severely lacking power - any ideas

4.2 V8 40v biturbo - 450 bhp
4.2 V8 40v biturbo - 480 bhp (plus)
batty
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Post by batty » Thu Nov 05, 2009 8:57 pm

okay - that was fun.
here's the log files - all i've done is saved them as .xls and marked with yellow the full throttle portions.
what does it all mean ??
Attachments
LOG-01-002-114-115 marked.xls
(34.5 KiB) Downloaded 49 times
LOG-01-005-054-115 marked.xls
(48.5 KiB) Downloaded 32 times
LOG-01-002-117-118 marked.xls
(64 KiB) Downloaded 51 times
c5 RS6 plus in silver

mattler
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RE: severely lacking power - any ideas

Post by mattler » Thu Nov 05, 2009 9:10 pm

Both my I/c`s are leaking but I`m getting no drop in power??

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Shoppinit
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RE: severely lacking power - any ideas

Post by Shoppinit » Thu Nov 05, 2009 11:20 pm

Batty, what version of VCDS are you using? The labels are weird. You've got "Load" where I've got "Throttle position for example". I was able to know what was what by looking at my logs:

Image

I looked at all your data, and it looks pretty good to me. I don't see the 35% difference in MAFs you were talking about. Like me you're at about 10-15% difference which is normal for the RS6.

You're asking for, and achieving, correct boost levels. Possibly a little late, which might indicate a boost leak. But generally, your figures look very close to mine. I rolling roaded mine the other day and got proper results, but I still feel like the car's not as quick as it should be - could indicate boost leak.

Mattler, if you've got intercooler leaks then it will take longer for the boost pressure to reach specified boost, but you'll get there later in the rev range. That's why it's difficult to detect boost leaks on a rolling road because it's not about how quickly you get to max power output as it would be on the road.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

batty
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RE: severely lacking power - any ideas

Post by batty » Fri Nov 06, 2009 7:36 am

thanks for the analysis. the runs i did last night were max throttle in 3rd gear through the rev range, but didn't replicate the problem i was seeing previously at 2000rpm at high load (5th gear).
i must admit the car seems to be pulling a lot cleaner since the trip to the dealers and although they said they did nothing, maybe they "un-disturbed" something without realising, or did a TBA as a matter of course, or a TCU reset, or......
also the ambient temp is about 10degC lower than a couple of weeks ago.

but overall, the car seems a lot smoother - less jerky gear changes, transmission is holding on to a higher gear for longer before searching for a lower gear under load, etc...

will try to replicate the hunting at 2000rpm in 5th gear this weekend, but overall i think this is a good learning experience rather than a worrying one..!!
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batty
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RE: severely lacking power - any ideas

Post by batty » Fri Nov 06, 2009 7:42 am

and i'm running vagcom version 409.1 as it came with the cheapo ebay lead and works okay.
will try 908.1 and if it runs okay, will change my license over.

also - there's a suspected intercooler leak (i think deanobeano said unit20 spotted it, but wasn't excessive), and i'm sure the DV's are still the original.

would be nice to have the "consumable" sensors and equipment replaced under warranty but could be tricky convincing Audi its essential....

many thanks
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RE: severely lacking power - any ideas

Post by Shoppinit » Fri Nov 06, 2009 9:37 am

You can test the DVs easily enough by removing them and sucking on the little nipple. You will see the diaphragm lift and drop down again when you stop sucking. But if you're going to remove them, you might as well put now ones on. They're about £20 each.

Mattler was working on an alternative source for IC. Any news on that?
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

MoRS6+
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Re: RE: severely lacking power - any ideas

Post by MoRS6+ » Fri Nov 06, 2009 10:40 am

batty wrote:..i must admit the car seems to be pulling a lot cleaner since the trip to the dealers and although they said they did nothing, maybe they "un-disturbed" something without realising, or did a TBA as a matter of course, or a TCU reset, or......
Exactly the same here. Took car to MRC for 20k service and when I drove it back home was much, much quicker. In fact I'd say it is ballistically fast now. I also wondered whether they did the resets on various control units as part of the service. I'll have to phone them when I get the chance! Of course it could be that the plugs were past it and the oil was past it etc. etc. or maybe there was a loose hose somewhere, but whatever they did, I ain't complaining!

RS6-4dr911
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RE: severely lacking power - any ideas

Post by RS6-4dr911 » Sat Nov 07, 2009 5:49 am

FWIW, I think I'm in the same boat. Have consistently logged high 5's 0-60. I've logged the above data, not sure how well it fits spec's, but the main thing I've been thinking is very similar to the above re: bad MAF's since I had a 2.7T several years ago that was a pig off the line, replaced the MAF and all was well, there was no CEL (MIL) then or now.

I'm also sure (in spite of the dealer saying "all is well") that I've got an IC leak since I see the tell tale signs of a dark residue at the bottom of the passenger's side unit. So it could be either. Boost never seems to make it fully to the requested level but it's close.

What you describe - bog off the line then seemingly proper performance is exactly what I feel as well.

Let's keep each other posted within findings and results.

batty
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RE: severely lacking power - any ideas

Post by batty » Sat Nov 07, 2009 9:09 am

i've just joined the rolling road meet (up north) for next Sat - so will be interesting to see what we find.
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RE: severely lacking power - any ideas

Post by Shoppinit » Sat Nov 07, 2009 9:14 am

Cool. Good thinking. A couple of weeks ago, I got full power, despite my problems. Will you be able to log values at the same time? Mine was pulling ignition on most cylinders on the power run. NO idea why. Must have been bad fuel. Still got good results though.

RS6-4dr911: Both MAFs bad at the same time? Possible, but wouldn't the lambda sensors then correct for it? If the MAFs were completely off then the lambdas should throw an out-of-bounds error. I think my MAF values are good because of the power results. I can post them later for comparison. Have you got any logs we can peruse?
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

batty
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RE: severely lacking power - any ideas

Post by batty » Wed Nov 18, 2009 2:02 pm

okay chaps - i need to draw my paranoia to an end.
the results from the rr session were totally as expected for a std car.
i had the guys at unit20 check the car over beforehand - no boost leaks, DV's okay, no fault codes, MAF's reading fine.
Grizz also took it out for a drive and said it felt fine.
he also commented that the std cars don't produce high torque low-down, in an attempt to protect the transmission.
whereas remapped engine produces high torque early on.
i guess that's the key statement, and it must mean that the RS6 i took out from the dealer must have been remapped, as it was savagely quick even below 3000rpm.

so i'm happy with the car now, and will ready myself for a remap sometime in the future...!!
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RE: severely lacking power - any ideas

Post by Shoppinit » Wed Nov 18, 2009 2:58 pm

Cool. Glad to hear all is OK. How about posting the RR results? What HP / torque did you get?
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

batty
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Post by batty » Wed Nov 18, 2009 3:13 pm

okay - here's the graphs
Attachments
scan0003 mod.JPG
scan0001 mod.JPG
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Cornishmoocher
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Post by Cornishmoocher » Wed Nov 18, 2009 8:49 pm

Hi matey, these cars are good at increasing paranoia levels!

Saw your graphs over on SRS and now here, they look good to me

Griizzzz and Lee really know there stuff and love our cars as much as we do.

I trust them 100%, hence why I left my car for him to run at the RR- thats a thing that just wopuld not happen anywhere else i promise you!

Sorry I couldn't be there ( iwas embarresed about how dirty it was!)
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Post by johnny11 » Wed Nov 18, 2009 9:19 pm

i was at unit 20 today and saw your 1 moocher

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