Detect Protocol Ecotec miata

[miataman94]

Hey all,

I am stumped beyond belief right now. I have a 2.4 ecotec swaped miata with a swap specialties wiring harness. Ever since my first time attempting to scan my ECU with my MPVI2 I have gotten a detec protocol error. I have contacted support and they confirmed that everything is supported but there is still sone outstanding issue. My MPVI2 worked on my truck so we can cancel out the usb and Mpvi2 its self. I have power and ground and what seems to be small values of power for data at the correct pins on the OBD2 port. So PLEASE HELP! I don't know what else to check. Any ideas are greatly appreciated. Also we can rule out the ecu as I have tried 3.



Luke

[tunerpro]

It sounds like either the CAN bus isn't terminated correctly or the high / low signals are backwards. It must be terminated at both ends of the bus (the ECM has terminators in it, so this counts as one terminator).

[cobaltssoverbooster]

Adding to tunerpro, for you or other users, termination resistors are by standard 120 ohms. Everyone calls this resistor a terminating resistor but its job is to prevent differential feedback between the high and low signal lines. A 1/4 Watt rating should be fine for CAN since its transmission current is low. I use Vishay Dale or TE Connectivity resistors on my Mega Squirt CAN bus.
I use these for board mounted solutions - https://www.mouser.com/ProductDetail...mdDYrEKZ2hM%3D
and these for termination of harnesses - https://www.mouser.com/ProductDetail...eQstjOSQ%3D%3D
Reputable sources would be Digi-Key, Mouser, Newark, or Arrow Electronics. I source and order stuff for EE guys all the time for work and use these vendors with almost non-existent issues.

Use shielded wire for your can system as well. Like Belden 8641 (24 AWG) or 8451 (22 AWG). For each run of can wire, the shield should be connected to a clean ecu ground source on one end and unterminated on the other to prevent ground looping. Notice in the attached image that the shield only goes to ground on one side.

[EFIHARNESS]

give me a call during the week and we will get this sorted out. Steve 909 910 3867

[miataman]

i first read this was like i dont remember posting this. lol