Omex 600 YB Cosworth

Hi Guys and Gals,

Helping a friend of mine trace an intermittent misfire on a YB that's controlled by an Omex 600 ECU. Coils and plugs have been changed out already, no effect.

I have connected to the ECU over serial using their MAP4000 software and all looks to be working OK, confirmed the AFR with an external Wideband and it looks OK, albeit a tad rich. The only thing that's jumping out at me is a counter on the first screen titled "Timing Errors". All I can find online is that this should be 1 as the ECU sees the -1 tooth (he late YB had a 36-1 pickup and runs EEC IV) and inturn knows where TDC is- there is no sync signal on the 600 series Omex so it's running batch fire.

I have disassembled the main ECU plug and found signs of old water ingress and some very mild oxidisation of the pins, which I've cleaned up. No sign of water inside the ECU on the main board and 99.9% of the time it runs faultlessly.

The concern over this Timing Error parameter is that I've noticed it get up to a count of 12 over a short journey but I wasn't watching at the time to confirm correlation between the increase in value and the misfire event. Does anyone know what this number indicates???

this number normally relates to trigger errors and often fixed by renewing the crank sensor adjusting the gap and or adjusting the trigger thresholds if it uses a reluctor type sensor

but you are on the right track checking to see if the errors are going up when the miss fire occurs it can be normal to see a trigger error on start up but normally only 1-2 and should not do it again once going.

you could also use a scope to check the crank pattern this should show whats going on and help you trace it. keep a open mind as it could be a number of things still

Hi Ross,

Thank you for the reply. Funny enough I had a response from Omex directly to the same effect. They have also suggested increases to the MX_Time of 15 retesting each time.

Will report back but it's good to know for sure what this number is indicating!