BMW oem 60-2 and 4 uneven spaced on cam but with out a closer look at the Ref/Sync capture I can not tell wether it would work or not.
cheers
Iain

[duncanw]

Thanks Iain,

I only just realised that the help menu on the sync mode is a dropdown box... I kept on going to general help which isn't very helpful.

But I think I will contact Motec for their help as I was hoping that this would be an easy fix. Mode 17 doesn't work either, I tried that and it still gave me a sync error.

Thanks for everyone's help.