Help Debugging the High Load OTS tune

[Sassimac]

What sort of boost are you seeing @wot in 4th? You may just need to tweak the wgdc to prevent the the cut/load spikes. With stock car I would assume the wgdc is set higher than would be required with flow mods thus causing overboost conditions.
Do a 3rd gear pull, change the wgdc table and flash, then do the same in 4th gear. I was hitting 22+psi requesting 2.0 load. I edited the wgdc and never saw over 19.5 after that. Now requesting 2.2 I see 20.5 psi tapering down to 16psi.

This leads me to want to understand the WGDC table a little more.

I saw what I would describe as way too high a boost for the CX7 turbo using the WGDC setting for Speed3 high load map as a base. My idea is to wind down the WGDC table to a point where the logged load starts to droop below the load target. This way, the boost pressure is as low as possible to reach the desired load.

Thoughts anyone?

[skiptownmcat]

I don't know the ins and outs of the cx-7 but it must be the same principal. Think of wgdc as a starting point for your boost, too high and especially with flow mods the wastegate can't compensate quick enough causing excess manifold pressure. I would have thought it would be much safer to start with low values and do a couple of revisions to work your way up.

[mituc]

What sort of boost are you seeing @wot in 4th? You may just need to tweak the wgdc to prevent the the cut/load spikes. With stock car I would assume the wgdc is set higher than would be required with flow mods thus causing overboost conditions.
Do a 3rd gear pull, change the wgdc table and flash, then do the same in 4th gear. I was hitting 22+psi requesting 2.0 load. I edited the wgdc and never saw over 19.5 after that. Now requesting 2.2 I see 20.5 psi tapering down to 16psi.

In 4th at 4900-5000rpm, load 2.16, boost spike to 20.4PSI, the wastegate DC was 47.4075%. So almost half closed. Then later the load went down to 1.86 at about 5100rpm and the wgdc went down to 26.0468. So it may very well be this adjustment which I didn't do (I was basically using the OTS map with a MAF cal).
But let me post some logs, because all the numeric values I give you here may not mean much without a context.

almost always with a downpipe, catted or not you will need to upgrade your fuel pump internals!

Yes, very well said, almost always, and it all comes down to the load you're requesting I guess. You can run an open exhaust, if the ECU will never request high load values (which translate into higher boost values at least at low/mid RPM) then you simply not need more fuel (well, of course, the FRP also gives an idea about how thin the fuel mist is which also gives an idea about how well the cylinders are cooled down during the intake cycle).
On the other hand, as I said already, I think it's how this tune works with my mods as it was designed for stock or near stock cars and I never see the FRP dropping below 1600PSI in similar conditions with another tune.

[skiptownmcat]

Well looking at the BCS base table in the high load tune, the wgdc is set for 81% at 5000 rpm. No wonder you're having spikes. You should sort that table out ASAP.

Merry christmas btw!!

[Sassimac]

Can you post a screenshot of your WGDC table?

[skiptownmcat]

Can you post a screenshot of your WGDC table?

Do you mean me? If so I'm using a grimmspeed ebcs so it won't help you at all.
Just do a wot pull and put your wgdc numbers into the corresponding rpm columns in the table and then go from there.

[mituc]

Ok, so here's the tune I used (it's basically the high load tune with a MAF cal and increased idle RPM) and a few logs. The first two logs are 4rd gear pulls (I didn't feel safe to make any 4th gear pulls just yet. That's the first file.

The next 4 files are:
- a 3rd gear and a 4th gear pulls with the versa tune;
- a 3rd and 4th gear pull with the HT tune (next day, similar weather conditions).

What worries me most in the logs I took while I had the versa tune on my car was the abnormally low fuel rail pressure while the load is very high. That doesn't happen when the load is at about the same levels with the other tune I'm using. The most relevant log for this is logis77mtc0385-4th_pull-2.csv where you can see the FRP oscillating between 1800+PSI and 840PSI.
Also, in pretty much all the 3rd gear pulls with the VT around 5500rpm the car was like chocking, I felt it like a load cut as it had the same wavy pull, and then was pulling hard again. I can't see any indication of that happening in the logs now, I'm not sure why, not even a TP closure.

[skiptownmcat]

Btw, load cut = throttle plate closure
I'll look at the logs later if I get time, probably tomorrow though. If you're not seeing any throttle closure, then I think choking you describe is almost certainly the BCS trying to correct the MAP.

[laxplayermjd]

Use a lower off the shelf tune or upgrade your fuel pump. Stock fuel pumps can't keep up having a downpipe.also many blown engines because of this. Cobb makes limp modes map for gen2 ms3,their pumps can't keep up with just an intake.all your problems will be solved.this is of course my opinion based on 2 years of reading the forums. My fuel pump is border line on my 93 octane tune.its next on the list before my downpipe

[mituc]

The autotech internals are on my shopping list already but still, why this doesn't happen with the other tune at similar load values? Is it just because the requested FRP is a bit higher (I think it's 1700-1800 instead of 1670 or something) around the same load values and the pump simply can't keep up and takes a dump?

Skiptowncat, thanks, I didn't notice any significant TP closure, so it may very well be what you say.