M4 has a miss when disconnected from laptop

[AzzzzzA]

Hi All,
I have a 2000 F150 with a Vortec blower and M4. The tuner has got the tune completed but if he closes the Motec program or disconnects the (prehistoric) laptop the car starts missing about every 10 seconds and sometimes even cuts out. This has him stumped. Has anyone got any ideas please?

[Stephen Dean]

Hi,

This sounds like a grounding issue, with the ECU grounding through the laptop connection, rather than the vehicle grounds.

[AzzzzzA]

Hi,

This sounds like a grounding issue, with the ECU grounding through the laptop connection, rather than the vehicle grounds.

Thanks mate. I'll get him to check this out.

[AzzzzzA]

Hi,

This sounds like a grounding issue, with the ECU grounding through the laptop connection, rather than the vehicle grounds.

Thanks mate. I'll get him to check this out.

[AzzzzzA]

Hi,

This sounds like a grounding issue, with the ECU grounding through the laptop connection, rather than the vehicle grounds.

Thanks mate. I'll get him to check this out.

Thanks again Stephen. It now idles ok. He tells me they redid the earth. But the saga continues and I'm wondering if it could be related. It has a random 'hiccup' when cruising with the throttle just barely open i.e 60km/h 1300-1700rpm-ish. He doesn't seem to be able to tune it out. Do you think this may be related?