Boost vs Drive. Does this look right?

4x4dually said:
It better not freakin' be HX35 numbers. LOL

I've heard about folks putting a potentiometer on the AIT sensor and maybe that will fool the ECM into adjusting timing. Seems a little....well...southern Eng to me, but maybe I'll have to try it.
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It's $5 @ radio shack and about 10min to install. I know they work on gas vehicles so they should work for our trucks. My tuck is in the shop, but I'll look in the manual when I get it back to see if there is an ohn range listed. Are you really going to do it? If you are then I'll wait and see what you find out. If not I might try it...
 
I'm going to tinker with the wastegate before I jack with electronics. I got pots all over my office. Surely I have something that will work if I need it.
 
Really good data Jory. Do you have the stock cam data in a similar situation? It appears that in 6th when drive drops that the wastegate if finally opening all of the way which is theh big drop for a second until pressure can normalize.

On the pull around 2100-2500, it looks like since you sampled such a small part that the pressure rise is the individual exhaust pulses as the exhaust valves open.


At that rpm the exhaust valve will send about 20pulses per second to the turbo, 10(if I'm thinking correctly) on each side of the divider. If you are sampling at greater than 10hz you should be able to see the pressure rise and fall. The earlier you open the exhaust valve the higher the pressure pulses will be at the peaks. Can you give us more data on the sampling?

To truly understand all of the data, it takes more channels of data and better sampling to get the resolution needed to see what is going on. When we are testing cams and head data, we use more channels like a turbine speed senson and IAT to fully see what is going on. A linear potentiometer measuring wastegate travel, I think would explain that dip
 
4x4dually said:
I'm going to tinker with the wastegate before I jack with electronics. I got pots all over my office. Surely I have something that will work if I need it.
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Let me know if you try it. If I ever get some spare time I might mess with it...
 
Well that was a failure. I tried to log this morning since it is now 21F outside. Fluttered like a SOB but the file isn't right. I don't know what happened. I'll try again.

To be clear: This has been an issue for three+ years with the stock cam, it is not indicitive of my new Hamilton Cam. If anything, it is a tad better, but not gone. :D
 
Jory I would think the higher dp is due to the turbine being smaller. Larger turbine and your dp will decrease due to higher turbine flow. As far as the fluttering it could be a turbine issue as well, the colder air is more dense so maybe it is thicker to bite through for the blades and the smaller turbine does not have enough mometum/ force to counter the wheel trying to turn the other way.
That is all speculation though
 
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Zach,

Here's a new plot of the same data, but showing the actual time in seconds on the x-axis and the RPMS. PSI scale on left, RPM scale on right. The fastest I can log data is every 20mS with this setup; hense, the .02 increments. The data inbetween points is interpolated using LOESS in excel.


FlutterPlotII.jpg
 
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PM me the details and what improvements there are...out of curiosity. I can be persuaded pretty easy. :D
 
Zach, would the loging of the "engine timing" help? I can read it with the display, but the ECM isn't broadcasting the data. I'm going to try to enable the broadcast of the timing (what ever data it will give me, it is a crap shoot) with a Cummins Insite or possibly the DRB tool. We'll see in a few days when I can get to one of these tools.
 
SHughes said:
Could you possibly have an instrumentation problem???
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I'm working on that too. I've got some new sensors so I'm going to swap them out one at a time and make sure everything is reading correctly. The recorded data is jumpy and I don't like it. It shouldn't be reading every 20ms (5 times second). Boost pressure isn't digital, it is analog. The graph should show this.

I'll mess with it and take another reading. I got some new parts just last night at 10pm.


Sidebar: Would it help the drive pressure reading to extend the tube into the exhaust manifold and put a really short 90 or 60 or even a 30 deg bend on it so the air is being driven into the tube? Right now it is perpendicular to the air flow. Would this cause a venturi effect and try to keep the tube from pressurising? Think the readings would be higher yet?
 
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