Hey guys, got my Holley terminator efi it a week ago and am doing pretty good so far on the installation. I know there's a few guys here that have it, and I am curious about what you all did about your battery negative/chassis ground. Holleys instructions requires a 1 gauge wire directly from the battery negative to the engine block. And 4 awg from the engine to the frame. Now, all being Corvette owners here we know the battery is in the back of the car and bonded to the chassis. Did any of you guys run a dedicated battery negative cable to the engine block?

 

I think the more grounds, the better. A ground directly to the engine block just means the spark plugs have that much better a connection for their circuit. Also, steal (the frame) is not as good a conductor as copper cable.

 

There's a factory ground cable from the frame to the engine block.

Be sure to run the EFI power and ground directly from the battery. Do not cheat and take power from the horn relay or starter motor.

 

It's no fun, but I'd suggest to follow the instructions. I drilled a hole in the firewall next to the AC harness grommet to run the cables above the inner heater box, then under the center console -> park brake console -> enlarged the hole in the rear bulkhead just to get the power cables directly to the battery.


My ECU is mounted under the overflow tank on the passenger side fender. It was the most convenient spot I could find after installing the A/C delete cover.


Nick

 

thanks for the info dembo, i'm going to do about the same things you did, i pulled my ac coil out and i'll get the delete kit (my car had ac but doesn't now and probably never will again). My only concern is that Holley suggests if your going to put the ecu in the engine bay that you should mount it with the wire connections facing down so that water can't get up into the ecu. Problem is because of the curve of the fender you can't mount it very well like that. I might just mount it sideways like you did.

I have some copper braided battery cable that is long enough to go from the battery negative to the engine block, but its #4. Do you guys think i should still get #1 like holley wants, they claim if you don't follow their instructions to the letter it will void your warranty. #1 awg wire ain't cheap, and isn't easy to find by the foot either. I installed a brand new battery to frame and a brand new frame to engine cables, #4, i wire brushed the contact surfaces before installing. And also a brand spanking new battery with side and top posts.

Also, i was thinking about running my ecu power cables under the car, and zip tie it to the starter positive cable to follow it back to the battery. It would be the most direct route but i'm wondering if when the starter cranks if it'll induce noise on to the ecu power cables. I've taken my dash and console all apart before for other projects, i just really didn't want to take it all apart again if i can help it.

 

You're right about the orientation, but as you found out we don't have a lot of options in these cars. I'm pretty confident that no water will enter the connectors the way I mounted it. I had a coolant overflow (overfilled) but it just ran down the fender. I did mount rubber spacers underneath the ECU as the fender curve was to big, in order not to distord the ECU. Underneath the ECU there's a metal plate (between frame and fender) so there's no water splashing in from below either. (I've driven the car in the rain).
FWIW, I have the normal battery replacement cables to starter and frame from the known vendors.
Personally I would keep the harness away from anything that creates noise. Starter, blower motor, HEI, spark plug cables. Most of these systems are sensitive. I also first thought about running the cable along the battery cable but opted to run it inside to avoid possible noise issues.
I've got to admit that the harness does go around the blower motor, then along the firewall and inbetween the AC delete cover and block it drops down over the block to get it below the HEI.
No issues so far.

Nick

 

You're good. Just run the ECU power and ground directly to the battery. There's no need to add any dedicated battery<->engine ground.

I have the Holley HP (same ECU) on my '71 for several years done that way. Works fine.

I put my ECU behind the pass side dash pad.

 

Hey just an update, i got my terminator up and running last weekend. its a lot of money to spend, but dang does it work good. I ended up mounting the ecu on the fender under the radiator overflow and running the cam/battery cables through a new hole in the firewall. Turned it all on, did all the setups, took two cranks and fired right up and went into a perfect idle, didn't even spit or cough just ran like it was a brand new car. Couldn't believe it. I also did run the 4 awg wire from the battery neg. to the engine.

Looking through my spare parts there is a little plug with a resistor on it that looks like it would plug into the cam cable, whats that for? There's nothing in the instructions about it.

 

Congrats & great choice on cable routing & ECU location :-)
I think you are talking about the Canbus terminator?
From the instructions : 'There is a second connector marked “CAN 2”. This connector requires that a “CAN Terminator” be installed. This is included in the parts
kit. See Figures 13 & 14 below.'

 

Yeah that's what I'm talking about dembo. I've got an email to Holley about if that has to go in or not. I've got over 200 miles on the thing so far so I'm guessing its not a big deal.

 

just a quick wrap up, got several hundred miles on the car now. the holley terminator has yet to fail or fault, its like having a whole new car. i used to avoid having to start my corvette if i needed to just move it a little out of the way. it was always such a pain to choke and pump the car to start and then had to let it warm up before i could put it in gear or it would die. Now i just hop in, start it and go. Wish it hadn't cost so much but the only alternative are wait for the sniper system to maybe be available to buy or dumped a ton of money on an LS1.

 

Congratulations! What year, what engine and tranny, and any other mods to car? And when you get moment (You're probably enjoying your transformed car so muchthat you can't stop driving it...) how about posting some pictures!