Wiring help!!!

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Cazbah362

Cazbah362

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OK - I have read through all the threads and I am a bit perplexed. I am wiring a o2 sensor which needs switched 12v source that's hot in accessory, crank and run positions of the key.

Well I wired this to the side of the ballast that has power when then key is turned on, however I have learned this is not hot not hot on all three occasions. With that said, can someone tell me the best source to meet all three of these. I was looking at the fuse block, but not sure which area.

this is on a 70 Challenger (yea, I know not an abody, one project at a time.) Since I am slow, any graphics would be greatly appreciated.

Thanks in advance
 
I have an O2 sensor on most of my classic cars, either for a rich/lean indicator box or a Holley Projection fuel controller. All are wired to "ignition power", which is what you did. I don't think you have access to "Accessory" power in the engine bay, only in the cabin. I have no idea why you would need to power it from that. Don't believe everything you read in instruction manuals.
 
I'm with Bill I don't know why you need power in accessory. There IS NO accessory power available under the hood. Only switched power in the engine bay is "ignition run" which is what you have.

Make sure you are on the correct side fo the ballast.
 
I'm in agreement, not necessary in accessory position. On my truck it is wired through a relay connected to the fuel pump, ignition and injector power relay (ASD relay). Of course you want the O2 sensor's heaters to come up to temperature as soon as you can to get accurate readings. If you have an electric fuel pump I think I'd connect to that. Good luck..
 
All - Yes, I am doing a DIY with a Megasquirt II via their relay board. I have it wired in the fashion as shown in "Nova" which you posted (the simple wiring). The issue is the the o2 sensor does not come up in the TS software, however it does come in the gauge and the LM programmer, neither of which need this type of power. With that said I am working through the power issue, since power drops on start sequence which they say you need ((normal for all mopars) switched 12v source that's hot in accessory, crank and run positions of the key) when wired the way I have it.

So with that said does the Accessory plug in on the fuseblock have power in all three sequences? (switched 12v source that's hot in accessory, crank and run positions of the key)

Reading seems there is one either Ign1 or Ign2 that has power in all three phases, however not sure where to find this - Like I said, do well with pictures.

Thanks and I really appreciate the help
 
RedTruck - I think that is the next path, I am just trying to confirm the three phases (switched 12v source that's hot in accessory, crank and run positions of the key) is/are available on this one - Thanks
 
Cazbah362 said:
All - Yes, I am doing a DIY with a Megasquirt II via there fuse block. I have it wired in the fashion as shown in "Nova" which you posted (the simple wiring). The issue is the the o2 sensor does not come up in the TS software, however it does come in the gauge and the LM programmer, neither of which need this type of power. With that said I am working through the power issue, since power drops on start sequence which they say you need ((normal for all mopars) switched 12v source that's hot in accessory, crank and run positions of the key) when wired the way I have it.

So with that said does the Accessory plug in on the fuseblock have power in all three sequences? (switched 12v source that's hot in accessory, crank and run positions of the key)

Reading seems there is one either Ign1 or Ign2 that has power in all three phases, however not sure where to find this - Like I said, do well with pictures.

Thanks and I really appreciate the help
Click to expand...

You kind of lost me. I'm now assuming? that you want accessory power so that you can manipulate programming with the ignition system off/ engine off?

If so, I would suggest just either an underhood connector or switch to disable the ignition/ regulator at those times that you want the sensor/ computor "hot."


Here's how Mopar ignition switches work, which in reality are several switches in one can. NONE of these circuits are fused

1---Accessory. This switch is hot in both run and accessory, and feeds directly to the switched buss in the fuse panel.

2--Ignition run, or "ign 1" Traditionally dark blue, this feeds power to the gauges/ cluster, and goes through the bulkhead to feed the ignition/ alternator field/ regulator. It is hot ONLY in run.

3--"Start." Traditionally yellow, this goes through the bulkhead to the start relay, and nowhere else, unless it goes through the reset relay for the seat belt interlock on some model years.

4--"Bypass" or "IGN 2" Traditionally brown, this only goes one place -- from the switch, through the bulkhead, and to the coil + side of the ballast resistor. Ignition "run" goes cold during start, so this wire supplies ignition voltage in start. It's purpose is to bypass the coil resistor for a good hot spark during start.
 
67, no sorry not trying to confuse, power is applied right now with key turned to accessory the way I have it wired now, assumption is when cranking or when engine is started power is removed for a brief time, I believe this point is causing the ecu to clear or start over causing my issue.

The directions DIY provide, they are pretty explicit in this area stating you must have power in all three phses. Your explanation of the different switching functions help, thanks. I hope explained this better.
 
No, and for good reason in factory cars. You really don't want such things as the radio/ stereo or other modern electronics powered while the starter is switching/ running.

I still do not understand why you need power in accessory.

