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