Turbo wastegate solenoid freuquency

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04-11-2008, 10:04
chevss442

Turbo wastegate solenoid freuquency

Hi, does anyone know what frequency the PCM uses for the PWM signal it sends to the wastegate solenoid?
04-12-2008, 22:32
More Power

The PCM determines how much on time the vacuum solenoid should receive to produce the required boost pressure. So, on and off time is variable, it's not a constant frequency.

Jim
04-13-2008, 16:17
moondoggie

Good Day!

Yup, the PCM varies the duty cycle feeding the Wastegate Actuator Solenoid. I bet he'd still like to know what the frequency is, however. Unfortunately, I've never had time to scope one...sorry!

BRJ
04-13-2008, 19:55
chevss442

Yes, the signal is a constant frequency that is pulse width modulated (PWM). I measured it with my scope to be about 33Hz. I was just hoping to get a confirmation from someone else to see if that sounds about right.

I converted my truck from the DS4 to a DB2 injection pump last year. I had been planning to convert the wastegate to a mechanical actuator, but have not had time to do anything with it yet. Lately I've been thinking of using the exitisting actuator and making a PWM control circuit to control the solenoid. I figured I'd use the frequency that the PCM uses as a place to start.

Thanks
04-15-2008, 07:00
daustin

With your conversion to a mechanical DB2, i'd just fab or buy a turbomaster spring based controller, get the shorter belt and be done with it. They work great with the DB2's, i've got that setup on my '93 3500. Quick, easy and simple to tune with a boost & pyro gauges.
Don
04-15-2008, 13:45
More Power

Quote:

Originally Posted by chevss442

Yes, the signal is a constant frequency that is pulse width modulated (PWM). I measured it with my scope to be about 33Hz. I was just hoping to get a confirmation from someone else to see if that sounds about right.

I converted my truck from the DS4 to a DB2 injection pump last year. I had been planning to convert the wastegate to a mechanical actuator, but have not had time to do anything with it yet. Lately I've been thinking of using the exitisting actuator and making a PWM control circuit to control the solenoid. I figured I'd use the frequency that the PCM uses as a place to start.

Thanks

You are correct. I read the service training manual for the DS equipped 6.5s, and saw that the system uses a fixed frequency with a varying duty-cycle.

There was a guy in Australia about 10 years ago who built and offered for sale a PWM electronic controller that allowed the user to select the boost pressure desired, then it would attempt to manage for that pressure. I actually got a couple of his units, and installed one on a 6.5 equipped with a GM-8 turbo. It didn't work too well. Its response was slow and way behind real time, which produced an oscillating boost pressure.

Jim