Conversion ratio for engine load% > MAF/HP?

[srm369]

And you should post that log for us to see!

[ttboost]

I took my DV's off the other day during my troubleshooting marathon. Visually inspected them (still looked new) and used a hand vacuum pump to pump them up to about 20 inches and they held....stuck them back on...took about 8 minutes...

[kday]

Well, I guess there are two failure modes for the DVs: they divert air when they shouldn't, or they don't divert air when they should. The latter case is not really a performance problem (especially on an automatic car), just potentially noisy (chufff) and potentially more wear and tear on the turbos. The former case would look like a boost leak.

I think it'd be safe to temporarily block off the DVs and do another data log to see if it's any different. I've certainly done something similar on other cars, though not the RS6.

[Brav]

And you should post that log for us to see!

Which log is that? and what are the pics you tried to post but dont show up? they appear in my qoute

[Brav]

Well, I guess there are two failure modes for the DVs: they divert air when they shouldn't, or they don't divert air when they should. The latter case is not really a performance problem (especially on an automatic car), just potentially noisy (chufff) and potentially more wear and tear on the turbos. The former case would look like a boost leak.

I think it'd be safe to temporarily block off the DVs and do another data log to see if it's any different. I've certainly done something similar on other cars, though not the RS6.

My understanding is that (like on many other turbo Audis) the stock DVs cant hold the higher boost, not from failure but from limits of the design.

[kday]

Hmm. I ran three different DVs in my Ur-S4. The OEM one (forget the Bosch #), a Bosch 710N valve, and a Forge 007. They all held to 24 PSI OK. The 710N unit only lasted a few years before sticking closed (which results in cool rally car noises on a 5 cylinder), which is why I replaced it with the Forge unit. That's just my anecdotal evidence, of course. They are pretty easy to test for leaks though, so I think I'd do that before replacing them...

There is a problem with holding up to high boost if the valves are installed the wrong way, but I don't think they'd even fit that way in the RS6.

[ttboost]

Hmm...I had the 710N's in my 996 turbo at 20psi for 3 years and never had an issue. I have had them in my RS6 for 1-1/2 years and looked at them the other day and they still look new. When it comes to DV's, I won't use anything but 710N's. Just my experience... Maybe at 25-30 psi, they don't or won't last too long? Can't see ever running that kind of boost in the RS6... not enough waste gate...or transmission...

[Brav]

Well I inspected them before and they were fine.. I was just trying to sort my trailing boost issue. Maybe its natural for this map/car... ?

[ttboost]

It seems most every log I have seen has this feature. The ECU requests boost and it takes time to build it, and when the ECU doesn't want it, it takes time to blow off...kinda natural...

[Ghost-]

Brav, I have some news about this problem.
It seems as stated before by other RS6 members, the hot air getting in the engine makes the ECU send an order to avoid potential engine knocking due to the higher probabilities of this with compressed hot air + gas. So, in order to avoid this, the ECU retards the ignition of the air+gas mixture and lowers boost, resulting in less power:

	Timing Retardation	Timing Retardation	Timing Retardation	Timing Retardation	Timing Retardation	Timing Retardation	Timing Retardation	Timing Retardation
TIME	Cylinder 1	Cylinder 2	Cylinder 3	Cylinder 4	Cylinder 5	Cylinder 6	Cylinder 7	Cylinder 8
	°KW	°KW	°KW	°KW	°KW	°KW	°KW	°KW
0.01	0	0	0	0	0	0	0	0
0.34	0	0	0	0	0	0	0	0
0.69	0	0	0	0	0	0	0	0
1.03	0	0	0	0	0	0	0	0
1.37	0	0	0	0	0	0	0	0
1.71	0	0	0	0	0	0	0	0
2.06	0	0	0	0	0	0	0	0
2.4	0	0	0	0	0	0	0	0
2.74	0	0	0	0	0	0	0	0
3.09	0	0	0	0	0	0	0	0
3.43	0	0	0	0	0	0	0	0
3.77	0	0	0	0	0	0	0	0
4.1	2.3	4.5	2.3	6	0	0	0	0
4.44	4.5	4.5	2.3	6	0	0	0	0
4.79	4.5	4.5	2.3	6	1.5	0	0	3
5.13	4.5	4.5	2.3	6	0.8	0	0	2.3
5.46	4.5	4.5	2.3	5.3	0.8	3	0	2.3
5.78	3.8	3.8	1.5	5.3	0.8	3	0	2.3
6.13	3.8	3.8	1.5	5.3	0.8	3	0	2.3
6.48	3.8	3.8	1.5	5.3	0.8	3	0	2.3
6.81	3.8	3.8	1.5	5.3	0.8	3	0	2.3
7.16	3.8	3.8	1.5	5.3	0.8	3	0	2.3
7.49	3.8	3.8	1.5	5.3	0	3	0	1.5
7.83	3.8	3.8	1.5	4.5	0	2.3	0	1.5
8.16	3.8	3.8	1.5	4.5	0	2.3	0	1.5
8.5	3	3	1.5	4.5	0	0	0	0
8.85	0	0	0	0	0	0	0	0
9.19	0	0	0	0	0	0	0	0
9.53	0	0	0	0	0	0	0	0
9.88	0	0	0	0	0	0	0	0
10.22	0	0	0	0	0	0	0	0
10.56	0	0	0	0	0	0	0	0
10.91	0	0	0	0	0	0	0	0

At 4.1 was the first timing retardation at arround 4000RPM, just after the turbos have peak boost.
Supposedly, a positive value means timing retardation (less power) and a negative value means advanced timing (more power).

[Brav]

Looks like your passenger side bank is more retarded than your right... (LOL?). wonder why. my ignition hit -3 in some cases.. actual timing, not adjustment. so must have been a huge adjustment.

[ttboost]

Sign of an aggressive tune. Those are the trade offs. More timing= more power, but the down side is more opportunity to retard this timing in hot weather, bad gas etc.... Less aggressive tune (lower timing) had less power peaks, but a more consistant power (less timing retard) overall.

[4everRS]

Mike's right about that tune likely being aggressive. I wonder why some cylinders are retarding and some aren't. I mean, is knock sensor voltage sending the signal? Or is it EGT's?

[ttboost]

Probably light knock. Some cylinders are more sensitive to heat than others based on the way the cooling passages go...and more sensitive to detonation based on the intake and how the air gets in there with fuel...High EGT's are a result of big boost and heavy load, usually a problem with a truck towing a trailer with a hot tune....not an RS6....

[4everRS]

So, are there are like 3 knock sensor modules right? And they can be cylinder specific then? I just want to understand how that works.

The way the cooling passages run makes a lot of sense.

[lswing]

Brav, how's the tune been sorting? That's a lot of boost you've been running, and i see a few negative timing numbers. I was in that ballpark, but smoothed it out this week by finding the right balance between boost and timing. All other parameters were looking pretty good, and a reduction of boost, along with an increase in timing, brought me from some negative timing numbers to the lowest being 6.

[ttboost]

I would love to know how people are running megaboost without going into limp mode...

[4everRS]

I would love to know how people are running megaboost without going into limp mode...

It's all about requested vs actual. If actual is a certain level above requested, limp mode. If your tuner can set the requested higher and your hitting those numbers, the ecu doesn't have a problem. According to it, the engine is doing what it is suppose to. Last time I saw your logs, before you turned it down, your actual was well above requested.