You could power the item a couple of ways in both start and in run

1---If you convert to an ignition system which does not need a ballast, you can tie IGN1 (run) and IGN2 (bypass) together

2--If 1 above will not work, you could power the component(s) in question with a relay. This is assuming you have an ignition which must have a ballast. What you would do is to use two diodes. Connect one diode to one end of the ballast (the run end) and the second diode to the other end of the ballast (the coil +) end. Spice the remaining end of the two diodes together and use that point to power the coil of a relay, with the other end of the relay coil grounded.

Diodes have a band at one end, and you must hook the band end towards the relay. What this network will do is to power up the relay in run and start both.

If you use a "Bosch style" relay as in the drawing, hook

85 to ground

86 to the junction of the two diodes

30 is one contact. Hook to an inline fuse holder coming from the starter relay battery stud

87 is the second contact. Hook it to the items you want to power

RelayWiringGuide.jpg
 

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I think even with a relay there would be a split second when the current switches from one source to another. A different ignition system that doesn't require a lowered coil voltage in run would be the optimal solution.
 
Redfish - I believe you are ultimately correct, I was trying to avoid that. I may be speaking with Trailbeast seeing if his product can work on this issue or simply go with the bolt under HEI
 
Great web site. I filed it away for when I play with EFI more. The wording mentions only "run" and "crank" positions. Only the figures add the "ACC" key position to the mix. I don't think you need the ECU powered in accessory position.

I am with 67Dart273. Which terminals (ACC, IGN1, IGN2) get power in each position is a function of your "key switch" and isn't found in the wiring diagrams. I had assumed that IGN1 got power in both "run" and "crank" positions, but found it doesn't (engine wouldn't fire while cranking). The switch powers IGN1 & ACC in "run" and IGN2 alone in "crank". If you go HEI, lose the ballast, and connect IGN1 & IGN2 together you get 12 V ignition on 1 wire in both "run" & "crank", which is what you need. If you keep the ballast, I think you must move IGN2 (brown wire) to the upstream side (with IGN1). That is what I did for now in my 65 Dart since using a Crane XR700 that needs a ballast. I just removed the factory ballast, jumpered IGN1 & IGN2 at the firewall and put a ballast right at the coil. I don't get full 12 V while cranking, but it fires up fine.

On another topic, the website jumps thru some hoops to install the EFI fuel pump near the tank (as most people do). In my cars, I put it on the lower frame of the engine bay, where it is easy to get to. It works fine and I think that is a lower position anyway, unless climbing a very steep hill. I understand the Walbro pumps I use can suck to 5 ft elevation anyway.
 
Bill - Thanks on the tip with the pump, I am doing this in phases, so have not gotten there yet on the pump. I am doing a 3/8th line with 1/4 return, looking at a dual pressure regulator. Need to boil out the tank first, don't trust the 40 year old steel
 
By the way I'm sure we would love to see some photos of your project


This last summer I have been running a Holley Commander 950 (TBI), electric pump of course, GM HEI module (the old style) and of course need no ballast

On my 67, I just tied IGN1 and IGN2 together from the IGN switch which fires a couple of relays. One relay powers the pump, another powers ignition and EFI. There is no trouble with mine in regards to a switching glitch between start and run. On my system, there are times when I want to fire up the EFI with the engine off to load and download the programming info. I just put an insulated disconnect in the relay coil wires which fire the ignition and pump. This allows the EFI to power up so the laptop can talk to it.

In my opinion, you may be overthinking this based on what may be poorly worded website destructions. After all, many others are running these systems on Mopar and other vehicles, and I know of no problems

The Commander project

http://www.forabodiesonly.com/mopar/showthread.php?t=209528&highlight=commander

Other unfinished experiments with EFI

http://www.forabodiesonly.com/mopar/showthread.php?t=205959&highlight=holley%2C&page=2

http://www.forabodiesonly.com/mopar/showthread.php?t=209237&highlight=commander
 
Cazbah362 said:
Bill - Thanks on the tip with the pump, I am doing this in phases, so have not gotten there yet on the pump. I am doing a 3/8th line with 1/4 return, looking at a dual pressure regulator. Need to boil out the tank first, don't trust the 40 year old steel
Click to expand...
I ran a 3/8" supply tube in my Dart and use the factory 5/16" tube for return. However, 5/16" is fine since Magnum engines used that. Put a carb-type fuel filter before the EFI pump and a fine filter after. I used the Corvette filter/regulator that many rodders use (Wix, $20 O'Reilly's). It returns at 56 psi. All TBI's I know of have a built-in regulator, as do most early MPFI rails. Around 2000, most switched to a "return-less" system with the reg in the tank to meet new EPA rules. That might be the only case you need a separate reg, in which case the Corvette one is a great deal. Every time you change the filter, you get a new pressure regulator.
 
Bill - Thanks for the information, i will keep it in mind.

67 - I will post pictures a bit later, really all it is a bunch of wires and silver boxes, and its an E-body, don't want to offend on the A forum.
 
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