TouringBubble

iTrader: (2)

EDIT :: Mrfred found the issue. I had my boost control set to follow 6B42 but I was logging 6B48. My solutions were to:

A) Log 6B42
B) Change the load reference for boost to 6B48

6B48 fluctuates with temperature, so the warmer temps caused the difference between the target and actual load. The 6B42 load value was actually hitting target.

I've since changed back to direct boost control based on the MAP sensor to get rid of this problem. I'm still logging 6B48 load since it seems to be in line with my timing map when the temps change.

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Guys, I went out for tuning tonight to try out the flat BWGDC curve I've been testing and came across a weird occurrence. Apparently, my target boost is no longer equal to what is defined in my map. The last time I was out logging everything was fine and tonight my target boost seems to be around 20% load less than the map.

Since the last time I tuned I've added the WG spring mod (add a second spring to WG flapper) to hold more boost up top. My assumption was that the spring mod would only reduce WGDC% needed to achieve a given boost/ load level. Other change was new wheels and 245/45/17 tires ... that should only throw the speed off a little, but I thought I'd mention it to cover my bases.

Here is one of tonight's logs ... I was planning to tune out the spike but ran in to this issue ...



As you can see, the TBEC stabilizes the boost after a little work, but never attempts to get the load within 20% of target. I first thought this had something to do with my TBEC settings since I've got the super negative areas dialed down to small numbers to fight spikes. However, the WGDC is being corrected down to match this odd load target.

Here is a log from the other week with very similar settings ... it did have more TBEC correction for low boost and a correction delay of "1."



And here are my boost control settings used that resulted in the odd load target. I double checked the values used against Mrfred's write up and noticed that I didn't have MUT8B defined, but it never caused a problem before ...

RazorLab

iTrader: (8)

Didn't we just talk about flat wgdc curves?

I could have sworn I brought up an issue like this with trying to get the TBEC to control such wide fluctuations. Looks like it spiked then error correction brought it down hard, then it was too far down, then it brought it back up, was too high, then down again, and on and on.... It was over your 265 load target at 3000-3500rpm, then under your 262 target at 3750. It's being put into a vicious cycle by the looks of it.

I'm curious, with your setup, with error correction OFF, does 50% wgdc at 3500 hit your desired load target of 265? Or is it over it? If you effectively added more "pretension" to your WGA with that spring mod, it will give you more boost for the same WGDC.

What are those 6EE2 tables?

TouringBubble

iTrader: (2)

6EE2 tables are the load error addresses ...

I'm not worried about the fluctuation, I'm worried that the actual load is way off from desired after the large load fluctuations stop. In the second graph there is a lot of wobble in the boost curve, but it is actually aiming at the correct load value.

50% BWGDC is around where it needs to be for my desired load ... at least pre-spring addition. I was running about 58% WGDC for that desired load previously when I had the BWGDC curve tuned precisely. I was using 50 BWGDC for safety when first trying out this flat BWGDC method.

Just to note ... both graphs shown use a flat WGDC curve and similar TBEC tables. The secong graph (correct load target) had more + correction for low load (-20, -17.5, -15).

One other thing that may or may not be related ... I took my car to the tire shop yesterday and enabled my valet rev limit. When I disabled it, I accidentally held the clutch for a short time along with the accelerator (I was in traffic). I know it seems like a long shot, but this seems to me like an issue with the ROM data and the valet limit may be related. I'm going to cycle the valet rev limit today and see what happens.

Also, last night I did try loading a ROM with a tuned WGDC and had the same issue ... load was still ~ 20% below target. This was very odd because with the spring added the tuned WGDC would have actually been higher than needed. TBEC was still enabled and pulled the load way down just as shown in these graphs.

MR Turco

iTrader: (16)

Edit: nevermind i responded looking at the wrong graph. Very odd indeed.

burgers22

If I'm reading the graphs correctly, the WGDC% in the top graph is very slow to incease, in the lower graph the WGDC% moves very fast to compensate for the under boost, after correcting the over boost spike. I agree with razorlab, you need to look at getting the BWGC in line with your target boost, 50% BWGDC seem very low to hit the required boost at 3.5k RPM. I had a similar experience to you when setting up my 3 port.

