Down on boost

[LIRS6]

I've lost the sound of the turbos spooling, sensed my boost is down, got following sample logs - peak boost was 1670. Ref MAFs, note bank 1 is consistently less than bank 2.

Any comments / thoughts welcome



time rpm MAF MAF total boost boost
bank 1 bank 2 specified actual

544.6 2160 29.94 42.33 74.08 1040 1010
545.3 2040 29.86 41.03 68.25 1050 1130
546 2000 32.14 44.42 92.03 1100 1190
546.72 2200 49.69 59.64 115.44 1570 1240
547.4 2400 60.56 78.42 139.5 1560 1410
548.1 2640 86.64 71.86 160.89 1540 1580
548.8 2840 80.11 76.5 156.25 1550 1600
549.51 3040 74.42 87.5 169.08 1480 1500
550.2 3280 81.39 97.31 177.33 1430 1460
550.91 3520 76.83 82.56 163.17 1360 1430
551.62 3720 70.25 83.47 121.69 1210 1300


768.63 1280 3.19 4.67 8.28 980 1000
777.02 1880 31.92 37.39 39.11 980 1020
777.72 2600 60.86 77.83 86.67 1430 1080
778.42 3240 126.58 101.08 158.5 1630 1470
779.13 3760 103.19 121.5 231.08 1580 1670
779.84 4200 116.58 139.33 233.78 1560 1520
780.54 4680 143.72 163.89 273.81 1610 1550
781.25 5200 155.14 182.31 314.22 1590 1560
781.97 5720 172.67 202.86 345 1660 1560
782.68 5960 2.17 6.14 364.08 980 1610
783.38 3960 7.67 11.89 20.06 980 1200
784.05 2760 3.47 8.64 15.08 980 1060
784.75 2480 3.72 8.58 12.81 980 1030

830.9 720 3.22 5.06 8.5 980 990
831.6 2000 14.36 14.86 41.89 1250 980
832.31 2760 35.61 46.31 91.78 1620 1130
833 4040 72.92 88.17 198.81 1580 1570
833.7 5440 137.44 142.83 293.44 1670 1550
834.41 5600 166.5 187.53 364.08 1680 1580
835.11 4920 165.25 191.17 299.94 1610 1600
835.81 5440 141.64 166.03 322.17 1610 1540
836.51 5840 161.64 187.53 358.31 1560 1600
837.22 4040 16.17 56.31 24.36 980 1230
837.93 2920 6.33 12.86 19.75 980 1060

1237.98 1760 18.22 20.17 10 990 1010
1238.69 1800 29.17 38.22 53.22 1060 1010
1239.39 2040 40.36 52.33 73.14 1420 1120
1240.1 2440 61.36 75.72 98.97 1690 1270
1240.81 2960 109.11 83.69 151.78 1620 1550
1241.52 3600 102.56 121.58 206.28 1590 1670
1242.23 4160 122.67 138.28 232 1560 1560
1242.91 4440 7.22 11.44 167.58 990 1300
1243.63 4280 37.97 45 21.33 990 1100

1269.51 2960 59.17 76.75 60.72 1310 990
1270.2 3320 119.19 95.53 155.28 1570 1390
1270.9 3880 109.97 126.58 218.89 1570 1620
1271.62 4480 131.53 153.03 246.5 1590 1530

1473.6 3480 12.39 28.08 39.47 990 1030
1474.29 3480 16.58 32.72 50.39 990 1040
1475.01 3520 27.11 43.92 89.83 1020 1060
1475.7 3680 68.56 91.78 190.61 1430 1370
1476.4 4080 113.75 126.89 261.25 1460 1540
1477.07 4600 55 70.78 22.42 990 1220
1477.78 4600 6.58 17.69 25.56 980 1070

[V8weight]

It would appear that you have a boost leak on bank one (passenger side). This could be due to a leaking intercooler, a cracked or loose intercooler hose, or a bad diverter valve. Your peak boost of 1670mb is spot on, as I believe the stock specified boost should be right around 1650, it just looks like it's taking a bit too long to meet the specified boost. All in all, your logs look pretty good, just a slightly slower than normal onset of boost. Also, the bank one MAF g/s will always be lower, but not that much lower. That's what wouls associate the leak with that particular bank.

[RS6Steve]

Look through the Intercooler intakes and see if you can spot any darkening on them, this is a sign off the leaking, usually in the corners. Mine are leaking slightly but not enough for the turbo not to be able to cope with it.

V8 is right, you left looks a little low. Here is what mine look like, not perfect, but not bad either.

