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ECMlink What causes noisy airflow in the upper RPM band to redline?

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@DSMPT Hiroshi have you seen this pic? This is Justin's boost control setup.
He posted it in his build thread.

EVO boost pill in a 2G:

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No Gary, I hadn't seen the post. I was assuming something different.
 
Just for others coming across this to understand, the factory 2g solenoid is a bleed of solenoid. Meaning in factory setup a line from the compressor housing runs to a T.

One side goes to the wastegate actuator and the other to the boost control solenoid.

The other line off the solenoid goes to three intake post MAF and pre turbo.

The solenoid is used to increase turbo pressure by bleeding off pressure from the wastegate actuator line. So the factory ECU increases the duty cycle of the solenoid to increase boost pressure.

So in a factory style setup if the boost solenoid was never activated (0% duty cycle) this would result in full pressure to the WG actuator which would result in minimum boost.

For failure to result in max boost red/yel wire going to pin one of the solenoid would have to be shorted to ground causing the solenoid to stay open all the time or the solenoid would have to fail open mechanically. This would result in max bleed off pressure from the WG Line.

The solenoid should have an internal resistance of 36-44 ohms @ 68* F.
 
There was a confusion going on. Just to clarify.
When people tell to turn off boost controller, it means we make the wastegate to see the pressure without restriction to allow it to work only with the gate spring pressure. Does not matter what setup we have.

As I mentioned that it would depend what solenoid and hosing you have but generally when you turn off aftermarket controller with common hosing, the boost pressure goes directly to wastegate after turning off. That's how it is designed for safety purpose.

In case if wastegate wouldn't see the pressure after turning off, like @Justin DuBois case, then just simply run a pressure line to wastegate, that's what exactly turn off boost control means.
 
GM3BAR
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ZT-3.5BAR (AEM3.5Bar Silver body)
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The MAP sensor is the only difference between the logs. (The pictures are farther apart in time)
 

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That pretty much fixed it didn't it? Your ZT-3.5 Bar line is a lot less jaggy than your previous MAP lines.
The only really jaggy lines I see now are HP and Torque and I normally don't look at those. I don't know what they are calculated from so I don't know if they are anything to care about.

If I wanted to nitpick I'd say your ZT-3.5 Bar line still has a zig zag up and down of about 1 psi (peak to trough) which on your ZT 50 psi sensor is a volt range of .08 volts. In my logs my MAP sensor on a pull like that will either have no up and down or it will be an up and down of 0.4 psi which on my AEM 75psi sensor is a volt range of .02 volts. And that .02 volts is the resolution of the ecu/ECMlink. The voltage steps can't be any less than that no matter what the sensor. So I don't know, maybe there is still something going on a little bit.

But holy cats, the GM3Bar zig zags in your 12.06-04 log are up and down over a range of 4 psi ! (at around 788sec in the log).
So this latest log is way better.
 
With the sensor installed directly into the intake manifold, thus no rubber vac line to act as a filter, I wonder if the pulses of intake air are causing the jaggedness you are seeing. The intake valve events mean the intake manifold isn't at 12 psi flat all the time but is actually jumping up and down all the time as intake valves open to relive pressure into the cylinders and close building pressure in the intake again. Without a longer rubber line to dampen some of those oscillations maybe that is partially what you are seeing?

As I was doing some research on my Haltech swap I stumbled across this paragraph:

"MAP sensors themselves are fast, but to be able to have a useful MAP sensor reading, a significant amount of filtering needs to be applied. The pressure in the intake varies throughout the engine cycle as each cylinder does its intake stroke, so at the MAP sensor signal must be averaged over at least one cylinder period. The Nexus ECUs average the MAP signal over either 1 or 2 cylinder periods."

Just throwing something else out there as you clearly reduced the signal oscillation with a sensor swap so the above can't be the entire cause but may be a contributing factor depending on how stock ECUs handle the MAP readings.
 
With the sensor installed directly into the intake manifold, thus no rubber vac line to act as a filter, I wonder if the pulses of intake air are causing the jaggedness you are seeing. The intake valve events mean the intake manifold isn't at 12 psi flat all the time but is actually jumping up and down all the time as intake valves open to relive pressure into the cylinders and close building pressure in the intake again. Without a longer rubber line to dampen some of those oscillations maybe that is partially what you are seeing?
The GM3Bar was connected with a hose at this spot, about 8" of it - and the GM sensor had the noisy data over 6K. If the hose was helping, it wasn't helping enough.

As I was doing some research on my Haltech swap I stumbled across this paragraph:

"MAP sensors themselves are fast, but to be able to have a useful MAP sensor reading, a significant amount of filtering needs to be applied. The pressure in the intake varies throughout the engine cycle as each cylinder does its intake stroke, so at the MAP sensor signal must be averaged over at least one cylinder period. The Nexus ECUs average the MAP signal over either 1 or 2 cylinder periods."
This makes sense - the data noise is happening high in the RPM band. I think the GM sampling, or filtering, reaches a harmonic sympathy above 6K. Below that the data from the sensor looks good.
Just throwing something else out there as you clearly reduced the signal oscillation with a sensor swap so the above can't be the entire cause but may be a contributing factor depending on how stock ECUs handle the MAP readings.
(Thumbs Up)
 
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Here we go, all nice and calibrated with a huge boost spike to 29psi.
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I even put in a few more cell updates with this data. The new sensor is smoother from 6-7k rpm.
 

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Couple things I notice from the log above.

On timing, you want it to be lowest during peak torque, then ramp it up to the highest you can get away with at redline. Yours are 1000rpm apart right now.

Also, your target a/f ratio table - my car never ran different going from 11.5 to 10.5. It actually liked it nice at fat in the lower 10s as the extra fuel quelled out minor knock, which you have. Maybe try to mess around with the A/F table in DA, you can always revert - and making it richer certainly wouldn't have a risky downside anyways. Easy experiment. I also see *the jagged* happens after a little knock is shown. Probably zero merit to it, but something to just look at.

Pump gas sucks there is no way around that but if I did it again on pump gas I'd make it as rich as possible through a clean pull, do timing as I said above, then up the timing in the 'dip' aka at peak torque and see how high up I could get it.
 
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