Pacbrake compressor cycling

[mbaston]

I installed my Pacbrake on my 03 today. Is it normal for the compressor to cycle every 5 or 6 seconds when the brake is activated or do I have a leak somewhere.



Has anybody installed the small Pacbrake airtank. The instructions given would have me drill the frame in a way not compliant with Dodge's TSB. Any ideas?



The brake is also drilled and tapped for my pyro probe. Is it really all that bad to have the probe post turbo. I understand it will read a couple hundred degrees cooler but couldn't I take that into consideration in determing when to back out of the throttle?

 

[SRadke]

If your compressor cycles you probably have a leak. Mine will cycle slightly when it is cold (below freezing) until the compressor gets warmed up a little.



It is better to have the the pyro pre turbo. Yes you can take into consideration the diffrence and back out of it but the diffrence is not always the same. In other words, the more boost you are making the larger the diffrence will be. This realtionship is not exactly linear. It's easier to put it pre turbo and read it for what it is.



-Scott

 

[CIverson]

You definetally have a leak somewhere, the compressor won't cycle until the pressure is low and the pressure switch is activated.



I've got mine setup w/ a tank in my toolbox and it works great.

 

[Briman]

I put the small tank on the frame where Pac suggested, I didn't think two 5/16 holes (four actually) would compromise the frame, and you would strip out the bolts (not grade 5) before you colapse the frame.



Anyways, the way its wired up, the pump only goes when the ecm turns the brake to the closed position, so if it's not closed for very long, it will take several closings for the tank to reach 105 psi. I've found on mine (today) that the tank is good for five or six cycles before the pump runs again.



The ECM controller is slightly different than on my '03 in that when the truck comes to a stop the brake will release (turning off the pump). On the '03 (early flash) I had to manually turn the brake off when stopped. The delay duration is shorter as well, have to make snappy shifts or keep the foot on the gas a little bit to keep the brake from cycling.



Get out some soapy water and test all your connections to see if you have a leak or not.

 

[JRG]

It is better to have the the pyro pre turbo. Yes you can take into consideration the diffrence and back out of it but the diffrence is not always the same. In other words, the more boost you are making the larger the diffrence will be. This realtionship is not exactly linear. It's easier to put it pre turbo and read it for what it is.

I think this is a better response than the whole other thread on the subject. Thanks Scott.



JRG

 

[smartineau]

If those couple of little holes in my frame cause a problem, I would have big problems with my frame. I have a 2 1/2 gallon tank and the brake can cycle many times prior to having the compressor come on. to look for a leak mix up some dishsoap and water and apply some at each connection point, you should start seeing bubbles forming.



steve