s300 issues USDM P30

[L337TurboZ]

My friend has a Del Sol that I am trying to help him with. He has 2 USDM P30 ECU's. Car has a B20 non vtec. The one that runs the car is socketed with a B20 non vtec map. The s300 ecu will run the car, but not smooth with the laptop disconnected. I can communicate with the s300, my software is up to date, works on other Honda vehicles and shows live data. This ECU is not showing live data at all.

I was able to pull a calibration off the ECU, it showed for a B16 vtec, had the previous owner (of the s300) information on it. Cleared it out and loaded a B20 base map. the car ran ok at idle, but when I disconnected the laptop (after exiting the software) it cut off. restarted the car without the laptop connected and the rpms were fluctuating. Reconnected the laptop and even before loading up the software the car had already smoothed out. It seems like with the laptop disconnected the car will not run properly.

Reconnected the socketed ECU and the car runs fine.

The connection option (lightning bolt) is grayed out, but it does show online/offline in the lower left of the screen. when connected via cable it shows online. I know that what changes I make to the map affect the vehicle. For example I changed ignition timing numbers in the idle region and the car responded to change. So the laptop is connecting to the ECU but the ECU doesn't seem to run off the calibration at all unless the laptop is connected to it. Below are pics of all the information I have for the vehicle. The Hondata is registered. Thank you for any help.

Software information




USB cable being used



ECU setup for Hondata


Sockted ECU the car is running on normally

[Hondata]

Reconnected the laptop and even before loading up the software the car had already smoothed out

If this happens then stop and check the engine grounds and main harness ground on the thermostat. If there is a bad ground in the vehicle it can ground through the USB - you don't want that.

[L337TurboZ]

He has a wire tuck and I checked all the grounds. All are there and seem to be good. I will have him check grounds again and add a secondary off the T stat straight to battery negative to see if that helps.

[Spunkster]

You should try the ECU in a known working vehicle. If it works there then you need to correct the wiring in the vehicle with issues before using it or you will damage it.

[Hondata]

Don't add extra unnecessary grounds. Check voltage and current flow between the battery negative and any other point of the vehicle with a ground - thermostat housing, ECU ground, valve cover etc until you find the problem.