Johnny*G

Hello, long time listener, first time caller..LOL. I have a '87 Trans am 5 speed with a L98 out of a 1990 t/a. So i installed a Motorsport supercharger for a 5 psi gain of fun. Then I installed an FMU...even more fun. This weekend i wired in a used Vortech(MSD) Boost Timing MAster. I connected the wires according to the diagram. I turned the key on and the fuel injectors started clicking. The engine is not running. What could cause the fuel injectors to get a pulse signal withour the engine running. I turned over the engine and it started right up and ran normal. When cranking the injectors do stop clicking, back in on position they click again. Any thoughts my friends?

Johnny*G

Ok so after coming home and playing around more. Here is what I found: I turn the key on, the fuel injectors pulse, there is a spark signal from the coil, the fuel relays kick on, the air pump solenoids kick on. Its like this thing wants to come to life. I'm confused. Its hard to believe that even if the MSD was faulty it would backfeed the ECM....

RBob

iTrader: (1)

For the injectors to fire the ECM needs to be receiving distributor reference pulses (DRPs). The distributor will only send a DRP when it is turning. So something in that set up is causing the ECM to see DRPs.

Does the BTM box tie into the RefLo or RefHi signals that go to the ECM?

RBob.

Johnny*G

Johnny*G

RBob, Thank you for your reply!! I posted the wiring diagram to show the way I wired it. Now the diagram does not show the other 4 wires coming out of the distributor....but this BTM does not tie into it at all. I did disconnect the red lead and played with it with the key on. It turns on all the sensors and actually pulses the injectors, so weird... but if I undo the wire all goes back to normal. AND if i remove the BTM completely it works normal. I can't see how this unit being defective could do this. Is it RFI? do i need that MSD capacitor? p/n 8830...I really do appreciate the help!

RBob

iTrader: (1)

That capacitor may help, even though it is more for radio noise from the MSD unit.

The above diagram makes sense. One thing is that the BTM ground lug should go to the engine block for ground. Not the firewall or such.

For the wiring, the heavy pink is the ignition switched +12 volts to the coil. The coil ties that to the other connector as the red wire. This provides +12 volts to the ICM. It is tapped into to power the BTM on it's pink wire.

The white wire that gets cut with both ends going to the BTM is the coil trigger. In stock form the ICM grounds the white wire to dwell (charge) the coil, then releases it from ground to fire the coil.

Now the BTM is doing that.

As you mention, it doesn't tap into the ICM's 4 wire connector which goes to the ECM. So the injectors shouldn't be pulsing.

Disconnecting the BTM's pink from the ICM red wire powers off the BTM. It seems to me that the BTM is creating some sort of interference into the ICM which is causing it to send a DRP to the ECM.

Without getting a scope hooked up I can't say why. If you have access to the capacitor, try it, can't hurt anything. Odds are the BTM is spiking the red power lead that also goes to the ICM.

RBob.

junkcltr

iTrader: (1)

Sounds like you didn't cut the white wire coming out of the dizzy.

The white wire is 0 to 5v with 5v being charge coil. Orange is 0 to 12v with 0v being charge coil. Wiring them together will cause an endless coil fire loop due to the inverse nature. This firing is what is causing the ECM to fire injectors as a by product.

You mentioned with the BTM disconnected it works right. Well, it shouldn't if the white wire is cut like it should be. It shouldn't run at all.

Check that you cut the stock white wire, connected the BTM white wire to the dizzy white wire, and connected the BTM orange to the coil white wire.

Johnny*G

Hello, So i had some more time to dive into this. Found that the wiring is just like it should be. I undid the connection at the orange to white wire, then attached a test light between the wires. With the resistance, the problem went away and the car started like normal. ???? Now i'm confused. I can't see how the box could be the issue but i'm leaning on that. Or do I install a resistor? maybe that would screw with the timing function and negate everything i'm working towards?

Johnny*G

Hey all, I didn't want to leave everyone hanging. I found out the box was faulty. had a friend bring over a similar unit and it did not do this. Weird though. It set codes in the ecu also. PROM and MAF codes. Again thankyou for all the insight. The reason I didn't condemn the box right away is because i saw it run on another car. Oh well.