Cruise surge issue

[engr7581]

I can't figure out this weird cruise surge issue. This is on a manual transmission truck and the surging only shows up around 1600-2300 rpm with cruise on. Remove the cruise from service and truck acts normal.

I have tried smoothing the Flow vs current tables, the pedal to fuel tables, and pulse table and I can't get it right. I have searched through this forum and it seems a few others have experienced it.

This is a CSP5 truck but I am only using tune #1.

Thanks for any help!!

[Ghostman]

Ok what I see is it seems to do fine until you get into some boost. Did you hit a hill or something to climb? When the boost comes on that's when it looks like the surging starts. So that would make me think it's boost related. The reason I would assume then the it surges is because it's making you MM3 jump up and down which makes the rest jump up and down. What are the rest of the mods on this truck?

My first suggestion would be to lower your main duration in the mm3 x FRP area that the surging is occuring. Looking at your main duration map vs mine, your duration numbers are way higher than mine are.

My duration table:
19134

Your duration table:
19135


TAKE ALL THIS WITH A GRAIN OF SALT!! I am in no way a professional tuner!! Just throwing out what I see is all.

[tylerltr450]

Ok what I see is it seems to do fine until you get into some boost. Did you hit a hill or something to climb? When the boost comes on that's when it looks like the surging starts. So that would make me think it's boost related. The reason I would assume then the it surges is because it's making you MM3 jump up and down which makes the rest jump up and down. What are the rest of the mods on this truck?

My first suggestion would be to lower your main duration in the mm3 x FRP area that the surging is occuring. Looking at your main duration map vs mine, your duration numbers are way higher than mine are.

My duration table:
19134

Your duration table:
19135


TAKE ALL THIS WITH A GRAIN OF SALT!! I am in no way a professional tuner!! Just throwing out what I see is all.


Wow thats some pw. How hot does that tune get?

[Ghostman]

Wow thats some pw. How hot does that tune get?

Especially be labeled as a 80 Hp tow tune lol.

[engr7581]

It on a fully loaded dyno run it will hit 1350F if left long enough.

Yes it starts to surge at the bottom of hills and at coming off the top of a hill. Basically during transition areas.

[engr7581]

pay no attention to the label it means nothing. The tune has other files in it. I am focusing on tune #1

[engr7581]

Problem solved. It was a faulty cascade valve lifting and reseating multiple times. Found it on return flow data. Thanks to all for the help.

[Ghostman]

Glad you figured it out!