MoTeC Global Forum

OK another issue...lol My boost signal is erratic. I tried 2 sensors with same result. My intake manifold pressue signal is good. I installed the boost sensor before throttle body. My intake tmap sensor is in the log style manifold. I run a borg warner efr turbo with built in recirculation in the housing. Why is the intake smooth and pre throttle body erratic? I checked all the obvious. anyone had this issue before?

Last season when I ran just the intake sensor the boost signal and control system was smooth and perfect.

another picture with turbo speed and another of last years boost control with only tmap sensor.

Because the system has a different response, you likely need to revisit the tuning for the PID control. That would be Boost Control Proportional Gain, and Derivative Gain mostly.

I would expect the Boost Control Feed Forward to remain the same, but looking at your data, you might want to increase that a bit.

It might also be worth seeing what happens if you increase Boost Filter to say 20 - 40 mS -- it does look like your sensor measures fluctuations at it's current location. Was the MAP sensor filtered?

I had set the filter to 40ms on this run. Would you recommend to try a different location? Maybe at the intercooler tank or how about close to the turbo outlet?

Also, is it acceptable to have these pulses in the signal?

Hi,

Can you turn off the filtering for both the Boost Pressure Sensor and the Inlet Manifold Pressure sensors and see if they both have the same fluctuations in the signal.

How far apart from the MAP sensor is the Boost Pressure sensor? I have seen these sorts of pulsations before when the turbo is running close to surge, the pulses were read on the compressor outlet pressure sensor, but not on the post intercooler sensor as the intercooler was acting as an damper and smoothing out the pulses.

Try turning all of the PID controls off (set them to 0) and just have the boost running off of the Feed Forward table and see if this changes the behaviour.

What is your throttle plate doing at this point as well?

The filter for the tmap sensor was set at 8.0ms and the boost pressure sensor was at 40ms. I will change both to 0 and compare.

The tmap is located about 4" from the throttle body in the intake manifold log. The boost pressure sensor is just infront of the throttle body about 4". So they are around 10 to 12" from each other. This is a intercoolered system.

My turbo is a efr6258 good for 200 to 450hp. My motec m1 indicates 29lbs/min flow at 14.5psi at 120k turbo speed. On this turbo map for a PR of approx 2 it puts it in the middle island area.

In the log posted i have throttle lever and throttle plate logged ans they are both the same and smooth.

Will report back when i can do another test. Ran out of snow here but hope soon to be back at it.

Thanks!

So i ended up solving the issue. It turns out that there is 2 filters under boost pressure sensor and 1 filter for the map sensor channel.

My tmap has a filter of 8ms
The boost system filter is at 40ms
Then, i found boost pressure sensor VOLTAGE filter, and i set this to 20ms and that fixed it all up. I have smooth boost signal and boost system control.

My guess is the voltage input for the boost sensor was erratic because it was picking up the fluctuations in the system. The filter smooths it out and I am good to go.

Just need more snow!

Thanks for the replies!