Trigger errors

[SierraCos2wd]

i have some trouble with my trigger signal.
When i drive below 3000rpm on no boost, i see in megatune that i lost my rpm signal. Starts jumping from etc 2-3000rpm to 0rpm an the car starts to jump forward etc.. But when i push the throttle an the car starts to boost then the rpm signal its ok. Its only happend when i drive easily around 3000rpm an below.

I have 18-1 missing tooth wheel with hall sensor 1GT101 an no cam sync. Use distrubtor an msd6AL ignition box with msd blaster 2 coil. Could this cause the problem?

I use firmware 1.0.73final Vems V3.3 Engine is a 2.0l Cosworth
1 x Assembled v3.3 controller
  - secondary_trigger: HALL
  - primary_trigger: HALL
  - mounting-style: screws
  - LCD connection: yes
  - ignition driver: 8
  - MAP connection: 400kPa (6/4mm pneumatic)
  - PS2 connection: no
  - Knock and EGT: yes
  - Flyback: 30V flyback
  - 1-wire interface: no

Here are my msq file:
http://www.vems.hu/files/TomAndreSetnan/gevingaasenmap.msq

Hope someone could help. 
Maybe this should be in another thread

Regards
tom andre
norway

[rob@vems.co.uk]

Can you scope the signal coming from your 18-1 trigger?

Hall is pretty good when it comes to handling noise, so I have to wonder if there's a problem with the ECU loosing sync with the trigger - at low speed it may be seeing a missing tooth where there is none.

[SierraCos2wd]

yes i can try to do that today. Can it be something else?

[jadzwin]

I have noticed that the pullup voltage measured at EC36 pin 27 for primary hall sensor is 2.8V (I've measured this voltage in 3 vems, 2 genboards ver3.5 and 1 genboard ver 3.6)
For ATMega128 input high voltage is 0.6*Vcc so the minimum voltage should be 3V. We had very similar behaviour in one of the car (VW Golf 60-2 Hall), and additional 10K pullup resistor helps. For secondary input (hall sensor) there is regular 5V and everything works very well.

Kuba

[z0tya]

Special n-1 in primary trigger should be enabled?

[d00ze]

Check your grounding to the coils. I hade the same problem with trigger errors on my ca18det. My problem was bad grounding to the coil bridge.
Installed a new ground wire to the chasie and the problem got soloved.