70 Challenger RT - EFI 6 Pack Conversion

[70chall440]

So, I played with the column, no change. I reviewed the wiring and cannot see anything that would cause this. I traced the wires that used to go my coil; one (grey went to the neg side for the tach); red to the pos side the went to the side of the ballast resistor that has the brown wire and a black with yellow tracer for the electronic ignition box. None of this is currently connected; so I am wondering if I was supposed to connect something there? if I hook the red wire up to the positive side of the coil, the car will not start no matter what (although I did not try that hard as I was concerned about burning something up).

The search goes on..

[70chall440]

Alright, I have studied this until my eyes are bleeding and I am still not sure what is going on, that said I was sent a link to another thread on this forum discussing connecting a MSD ignition. Currently, my MSD "switched 12V" is connected to a distribution block under the dash that has switched 12V to it (used for stereos and such); however after reading the thread I believe the correct wiring should be as shown here. What still continues to baffle me is how the engine will start with a remote starter button but not the key.

As always, comments are welcome.

[70chall440]

I have been thinking about it and think I "might" have the answer to my problem, what I am thinking is that when I crank the car with the switch, the "switched" power that I have connected is not getting power, however when I hit the remote switch it is. Therefore I need to correct the wiring... I have arrived at this modified version of the diagram above which does not show the red wire that ran from the ballast resistor to the coil, however I can mock the diagram I am showing here easily enough to prove or disprove my theory.

[70chall440]

For those interested, here is an update. I have fixed my key starting issue, turns out both the MSD and ECU needed to be connected to the blue and brown wires as where I originally had them wired did not get power while cranking.

I purchased a MSD tach adapter but haven't installed it yet. To be honest I am not real confident it will work; I called MSD and they said to connect the grey wire which I did without effect. Rich told me to hack into the Holley harness and tap into A28 which I am not super excited about either as those wires are pretty thin and reading the instructions and documentation; it appears that the ECU produces the same signal as the MSD 6AL (a square wave) so I think it would (or wouldn't) work the same as the MSD grey wire. The adapter is a bit confusing as it basically taps into the white trigger wire. I will most likely mock it up and see what happens.

F&B sent me a new IAC as the one I had seemed to be having issues; installed it and all seemed ok until the car warmed up although it seemed to be struggling some. After the car warmed up the IAC set at 0% and that's about where we are.

I will not be able to work on it for a few weeks as I am off tomorrow early to tech some long range shooting and then next Saturday going to Vegas for SEMA. I do have Thursday and Friday but we will see what happens.

[70chall440]

Update - I returned from my last trip late Tuesday and had some things to attend to yesterday, but today I thought I would take another stab at trying to get this car to idle and get the settings where they need to be. After some work on the timing it seemed to run ok but would stumble about every 30 seconds to 1 minute, usually the IAC would catch it but a few times it would die. I reviewed the software and discovered a few settings incorrect which I fixed; tried it again and it was better. Still a slight stumble in there but much better.

I think I am at the point where I need to redo all of the wiring and make it permanent, then drive the car and let the software learn. Unfortunately, this will have to wait as tomorrow I need to get ready to drive to Vegas for SEMA.

[70chall440]

I am trying to get my factory tach to work before I fix the wiring completely. I am running a Holley ECU and Dual Sync distributor which triggers off the white wire. I have tried to connect the grey MSD wire to the tach, didn't work and I recently bought a MSD adapter 8910 because it says it is for a system where the white trigger wire is used whereas 8920 is for use with a magnetic pickup. Rich is telling me to tap into a harness wire A28 as that will supply a tach signal but I believe it will produce the same signal as the MSD 6AL (which doesn't work). So, I am going to try the adapter but I thought I would put it on here in case anyone has any definitive information.  I did call MSD and email them; when I called the "guy" said to use the grey wire, which as stated didn't work. I received an email from them saying to use adapter 8920, but it clearly says it is for a magnetic triggered system which my system is not. Nothing can be easy..

[70chall440]

The tach adapter didn't work, so I am not sure what to do now.

[usraptr]

The tach adapter didn't work, so I am not sure what to do now.

I'm having the same issue with my factory rallye tach.  Additionally, my engine wouldn't start with the tach wire hooked up to the neg side of the coil.   I checked the continuity of the wires yesterday and all is good so the tach wire isn't grounded somewhere, so I'm also at a loss.  I'll be following your progress to see if you solve the mystery.

[70chall440]

I am going to SEMA and am going to talk to MSD. I am considering replacing the tach with a rebuilt one designed to take the MSD signal (tachman)

[GoodysGotaCuda]

I am going to SEMA and am going to talk to MSD. I am considering replacing the tach with a rebuilt one designed to take the MSD signal (tachman)

Where are you staying? We leave Tuesday for the show, staying at the Luxor


Sent from my iPhone using Tapatalk

[70chall440]

Where are you staying? We leave Tuesday for the show, staying at the Luxor


Sent from my iPhone using Tapatalk

Circus circus; not my first choice but just need the room 

[marc70challenger]

Good stuff in thread!  Have fun at SEMA! 

[70chall440]

Good stuff in thread!  Have fun at SEMA!

I will certainly try 

[marc70challenger]

I will certainly try 

   /salute

[70chall440]

Got back from SEMA, awesome time. if I can manage to get the pics off my phone I will start a thread about it.

Update (Tach) - talked to MSD at length (Crash340 can attest to this as we visited them like 9 times); the guy there after some lengthy discussion stated I needed tach adapter 8920 which I promptly ordered. I installed it today as per the instructions and BAM... it works!!!! Disregard the "Magnetic Pickup" language, install the wires as shown and your factory Mopar tach will work..