rusefi.com

Hello, new here and from Sweden. I’m trying to install a Uaefi in my Volvo 740. The car was originally a 740 GLT with a 16V engine, but I bought it without an engine, gearbox, or rear axle. I took all those parts from a 940 Turbo instead. I completely rebuilt the B230 engine — it’s bored 0.060" over, and I replaced the connecting rods with H-beam ones. The cylinder head was swapped to a “531 head,” which I ported and replaced all the worn parts in. For the camshaft, I’m using a VX3 from a B230FB engine, and the turbo is a new TD04 19T.

With Rusefi, I’m trying to keep it as plug-and-play as possible with such an old ECU setup like LH2.4. In the PnP harness, I’m using the functions for controlling the ignition box, all relays such as the fuel relay, etc. I’ve also wired in the engine temperature sensor and the VR signal from my 60-2 flywheel. However, that stopped working — I’m getting a lot of missing teeth, so I’ll try running separate wires to it, like I already did with the MAP sensor, IAT, and TPS.

I’m afraid I may have damaged the board when I cleaned off the flux residue I missed after soldering the Molex connectors on the board using isopropanol. After that, I started getting interference on the VR signal, and I also get the message “C9012: out-of-order coil of coil 1” in the Rusefi console. I even get that error when I run a spark test in the console with only the Uaefi board connected to the computer.

I would assume that you have not broken anything. Some of our warnings are known to be false unfortunatelly.

The car runs without missing any teeth when i use the standard Ecu runs fine. but i am going to try new wiring to the Vr sensor now. i am most affraid of the error C9012: out-of-order coil of coil 1 did not have that code before i clean the ecu and i get it without hook up to anything

Are vr wires twisted? Shielded?

I redid all my wiring and went through everything, and I think I found a big mistake
I had connected the activation for my main relay and fuel pump relay to B9 Main Relay Weak Low Side Output 1 and B16 Low Side Output 4 / Fuel Pump Relay, but when I looked at the car’s original wiring diagram, those are supposed to be grounded, not receive a control voltage.
Yet the relays still clicked on, so I’ve probably managed to damage something.

"Low Side Output" is a grounding circuit; it either grounds the output or it doesn't. Your rusEFI Low Side Outputs should go to one activation pin of the relay (pin 85 on the relay) and keyed power to the other (pin 86 of the relay). It sounds like you probably did it right.

mpgmike wrote: ↑

Sat Oct 11, 2025 1:15 pm

"Low Side Output" is a grounding circuit; it either grounds the output or it doesn't. Your rusEFI Low Side Outputs should go to one activation pin of the relay (pin 85 on the relay) and keyed power to the other (pin 86 of the relay). It sounds like you probably did it right.

okey then i did right then i don´t know what i did wrong
https://ibb.co/q3fXzvF6
i use pin 20 and 21 in the ecu harnes for activate the relay

https://ibb.co/JjWXfxt9 that is my logg with just the usb connected it looks wierd right?

Grief! Talk about batch fire injectors! The ECU fires all 4 at the same time. Not sure what I'm supposed to see on your log. There are several trigger events, no coil events, and 4 "MAP/NO" events. I'm not sure how this relates to your questions.