ISIS wiring questions

[jay cozz]

I have started to layout my wiring and have a few questions.

1. where are the best spots to mount the rear powercell, front powercell, mastercell, and bulkhead connection?
2. there is a connection directly from the ISIS system to the KOSO dash for ignition and signal lights, how do I get the rest of the inputs to go from the ISIS into the dash?
3. where is the best spot for speed sensor system? Do I disregard the speed sensor that is on the GM wiring harness?
4. there is two fuel pumps and one connection from the GM harness, do I use this connection at all or do i wire both to the ignition?

 

[J. Salmon]

I can only answer 4.

I am assuming you have 2 fuel pumps because you have a primary that feeds a swirl pot and a second pump that feeds the rails? In which case they both come on together? Some ECUs have a fuel pump control wire. If so, connect this directly to the mastercell input wire that controls the power circuit that you have the pump on (or if they are on separate power circuits, connect it to both input wires). Then the ECU goes to ignition. When you power up the ECU, it will turn on the pump.
Otherwise you can put the fuel pump mastercell input lines straight to ignition, or to a switch on the dash that is separate. If you use a switch on the dash, you will probably want it to be dependent on the ignition on also, so no ignition no fuel pump.

I found I had to make a big chart showing the logic of how I wanted every switch in order to figure how to wire the controls. For example, do you want to be able to have the lights on with the ignition off? How about radiator fans?

Anyway, I hope this helps.

 

[Alex]

I have my front power cell and master cell on the driver side; I made an aluminum "kick panel" to protect them. Rear power cell went in the back, driver corner beside the gas tank

 

[Will Campbell]

I have started to layout my wiring and have a few questions.

1. where are the best spots to mount the rear powercell, front powercell, mastercell, and bulkhead connection?
2. there is a connection directly from the ISIS system to the KOSO dash for ignition and signal lights, how do I get the rest of the inputs to go from the ISIS into the dash?
3. where is the best spot for speed sensor system? Do I disregard the speed sensor that is on the GM wiring harness?
4. there is two fuel pumps and one connection from the GM harness, do I use this connection at all or do i wire both to the ignition?

You'll have to determine where you want the cells. If you are using the new kit from RCR, the manual should show where the harness assumes the cells will be located.

The RCR-specific ISIS harness that has the CAN bus connectors also has wires to the Koso gauge and back to the rear powercell, but the actual connections and use of the wires is up to the user. The manual will eventually be updated to show a suggested connection scheme for the new gauge.

The speed sensor can be placed anywhere, but the front wheels are the easiest, as they are closer to the gauge and so the wire won't have to be extended (or extended as far). Several options are possible, but the likely one is to mount the Koso speed sensor on the upright such that the sensor counts the back of the wheel studs. That's how I have mine done.

Re the fuel pumps, I suggest that the LP pump be on a separate circuit so it can be started a second later (or earlier) than the HP pump. Staggering the start times slightly makes it less of an instant drain on the powercell (or the system in general, if you are using an old-fashioned fusebox). ISIS makes things like this very easy to do. You may also want the pumps to start on a slow ramp-up, instead of hitting them all at once with max current. This is also easy to do with ISIS. Actually controlling the pumps should be done by signaling the ISIS system via the GM ECU, IMO, instead of letting the GM ECU just turn on everything at once. If you do use the GM ECU to turn on multiple pumps, please examine the fuse on the factory fuse panel for the pump, and be sure that it is adequate for allowing all pumps to start simultaneously, allowing for an inrush spike at start, when all DC motors draw more than their rated current for a brief time.

 

[Bill Musarra]

I'm going to have to get the instruction book for the ISIS system. It intrigues me with the things I have heard about it. I am thinking of rewiring my 40 in a year or two.
I do have a question myself about it and this thread brought it up. With the fuel pumps, how would one handle safety ideas like shutting the pumps off in case of an accident/roll over, low oil pressure situation. I have these taken care of with my conventional wiring. Also how would one hook up a run on after shutdown for a set of fans. I use engine bay fans to cool the compartment after shut down on a circuit timer set for 3 minutes.
Anyone???

Bill

 

[Alex]

I'm going to have to get the instruction book for the ISIS system. It intrigues me with the things I have heard about it. I am thinking of rewiring my 40 in a year or two.
I do have a question myself about it and this thread brought it up. With the fuel pumps, how would one handle safety ideas like shutting the pumps off in case of an accident/roll over, low oil pressure situation. I have these taken care of with my conventional wiring. Also how would one hook up a run on after shutdown for a set of fans. I use engine bay fans to cool the compartment after shut down on a circuit timer set for 3 minutes.
Anyone???

Bill

Fans - you can describe the shut-down condition you want to isis (e.g., run for 3 minutes after you turn ignition off), they'll re-program the master & power cells to support it, and you flash the master and power cells with their re-programmer (that they will loan you)

fuel pump - you would use a low oil pressure switch and a roll-over switch and wire it inline.

e.g., 1 wire from master cell goes to one end of roll-over switch, other end of roll-over switch to ground. 1 wire from power cell to fuel pump, then ground fuel pump. then when you roll over the roll over switch triggers and breaks the ground which stops the power to the fuel pump.

that's the real simple way to do it.

