DTS dyno surge

[ou812]

Would like to hear from guys using DTS dyno's if they have ever had the dyno surge causing the engine to go up and down in rpm as it's trying to go thru the program? Not only can you hear the engine doing this, but the printed graph shows big spikes or lightning bolt check marks right at 5000rpm...the first pull of the day, on any day it almost perfect, but every pull after that sucks. And it's random, but is now happening every time.

I've looked a few things, just really would like to hear from guys that may have encountered this with their DTS...thank you!

Brian

[mag2555]

One would have to assume that it's reacting to water temp in the brake which would increase the pressure , or fluctuat the pressure seen by the electronics.

[shawn]

Check your water delivery and return. Hoses and filters.

shawn

[Walter R. Malik]

The software is probably not controlling the water to and from the brake correctly.
How it is fixed, I have no idea but, when Superflow took over DTS years ago and implemented their software this problem arose ... they somehow got the software straightened-out.

[gmrocket]

Check your water delivery and return. Hoses and filters.

shawn

I had this problem on a superflow and it ended up the filter collapsed.

[J.J.Hall]

Sounds like low water level in tank, or low feed pressure from supply pump,or not enough load amount in the water break.
I plumbed a large pressure gauge into the room so I could watch it time to time.
That is with a superflow dyno.

[ou812]

Thank you guys...this problem seemed to start when our Controller box failed, had it rebuilt and re installed it...however I came across another rebuilt Controller box and tried it and same thing.

I wondered about the pump feeding the dyno, but pressure maintains at 60psi (where I usually run it). The weird thing is no matter the engine, it's smooth from 3000-4900rpm but at about 5000-5200rpm it starts to surge...and gets worse the more runs I put on it. I also allow some time between pulls, about 4-5 min. and the water temp out of the brake is very close from pull to pull. So not sure if it's temp or what.

Everything works or seems to work fine, until I go to make a pull, and the engine gets to 5K...I guess I can pull all of the water lines apart and re do them...look for a problem. I'm going to take both my controller boxes to another shop that runs a DTS and have them plug both of my boxes in and run them with a known engine to rule that out...or give me the answer!!

[hjallle123]

we have spikes on torq when motor is running bounsing all over
we have change controller box
another computer and program
no rf interference
changed to resistor sparkpluggs
calibrated dyno



but torque keep bounsing allover when starting engine

[drifter]

Do you have a way to lower the water pressure a bit? If so try it at 50psi these pumps flow more water lower then the max pressure when this happens is it peak tq of the engine?

[Scott]

At a guess its your speed controller / load control valve . Either the valve or the software controlling the valve ..
Upgrade the valve to a ADL Depac valve and you'll never look back ..

[BILL-C]

I had a similar problem with my DTS many years ago. Some how a piece of a zip tie got stuck in one of the control valves. Get a couple of rebuild kits for the valves and go through them. There is a re-homing procedure for the clock positions on the valves you need to follow when you put it all back together. You could have plugged filter screens in plumbing also.

[hjallle123]

its when the engine is running the torque bounsing all over from start and on all rpm

[ou812]

The funny thing is, the very first pull of the day, any day, any engine, is almost trouble free...not quite but not horrible...after that every pull goes down hill, and won't repeat, even the zig zag check marks we get will differ in size, and rpm where they happen...but always AFTER 4800rpm!

[williamsmotowerx]

Sounds like a bad rpm pickup sensor. Is there one on the brake?

[ou812]

We replaced it first, no change.