VEC2 PWM Question

[Jim Wilson]

I'm running a VEC2 to control the additional injectors on my DLM S/C setup. When cranking the motor, the PWM gets power and thus the additional injectors fire. This floods the engine to the point were it will not start. As a fix I've installed a manual switch to disable the PWM during startup, then flip the switch back on while driving. Not exactly my idea of a perfect set-up, there has to be a better way.

Does anyone know if there is a better way around this? Maybe a relay or power delay of some sort? Perhaps there are software mods that will fix it?

Thanks!!!

 

[DAMN YANKEE]

Jim,

First let me say right off that I do no currently use the PWM (pulse width modulation) panel. I also do not run a DLM S/C. Your application is to provide additional fuel injection so the following applies:

The programmable output signal used to activate a switched component has the ability to be set-up to activate at full throttle and between certain RPM ranges. Your VEC software has loaded values in both the "PWM Load" and "PWM RPM" tables. One would need to see all those values to be helpful to you.

What does this all mean to you, hopefully everything. If not...in simple terms...nothing should be firing off your additional injectors until load parameters have been met. If I understand correctly, your injectors are firing at crank. Again, knowing your table values would help considerably.

Would you please tell me if the box in the "boost" panel is checked or unchecked?

Lastly, you own a VEC, call Sean.

 

[Joseph Dell]

I'm running a VEC2 to control the additional injectors on my DLM S/C setup. When cranking the motor, the PWM gets power and thus the additional injectors fire. This floods the engine to the point were it will not start. As a fix I've installed a manual switch to disable the PWM during startup, then flip the switch back on while driving. Not exactly my idea of a perfect set-up, there has to be a better way.

Does anyone know if there is a better way around this? Maybe a relay or power delay of some sort? Perhaps there are software mods that will fix it?

Thanks!!!

Jim -

This is the only issue that I know of w/ running the injectors off of the PWM with the VEC2. I used a momentary switch which, when pressed, broke the ground so that the injectors wouldn't fire. I talked to Sean about this at the time I installed the set-up and he said that this is what the VEC is suppose to do. But it probably does this with the W/M set-ups too... they just don't dump enough W/M into the motor for people to notice.

I'd recommend AVOIDING a permanent switch as you could accidentally leave the switch in the OFF position and the no more extra fuel.

Joseph

 

[Jim Wilson]

Hey Joseph, I guess I'll try the momentary switch. You told me about that quite a while ago, but I couldn't find one. Just ordered one from McMaster Carr though.

It would be great if no switch was needed at all, like some device that would delay power to the PWM circuit for say 5 to 10 seconds while cranking.

DY, Yes the PWM is set to fire at a certain RPM and Boost, but it also fires during cranking, which floods the motor.

 

[DAMN YANKEE]

Joe is the man on this stuff...

I was thinking maybe you checked the boost panel by accident, seems this "condition" is a known one.

I would think your crank delay cycle would be a good solution and one a programmer could hammer out. Ill pop this thread off to Sean.

 

[dansauto]

DY, Yes the PWM is set to fire at a certain RPM and Boost, but it also fires during cranking, which floods the motor.[/quote]


wow I did not know that!!

I am using it for w/m at 10#+ boost. I wondered why it sprayed once when starting the motor so I unhooked it for now. as I did not want to lock up the motor. So you are saying add a momentary switch in line? But I want to make sure it does spray as soon as I hit 10# boost, wont it dely there as well?

 

[plumcrazy]

that momentary switch only shuts it off (grounds) it during the moment you are holding the switch. once you let go, its back to being on again.

 

[davem]

Another option is to use a relay triggered by oil pressure to power the injectors. Relay open when pressure is below 10psi, closed above. Napa sells oil pressure switches.

-Dave.

 

[1TONY1]

Yes, this is a post from the dead Just searching for an answer to another question. Another option would be to change over to a SRT10 start button like some have done....you get the "cool" factor of a push button start (WOW) and the same button could operate a relay to "undo" the PWM connection. Clutch switch could also be used but would disable injectors every time the clutch pedal was pressed/depresssssed ??

 

[EllowViper]

I know when I was using a variable (progressive) boost card with the PWM, my W/M LED would flash during cranking. Now I understand why. When I use the PWM output as a simple boost/RPM referenced on/off switch, it does not activate when cranking.