I have been doing more tuning and recently experienced a dip in the load curve. It will peak at ~280 then dip down to 240 and then come back up to 260 before tapering off. This happened on every log now and it never used to happen.

I think, but am not sure if this is becuase of variations in boost. IF you look at the blue line in the graph which is boost, you will see it also dips down. I am working on fixing this but do you think the small dip in boost would cause a drastic change in load?

Here is a picture of what I mean

 

boost leak is my first guess. check all your couplers.

 

the TBEC map is causing that. I've been fighting that effect ever since the stock ECU solenoid control mods came out.

Basically, if you dial in an exact WGDC curve your boost is golden. You can then turn on TBEC and all is well. but, with changes in weather and such that WGDC curve is no longer accurate since WGD% will increase/decrease to meet the desired load/boost with different air density.

At this point, the TBEC table can correct for the difference, but it doesn't always do so smoothly.

The TBEC table is an offset of the WGDC curve, so it doesn't exactly work like closed loop control. Let me toss out some examples ...

WGDC = 60
TBEC = +2 to reach desired boost/load

WGDC goes up to 60.5, TBEC is still +2 ... so you are at 62.5 WGDC.

This problem occurs when the TBEC table and WGDC curves are essentially canceling each other out. the WGDC raises by 1% and the TBEC corrects with -1% ... At this point the load/boost error has to get far enough off for the TBEC to overcome the changes in the WGDC table.

 

Thats just from using ECU boost.

 

I noticed a 9 I have been tuning is doing about the same thing. Its using a hallman MBC.....

 

do you log boost ?? Usually it has to do with boost. The boost will spike, dip and then go back up, making the same thing happen to the load.

But the OP's log shows the boost curve and hit has not dips, so I dont know why load would......

 

Look closer at the blue trace, there is a dip in boost that pretty much correlates with the dip in load. I will have to try and tune boost to be a bit smoother.

I thought it was boost related, thanks to other ECU boost users for confirming this.

 

But it looks like your dip in boost is minimal. Usually its a bigger dip that causes that kinda dip in the load.

Ill dig up some logs with similar behavior later

 

cool thanks. Although the scaling might be a bit deceiving, the load is only varying by around 20 which is not that bad. Also I should mention that I have the load offset by -100 so that 180 on the graph is really 280.

I found another log where the load goes wacky but the boost does not really seem to match the load as well as the first graph.

 

yeah, that load dip will only be around a 1.2 psi drop. Barely noticeable on that graph.

 

Perhaps when boost hit's at peak load the pressure is there but the airflow isn't. A log of airflow would confirm that

The second one is the same dip/rpm. Must be different gear

 

I'll log airflow next time. I don't have the 2 byte setup but for now just the normal one.

 

I did another log with airflow being logged.

The boost is smoother on this run but the dip still happens....

 

Not to counteract you, TB, but in my boost tuning experience that spike/dip scenario was caused by the boost limit table, not TBEC. When I disabled the boost limit, that no longer occured, and I could tune boost with WGDC and TBEC without the dip.

 

Interesting ... I'll look in to it. If that's the case, the boost limit table does more than we expected ...