Comms disconnect during dyno pull. CDI related?

[MattK@dentsport]

Hi all-

This is a V44 in a Nissan 240 w/ KA24 turbo. No matter what I try, the ECU will kick offline as soon as the engine comes up on boost. The ECU will disconnect from the laptop and not reconnect until the USB cable is removed and reinserted and the USB drivers reload. Same symptom on multiple laptops. We are using an MSD DIS-4 Plus to fire 2 wire Denso coils from a Honda CBR motorcycle. We have used a similar ignition system on other cars with no issues. Spark plugs are Denso IK22, no misfiring at all, just ECU disconnect.

I have already tried basic things like shielding the comms cable (also a choke), separating physically the ECU and CDI, and examining for loose grounds or bad connections. ECU firmware is the latest as well as VTP software. Any and all help would be appreciated. Thanks!

[Dave Kriedeman]

Are your sparkplugs Resisitor Type.

If not, fit resistor sparkplugs, tune the engine and then refit the non resistored sparkplugs.

[MattK@dentsport]

Based on my info from Denso and on a search at Sparkplugs.com the Denso IK22 is a resistor sparkplug.

[Simon]

Given it is load related it is likely noise is getting on to the USB coms.

I would suggest resistive plugs but the IK22's are so no change needed there.

Make sure the block is grounded really well to the chassis.

And if all that fails then you can try a serial tuning cable but you will need a serial port on the laptop.