MB

TouringBubble

iTrader: (2)

The WGDC is slow to increase because it seems to be aiming for a different load target. Look at the graph again below ... specifically at the place I've highlighted ...



In the highlighted area you'll see that the WGDC actually applies negative correction to lower the boost just as if it had overshot the load target. This is why I feel that it's aiming for a different load target.

Again ... this isn't about spikes or unstable load/boost. I can guarantee that if I dialed in a really nice BWGDC curve and added the error correction back in the situation would still exist. As mentioned earlier, I did load a ROM with a tuned BWGDC curve and got the same results. The problem lies in the TBEC actions or the load target, not with the BWGDC.

MR Turco

iTrader: (16)

TB I would try to reset the ECU and see if it goes back to normal. Then try the valet mod again and see if anything changes.

lemmonhead

that error corrections looks way wacked I would increase compensation a lot. Also why so much MIVEC at 6,000+ RPM. its pointless since the exhuast pressure is higher than the intake, with so much overlap at that point the exhuast is just being pushed into the intake path.

TouringBubble

iTrader: (2)

I cycled the valet mode this morning and it doesn't look like it helped. I've considered running ScanTech to clear the readiness codes and such as well as disconnecting the battery when I get home this evening. I've also disabled the Tephra mods as part of the troubleshooting process, but I haven't flashed that ROM to the ECU yet.

Lemmon, I haven't finished tuning the TBEC table yet as stated in the first post. I was testing the possibility of using a flat BWGDC profile when I encountered this issue. when I get the WGDC aiming for the correct target again I'll continue tuning the TBEC table.

My car doesn't seem to mind the advanced MIVEC after 6000 RPM. I've tried a many different MIVEC values on the high end and these settings seem to provide the best airflow vlaues. I'll look in to it again though after this issue is resolved.

TouringBubble

iTrader: (2)

Also guys ... I'm not sure why I didn't think to mention this ... my car was in the garage without a battery for a week just after I made that 2nd log I posted. Could that have any affect? I wouldn't think so since the data is all stored in the ROM itself and I've flashed it a few times since. All of the readiness data should be okay since I've driven the car about 50 miles since putting everything back together ...

Any thoughts? I'm just trying to give all of the information i can so we can try to track down the source of this issue ... Thanks for all of the help and comments.

burgers22

Yes, I agree that your analysis make more sense than my first view, and all the other data shows a significantly lower air/fuel flow.

Have you ruled out a mechanical problem with the spring?

MB

TouringBubble

iTrader: (2)

Not yet ... that will be my next step after ruling out the electrical possibilities. The logs don't seem to support the spring being the issue. The spring is also a PITA to take on and off ...

I'm leaning heavily toward something odd with the ECU after not having power for so long. Like it is thinking "Woah ... I'm not sure everything is good to go yet, so I'll just hold back a little." Maybe someone who knows the routines better could elaborate on this possibility.

My logs this morning seemed to show a little less difference (maybe 15% to 18% off) between actual load and the defined target, but I honestly wasn't able to log enough data to really come to a conclusion since I was in traffic.

roger smith

iTrader: (4)

My guess is it's having trouble reclosing the wastegate because the spring is stronger. From the graph it seems fine until correction takes place, and after the initial correction it's unable to return to where it was before any correction took place (because of changed wastegate behavior).

So maybe you need to change your error correction values. I just don't know which way, more or less in the values.

burgers22

BTW, why do you think having an extra spring on the WG will aid in holding boost up top ( I understand the mechanics), do you have evidence that the wastegate is actually being forced open at high revs?

MB

TouringBubble

iTrader: (2)

The spring tension actually helps close the wastegate flapper. So, if the was a control issue caused by the increased tension, it would likely cause overboost and not a lower boost.

Yes, the graph does seem fine until the correction. I wondered about that as well. The problem could be that the -10 to -15 area of the TBEC table just aren't working enough to correct for the low boost situation, but that doesn't explain the negative correction at 4500 RPM. Also, I did load a map with more correction in that area and it didn't seem to make a difference.