EFI with Promag 44, crank trigger

What crank trigger sensor are you running? Right now I am running a basic MSD crank trigger sensor but think I might be picking up some noise.

 

we use the basic msd flying magnet on our promag 44 BS3 turbo hemi without problems

 

With this sensor, do you have anything shielding the wires?

 

Do you have a cam synch?

 

I dont have a cam sync yet, Moran said it was not needed at this point. Here is what its doing...

Problem is staging. 2 step is set to 3850 testing. RPMs come up on the transbrake, the computer shows it will start dropping cylinders at 3440 RPMs, around 3650 its worse, it will finally get on the chip but not as fast it could be if it didn't cut cylinders at 3440. Once its on the limiter hard it will keep the motor 3850-3820. Any ideas?

 

pickup shielding

the wires on the MSD triggers are twisted together to cancel or reduce the impact that radiation from plug wires has on it. The wires should be as isolated from the plug wires as possible (we run ours along the bottom chassis rail)

 

Have you scoped the trigger signal?

 

I have not scoped the crank signal while the car is running, I have a feeling its a dirty signal. Just a few months ago when I had an MSD8plus, the 2/3 step worked flawlessly. Now since adding the promag44, its starting to drop cylinders about 400 rpms before it gets to the 2 step RPM. I wonder if one of the "Premium" crank sensors from FIE would be any better.

http://fuelinjectionent.com/webstore/product_info.php?products_id=207

The coil and points to mag wires run somewhat close to the crank trigger wires. Maybe 2-3" away.

 

I dont know how to take a decent screen shot of a BS3 replay but here goes...
2 step is set to 3850
starts dropping cylinders at 3352

[/IMG]

 

pickup concerns

I would put money on it (your money of course...) not being the trigger, if your wires are only 3" away you need to seperate them. Also they should never run parallel with each other, right angles are better. Also if you are going to use a scope you will have to isolate it via an isolating transformer otherwise you will effectively earth one of the terminals when you connect the earth probe of the scope. You will also need to know what you are looking for and how to drive the scope properly.

 

The wires pass at a 90 degree angle
They are probably 2 1/4" apart where they pass
.100 in gap on the crank trigger
The only thing changed was the ignition from a MSD 8 to a promag 44 and now this problem comes up

Whats your money on being the problem?

 

intereference

Hi again, I dont know much about the promag 44's as I have always run an MSD 10+ but I do understand interference. Another thing to check is that your heads are bonded together with a high grade earth wire and then to the chassis as well. This needs to be as large as practicable and contain as many strands as possible. I thought the correct gap was .060 for the mag pickup, maybe someone could confirm as .100 seems large...

 

interference

I assume you are running the MSD spiral plug leads as recommended by MSD and not any non spiral versions.

 

id reduce that .1 to .070 / 080 for a startdid moran do your map??
did you run the msd 8 on this exact same set up?

 

Never been a big fan of MSD's pickups, as the one in the pic is not shielded or grounded
Give Dave Leahy a call
http://www.electrimotion.com/

 

Firecore 50s

 

I ran the MSD8Plus on this exact same setup. I can try a smaller gap and see what that does but it was .100 on the MSD8plus and worked like a champ.

 

Yes, I've got great grounds on the heads and chassis.

 

Just went through this. Use double shielded wire for anything going to or from the ProMag components. Solder everything. Ground all components (Mag, coil, points box, ignition controller, block & heads, etc.) together. Crank trigger brand doesn't matter for this. 44 is a different deal than a MSD 10+, have run both. Call me if you like.