The 10 pin engine harness and the EFI harness are separate. The Holley EFI harness only needs to be triggered by the ignition and is completely standalone. You can seperate all your MEFI stuff out of the engine harness and leave everything else like gauge sensors, starter wiring, alternator, etc.

In the case of factory gauges goes, Would I have to splice my factory gauge wires (oil and temp) into the Holley sensor wires to make my gauges work? Im seriously considering this route. Ive been mulling over the idea for a while to buy software to modify my tune or have complete control like this one. Thanks again for the great thread.

You can run a seperate temp sensor for the Holley.

Yes, the ecm needs to see coolant temp and comes with a sensor, there's always another spot to install it so you can keep your analog gauge. If you're switching from MEFI you can use the same coolant sensor that it was using. If you want the ecm to monitor oil pressure, fuel pressure, oil temp, etc. you can buy transducers and thermistors and plug them into connections already in the harness, then you can set up safety's or alarms for low pressure, or high temp situations.

Very nice. Thanks for the info. This sounds like a great product. Now getting an O2 bung welded into my existing lightning headers.

Haxby ...how do address a motor that you run cool water temps ........ ie no thermostat ..... my blower motors barely will run over 100*...which may not be the right thing to do .....Always thought if your oil temps are in the right range ~212* you should be good ..... will the holley setup monitor intake air temps? .....Talking to MB at Precsion he stresses intake air temp alot .... I forget the numbers but if you monitor air temps and get to a limit you really need to back off .......m

The cold water temp is no issue you just have to adjust the temp cutoff for fuel enrichment, basically like adjusting the choke on a carburetor, to make sure you're not adding any additional fuel when you reach your operating temp. All the Holley systems use and come with a Manifold air temp sensor. You can reduce timing and add fuel based on air temp by using a simple graph in the software. You can view air temp on a digital gauge if you like, or the touch screen. You could also set it up to trigger an alarm if it gets too high.

What about a MIL lamp or trouble codes?

Does anyone know if any of the electronics packages are NMEA 2000 data compliant?

UD

To answer a couple questions from the thread:

-What to do about the coolant temp sensor.

On my motors, we are running MEFI 5. I have one set of traditional Gaffrig senders feeding my analog gauges, and a complete set of Delphi senders going to the ECM. When running no thermostat, plug up the oil temp sender to the coolant sensor input, so the ECM tables key off of that.

-NMEA2000 compliance.

None of the engine controllers seem to be directly NMEA2000 compliant yet, including Caterpillar, etc. The MEFI5 and others output SAE J1939. I am doing this project right now, and I bought two Maretron SAEJ1939 gateways ($300 something each), one for each engine. I have to take one of the gateways down to the marine electronics shop to have them change the bit identifer code on one box from 1 to 0 for the port engine. Then, both gateways get plugged into the NMEA2000 backbone via drop cables. The NMEA2000 network then recognizes them as two different engines.

There are a couple different ways to set up the network, mostly depending upon whether you intend to run the J1939 network as stand-alones, or if they are networked. An example might be on a big yacht, you might want to have an actual J1939 driven display in the engineroom that can access all the engines/generators. In that case, your engine dealer would actually have to change the bit code in the engine ECMS. Either way, it still seems to require one gateway per engine. I'm not clear on exactly why one J1939 gateway cannot feed the NMEA2000 bus for both or all engines in this case, but I'm sure the designers know the answer to that.

If you are setting up a NMEA2000 network, remember to read the instructions carefully, and use the proper cabling and termination resistors. You cant exactly just connect a cable directly from one device to another.