GEMS - General Engine Management Systems Ltd - Forum

I'm trying to use an EM36 on a Ford Zetec engine. The engine is fitted with the stock VR sensors for crank and cam. Crank is a 36-1 trigger, and the cam provides one pulse ever 720degrees.

Cranking with the plugs in I get I_Tooth and F_Tooth incrementing up to 12 and then go to zero at which point "Timing Error" increments. Engine speed to cycle quite a lot during cranking, between 150rpm and 220rpm. With the plugs out it seems to behave fine with F_Tooth counting to 23 and wrapping and I_Tooth counting to 11 and wrapping. I'm presuming the ECU is incorrectly detecting a missing tooth when the engine slows down during cranking - are there parameters to help control this?

Also I can't find any mention of using the cam to select phase in the EM36 manual? I was hoping I'd see Cam_Tooth_Count incrementing and Cam1_Angle reporting something but these are both at zero during cranking. The CAM sensor apears ok on a scope (+/-500mV VR waveform at cranking speeds) and it apears on ADR13 with peaks up to 3648.

regards
ian

Ian

Would seem that your basic set-up is correct. You could try double battery to starter only.
The parameter MX_Tooth_No is very useful this should match option MX_Sync_Test = 34, we use A_tooth = 0, as valid tooth so 35 actual teeth translates to to 34.
You may need to remove JP2 for maximum cam input sensitivity.
You should also check Crank_Falling_Edge and Crank_Rising_Edge, when correct parameters Miss_Time/MX_Tooth_Time = 2 +/-5% but this can only be none when running above 600rpm. In later versions of firmware there is Start_MX_Time which may be relaxed from normal running MX_Time, note 0% means use MX_Time setting for backwards compatibility.
So use internal data log of high speed; A_Tooth, MX_Tooth_Time, Miss_Time, T2_Period.
T2_Period will change at the detection point assuming T2 (Cam2) used for synchronisation. It is often better to separate crank and cam testing by disabling cam sync with no edge set and running semi-sequentially Ign_cycle_Teeth and Fuel_cycle_teeth = 12 and halve MicroSec/bit. Later versions have Start_No_Cam_Sync for just such a situation.
Indeed when running Cam_Tooth_Count will increment and be reset to zero at syncronisation, equally Sync_Error will count 0, 1 repeatedly.
As ever a data log will tell so much more.

Rich A

I solved the cranking speed last night so now its maintaining crankshaft sync when cranking. MX_Tooth_No is constantly reporting 34 and F_Tooth_No and I_Tooth_No are counting correctly. However, Miss_time is always reading between 54 and 52 yet MX_Tooth_time varies from 6646 to 21980?

As for the cam sensor, T2 Period is still always zero. I've removed JP2 but ADR13 appears to be exactly the same (peaking at 3584 during the cam pulse). Still no Cam_Tooth_Count or T2_Period.

Is there any way I can send you the logged data to have a look at?

Ian

There is a scaling issue with Miss_Time while cranking as the most significant byte of the 24bit measurement is lost.

You can send me the .stf log file zipped as an attachment.

Rich A

hi Rich,

Attached is the current cal and a log from cranking.

One thing I have noticed from the ADR13 channel is that the cam pulse appears at different points relative to A_Tooth so I'm not convinced the crank sync is working correctly.

cheers
ian