 

[Will Campbell]

Fans - you can describe the shut-down condition you want to isis (e.g., run for 3 minutes after you turn ignition off), they'll re-program the master & power cells to support it, and you flash the master and power cells with their re-programmer (that they will loan you)

fuel pump - you would use a low oil pressure switch and a roll-over switch and wire it inline.

e.g., 1 wire from master cell goes to one end of roll-over switch, other end of roll-over switch to ground. 1 wire from power cell to fuel pump, then ground fuel pump. then when you roll over the roll over switch triggers and breaks the ground which stops the power to the fuel pump.

that's the real simple way to do it.

Alex is correct. Another way to do this is to use a single inertia switch as is common practice in Ford cars. I have one from Pegasys that is wired into one of the inputs on the Mastercell. The logic on the ISIS has the switch wired in an AND logic to the ignition, so the pumps can only be powered if the inertia switch isn't tripped. This kind of switch covers the roll-over and severe impact scenarios.

 

[Paul Osborn]

I'm sure I'm not the only one to appreciate the irony of Alex steadfastly refusing the "unnecessary complexity" of EFI whilst simultaneously relishing the "flexibility" of ISIS.

Sadly, I find myself agreeing with him, i.e. why EFI when a carb will work, and ISIS is significantly superior.

 

[Bill Musarra]

Paul and Alex,
I would agree with both of you except there is an alternative. Its called the best of both worlds. "If" you opt for the size/shape and ease of adapting a carb for filtration purposes, because we know that filtering an EFI on these cars is not easy and sometimes not pretty, Then there is a compromise in the offing. There are self learning systems out there that take the hassel out of tuning a system. Some of the providers are names like Holey, Megasquirt, and others. With Holley for instance you can have the 4 barrel TBI with the Avenger Dominator series. You can even use the 4 barrel air cleaner. There is internal data logging if you wish. They have harnesses even for the LSX engines. On the Holley TV web site you can watch the self tune in progress. It is all done with a fob no larger than your fob that unlocks your car.They have a lot more on the TV site from wiring to fuel line and other products.
Holley TV : Featured Holley TV // on the PowerTV Network
MegaSquirt has a self learn setup that allows you to do sequential FI and ignition with individual cylinder trim for both. Logging of almost any or all parameters. Their info can be found at:
DIYAutoTune.com Megasquirt Kits / Assembled Engine Management Systems, Wideband o2 Sensor Systems and tuning products
You owe it to yourself to check out this information. You get the modern advantages of EFI with the look of old school carb. My engine builder likes these systems but says they don't work their best with a cam with a lot of overlap. Some features can't be read(sensed) very well.

Bill





holly hollytv.com watch self tune dominator efi
megasquirt iii ems datalog without laptop

 

[Alex]

I'm sure I'm not the only one to appreciate the irony of Alex steadfastly refusing the "unnecessary complexity" of EFI whilst simultaneously relishing the "flexibility" of ISIS.

Sadly, I find myself agreeing with him, i.e. why EFI when a carb will work, and ISIS is significantly superior.

Alexisisisisisis, making perfect sense since 1982 :drunk:

Paul and Alex,
I would agree with both of you except there is an alternative. Its called the best of both worlds. "If" you opt for the size/shape and ease of adapting a carb for filtration purposes, because we know that filtering an EFI on these cars is not easy and sometimes not pretty, Then there is a compromise in the offing. There are self learning systems out there that take the hassel out of tuning a system. Some of the providers are names like Holey, Megasquirt, and others. With Holley for instance you can have the 4 barrel TBI with the Avenger Dominator series. You can even use the 4 barrel air cleaner. There is internal data logging if you wish. They have harnesses even for the LSX engines. On the Holley TV web site you can watch the self tune in progress. It is all done with a fob no larger than your fob that unlocks your car.They have a lot more on the TV site from wiring to fuel line and other products.
Holley TV : Featured Holley TV // on the PowerTV Network
MegaSquirt has a self learn setup that allows you to do sequential FI and ignition with individual cylinder trim for both. Logging of almost any or all parameters. Their info can be found at:
DIYAutoTune.com Megasquirt Kits / Assembled Engine Management Systems, Wideband o2 Sensor Systems and tuning products
You owe it to yourself to check out this information. You get the modern advantages of EFI with the look of old school carb. My engine builder likes these systems but says they don't work their best with a cam with a lot of overlap. Some features can't be read(sensed) very well.

Bill





holly hollytv.com watch self tune dominator efi
megasquirt iii ems datalog without laptop

No system is completely self-learning - they can populate the base tables fairly well, but Holley et. al will all tell you the same thing - you'll want to go on the dyno with it eventually to get it fully tuned.

 

[Bill Musarra]

This is true. One could leave it in the learn mode for a period of time and get 98% of what you would see. A good dyno run will fulfill two goals. One, it will help the final tune. Second I think almost everyone on the forum would want a run to see what their engine will do. This would be a twofer in that you are charged for the run(usually by the hour) and the tune, which has to be done on almost every engine that is dynoed. I doubt there is a perfect first run.

Bill