Author Topic: 74 Challenger EFI and.... Oh yeah Twins  (Read 11133 times)

Offline quagmire

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Re: 74 Challenger EFI and.... Oh yeah Twins
« Reply #75 on: March 02, 2016 - 07:59:02 pm »
Yup....  They are not polarity sensitive.  Whatever you do with ANY Megasquirt controlled actuator that has 12v going to it, make sure the 12v comes from the same source that supplies the Megasquirt (same relay or fuse).  Otherwise, you could have issues with backfeeding voltage when you cycle the key OFF.




Offline YellowThumper

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Re: 74 Challenger EFI and.... Oh yeah Twins
« Reply #76 on: March 02, 2016 - 11:27:02 pm »
Quagmire, thank you for the look and suggestions.
It will be a couple of days before I can get at it again.

One question is this statment.

"The brown signal grounds should be tied into the sensor ground coming out of the MS3."

Is the sensor wire the (brown also) Wire coming out of th e MS3? Pin number 36?

I will change settings and test with light as you have offered.

As for the power. No the coils were not powered up when initially booted. I do however have a couple of additional ones I could swap in to try if all else has failed.
I am using the battery for power. Have charged it regularly to be sure. Disconnected of course...
All the power is coming directly from a trunk mounted jy sourced fuse and relay block. It is being fed with an 80 amp continuous duty relay with an equivalent breaker. Relay is triggered by a relay that is on for start and run but does not power up for accessories.
Separate fuses for all items such as MS, coils, injectors and fuel pump. But all are basically fed from the same buss bar.

Good suggestion on the headlight idea. Will use it.

Also a tip non MS related. Years ago I had a problem with the battery going dead on my Mustang. Small low end draw would kill it. (Old timer) said to disconnect positive side cable and wire a light bulb in between. Yup sure enough it lit up. Leave on and then start disconnecting wires, plugs, bulbs, etc... until it goes off. Now you have at least narrowed down source of short. Simple but effective.

Thanks again guys.
Looking towards positive updates coming soon.  ;)

Mike
« Last Edit: March 02, 2016 - 11:37:53 pm by YellowThumper »
Removing the warning labels one at a time.
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Offline quagmire

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Re: 74 Challenger EFI and.... Oh yeah Twins
« Reply #77 on: March 03, 2016 - 08:28:57 pm »
No.  Pin 7 is your sensor ground and is on the main DB37, not the MSX DB37.  The brown wires from the coils and the grounds for TPS, IAT, ECT, and any other sensors requiring a ground all need to tie into that circuit.  What pin out diagram did you reference when wiring everything up?


Offline YellowThumper

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Re: 74 Challenger EFI and.... Oh yeah Twins
« Reply #78 on: March 03, 2016 - 10:17:45 pm »
Ahhhh Ha that "sensor ground" you speak of...
All my (most still unused) sensors are tied into the #7 you stated.
Using the online version of Megasquirt-3 V3.0/V3.57 wiring.
I will rewire it for that then. Mentally I did not put 2 and 2 together for them and the other sensors.

Man I wish I was home to try this.
Currently out scouting other HS girls playoff game. Teams we will be playing soon. Daughters team is currently ranked 15th in country. There are 37,000 schools nationwide. Brea Ladycats!
Sorry proud dad moment again.

Thank you again!
Mike
Removing the warning labels one at a time.
Nature will take care of the rest.

Offline GreenFish

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Re: 74 Challenger EFI and.... Oh yeah Twins
« Reply #79 on: March 04, 2016 - 09:04:08 am »
I've had a LOT of those A ha! moments with this project.  :roflsmiley:
70 cuda, 440, KB pistons, 10.5:1 compression, edlebrock heads,RacerBrown cam, 5-Speed Tremec, Megasquirt EFI

Offline YellowThumper

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Re: 74 Challenger EFI and.... Oh yeah Twins
« Reply #80 on: March 17, 2016 - 10:35:38 pm »
So with the EFI struggling issue I needed to take a breather. Took out my cam sensor and dropped the dizzy back in, bolted and wired up the stock coil and got her running again. Ahhhhhh. Only a temporary side track. Will be back at it again soon. I will say again a big thank you to the several guys out there helping me...
So to have some tangible forward movement I relocated my rear bumper inward 1-3/4 and up slightly. Still may move it in a little more.  Here are the steps. Not 100% finalized but will explain with the pics.

To start I have never had the bumpers off. Have had car since 83. But looks like someone bolted this one without the washer on the backside and the nut was buried in the body hole. Time for the Sawzall :2thumbs:.


Decided to make my own instead of trying to cut and reweld factory piece. What I did was use it as the fixture jig for my pieces together. 1/4 thick by 2 inch stock.
Cut and slotted my pieces to match.


Made a couple of 1-1/2 inch thick blocks. Drilled a 1/2 inch alignment hole. The block and bracket thicknesses add up to the 1-3/4 movement. Aligned it with some bits and clamped it in place.


And welded away


Of course when you don't have any local car friends you have to get creative.


Wholly cr.. it is unbelievable how much better it looks. Had I known this it would have been done 30 years ago. OK possibly no. I did not have the skill back then...



The mounts currently use both body bolts but I only have the inboard one attached to the bumper. Reason is with only one attachment point I have a huge pivot point to get the bumper exactly where I want it. To get it closer to the body I still have the ability to slightly bend/flatten out the Z shape of it. When all is mounted in its final happy position I will remove from car but leave the bracket attached to the bumper. This (because I still have the heavy crash bar) will become my other "fixture" for welding the second half mounting plate in. It sits at an odd angle. This way there is no guessing for proper position.

Now for the tail pan openings. For now I will just make some sheet metal filler plates that will bolt in from the back side. Nothing complex. Temporary because I will be modifying another by welding openings up and making custom exhaust openings in it. But like everything else it will be a long project.

Mike
Removing the warning labels one at a time.
Nature will take care of the rest.

Offline dakota

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Re: 74 Challenger EFI and.... Oh yeah Twins
« Reply #81 on: March 18, 2016 - 05:42:46 am »
Really nice work on the bumper Mike.

Offline YellowThumper

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Re: 74 Challenger EFI and.... Oh yeah Twins
« Reply #82 on: March 18, 2016 - 01:27:39 pm »
Really nice work on the bumper Mike.

Thanks.
And Doh. Looking at my post I realize an error in my thinking. The setup only moved the bumper in the 1.5 inches as apposed to the 1-3/4 I was shooting for. Gonna have to fix that... Theory was that if it was moved too far in I would only have to shim it out. If the move was not enough. Fine tuning becomes more difficult.

Mike.
« Last Edit: March 18, 2016 - 01:44:46 pm by YellowThumper »
Removing the warning labels one at a time.
Nature will take care of the rest.