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Trying to finish up my EFI harness and I was wondering where some of you all have attached your grounds. I have 66 coupe with 5.0 EFI. I am also planning a trunk mounted battery. I was planning on running the battery ground from the batt. to the rear frame rail. I know I will need a ground from the motor to the chassis, I need some ideas here for a clean, solid place to ground. I also have the EEC grounds, TFI shield ground, etc...
I'm sure I am overthinking this but, if someone has a successful scheme I would love the input.
Thanks,
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When runnning grounds for EFI, you can not over do it..
You can ground the battery to the unibody if you weld in a proper terminal. That will give you what you need for starting the car, but you also need to ground the EEC (or aftermarket processor) directly to the battery, so run a dedicated decently sized ground from the battery post to the EFI.
John
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John, Thanks for the reply.
Here is what I think I have left:
1 EEC pins 40 and 60, I will run these directly to the battery?
2 Fuel Injection Harness Power circuit (per the FFI website) relay grounds to the battery?
3 HEGO power grounds, to the chassis?
4 HEGO Ground (ring lugs) my harness has one at each O2 sensor. OK?
5 MAF sensor ground, to EEC 40 and 60 wires or to battery?
6 EEC pin 20 "CASE GROUND" to chassis?
7 TFI shield to CASE GROUND at the chassis?
8 Battery to chassis, weld on solid connection point.
9 Motor to chassis, where is the best place to do this?
10 Secondary ground from intake to chassis or firewall, is this necessary?
11 I haven't installed the remote starter solenoid yet. It has 3 lugs, Battery +, Out to starter, Solenoid power. I assume that the solenoid gets ground from the mounting bracket. I will run a ground from one of the bolts to the chassis?
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Here's what I've done with a couple of harnesses and had no problems so far. Hegos, 60/40, ignition shield, about all of the EFI grounds, all come together and ground to a 3/8 stud at the back of the right cyl head. Also from that stud I have a fairly heavy ground strap attached to the firewall. All relay grounds are put down to the left fender apron where my home-brew PDB is mounted. I think I pick up some other ground there also. The battery neg cable goes directly to the engine block and attaches with a 3/8 bolt. I also have a 12Ga hot and ground running to the FP at the fuel tank. The FP ground comes forward and I think it goes down with the other grounds near the PDB.
All ground surfaces were cleaned of any paint/corosion before making them up. Then I touched up the engine bay paint as needed with RO 7777.
I've never had a problem or any indication of high resistance or poor grounding either with the enginge mgt system or any lighting. Main thing I've found over the years is that you bond every part of the car together: Body, frame, engine/trans, battery, and in some cases, the running light socket bases. And always ground the neg cable to the engine block/trans for minimun resistance. Rear battery applications need to take care with this and do it right...ask Corky how we know about that.
Ford distributes the grounds all over the car but I don't know if that has to do with convienence or some other reason but I'm betting convienence ($$$$). As long as everythig has a solid, clean path to the neg batt post you'll be okay.
BB
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I agree with BB 100 %. Make sure your grounds are to bare clean metal and things will work fine.
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Thanks, and you peaked my interest, what happened to Corky with his battery relocate?
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KStang wrote:
Thanks, and you peaked my interest, what happened to Corky with his battery relocate?
Just run a heavy ground cable all the way forward to the engine or trans. DO NOT rely on a Neg cable connection at the rear frame rail or body.
BB
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Bullet Bob wrote:
KStang wrote:
Thanks, and you peaked my interest, what happened to Corky with his battery relocate?
Just run a heavy ground cable all the way forward to the engine or trans. DO NOT rely on a Neg cable connection at the rear frame rail or body.
BB
Yup!
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I have a trunk battery with EFI -
Negative cable straight to the rear frame rail
Welded subframes
Large cable from engine block to front frame rail
Cable from block to firewall
Never had any issues
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JamesW wrote:
I have a trunk battery with EFI -
Negative cable straight to the rear frame rail
Welded subframes
Large cable from engine block to front frame rail
Cable from block to firewall
Never had any issues
Agree: the unibody can carry as much current as any cable you can fit in the car IMO. But I would still suggest a decent sized (14 ga) ground wire from the battery back to the processor.
John
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Standard tool used on every ground attachment. A must for all toolboxes.
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