434.17 2840 26.58 26.92 ON ON 980 1070
434.35 2920 26.92 26.94 ON ON 980 1070
434.53 2960 27.31 28.17 ON ON 980 1070
434.7 3000 27.64 26.89 ON ON 980 1070
434.88 3040 27.72 28.19 ON ON 980 1070
435.07 3080 27.11 27.89 ON ON 980 1080
435.25 3080 28.17 29.44 ON ON 980 1080
435.41 3120 29.17 30.92 ON ON 980 1080
435.6 3200 34.72 35.36 ON ON 980 1080
435.78 3240 37.08 39 ON ON 980 1080
435.94 3280 39.83 43.31 ON ON 980 1100
436.13 3360 40.83 44.81 ON ON 980 1120
436.31 3400 40.67 43.44 ON ON 980 1140
436.47 3440 40.44 43.92 ON ON 980 1160
436.66 3520 49.06 52.19 ON ON 980 1160
436.84 3600 74.53 74.44 ON ON 1240 1180
437.01 3720 95.92 96.78 ON ON 1520 1270
437.19 3880 124.53 122.03 ON ON 1620 1400
437.37 4040 129.75 140.56 ON ON 1610 1590
437.54 4240 130.22 147.67 ON ON 1630 1680
437.71 4360 140.53 148.06 ON ON 1640 1690
437.88 4520 140.61 159.44 ON ON 1660 1670
438.04 4680 147.28 161.14 ON ON 1680 1650
438.22 4880 151.14 161.86 ON ON 1690 1620
438.41 5040 165.69 176.33 ON ON 1670 1630
2 438.62 5240 172.06 187.33 ON ON 1660 1650
438.85 5440 179.64 195.06 ON ON 1690 1670
439.07 5640 184.44 197.06 ON ON 1720 1660
439.27 5840 188.33 201.92 ON ON 1710 1680
439.46 6000 199.5 208.42 ON ON 1700 1700
439.7 6240 204.83 211.81 ON ON 1700 1720
439.9 6400 209.39 205.08 ON ON 1700 1730
440.1 6480 203.64 216.97 ON ON 1690 1730
440.3 6000 192.92 205.25 ON ON 1690 1720
440.54 5120 162.5 176.86 ON ON 1660 1700
440.74 4800 148.97 155.72 ON ON 1640 1700
440.93 4800 89.06 107.81 ON ON 980 1530
441.11 4760 25.44 49.14 ON ON 980 1440
441.31 4760 9.44 15.03 ON ON 980 1360

[LIRS6]

Look through the Intercooler intakes and see if you can spot any darkening on them, this is a sign off the leaking, usually in the corners. Mine are leaking slightly but not enough for the turbo not to be able to cope with it.

Excuse my ignorance, but how/where do I access the intercooler intakes to view them - removing the lower plastic grills and looking behind the fog lamps? Is that the perspective that you are referring to? Thanks vm

[hahnmgh63]

You can look at them from the front but with the airflow through them the best place to look for leaks is with the lower plastic engine tray removed and to look around the edge of the ducting. You really don't have to look in the center of the intercoolers as everyone I've seen (about 8~10 RS6 intercoolers) have showed the leaking at the welds on the end tanks where the cores are welded to the tanks. So far at least 50%+ of those I've seen have shown signs of leakage.

[DHall1]

I may have a pic of the intercooler corners.

hang on for just a sec



Oppps, not that one. Watch out for 1099s guys. Your going to have them coming out your you know what.

Here this is better. That entire bottom seam where the core meets the end tank of the intercooler. The leaks start in the lower lateral corner. If you look from the front thru your ducting...shine a light back in the lower lateral corner. You will see oil residue if its leaking

[LIRS6]

That entire bottom seam where the core meets the end tank of the intercooler. The leaks start in the lower lateral corner. If you look from the front thru your ducting...shine a light back in the lower lateral corner. You will see oil residue if its leaking

Thanks - went out to car and took below photos.

Passenger side :


Driver side :


So, am I looking at a leaking intercooler??? It would be consistent with v8weight's comment ref MAF bank 1 (pass side).

What's next? Repair, or replacement? Any suggestions?

[hahnmgh63]

It appears the passenger side is leaking for sure and the drivers side from at least the front looks Ok. 3 out of 4 cars I've seen had passenger side leaking or both. Seems like the passenger side has been the most problems, anyone else have this observation?

[ben916]

It appears the passenger side is leaking for sure and the drivers side from at least the front looks Ok. 3 out of 4 cars I've seen had passenger side leaking or both. Seems like the passenger side has been the most problems, anyone else have this observation?

No, but I am about to go out and look to see the same...
Wagners....

Edit:
Ok, I am good, some leafs but that is it...

[JRS-RS6]

Thanks - went out to car and took below photos. So, am I looking at a leaking intercooler??? It would be consistent with v8weight's comment ref MAF bank 1 (pass side). What's next? Repair, or replacement? Any suggestions?

Wow that looks even worse than the one on the passenger of my car. V8weight and I just pulled them both out and replaced them with Wagners. Front bumper gets repainted tomorrow and than back together again.

Search Apikol and Wagner for more information. If you decide to go with Wagners contact 034motorsports dot com mine came out of Germany and with the Iceland volcano delaying all air traffic including airfreight they took just over a week to get here. Arrived at 3:55 PM today.

[DHall1]

Bingo

Pass side has a huge leak.

Will your powertrain coverage cover the intercooler?

If not, I would order the pass side only from genuinevwaudiparts.com and then have a local shop install.

Thanks - went out to car and took below photos.

Passenger side :


Driver side :


So, am I looking at a leaking intercooler??? It would be consistent with v8weight's comment ref MAF bank 1 (pass side).

What's next? Repair, or replacement? Any suggestions?

[LIRS6]

Bingo

Pass side has a huge leak.

What is it exactly that leaks out? Is it oil, and if so, what is oil doing there to begin with? Why wouldn't it just be air leaking?

[JRS-RS6]

It is oil from blow by of the Turbo's. That is why it is part of routine maintenance (15K, 35K, .....) to clean the IC Hoses.

[DHall1]

There is a slight amount of oil residue in the charge air mixture. As it hits the cool intercooler it reforms into oil droplets. Under pressure the crack will spew out the mixture and oil will deposit on the intercooler. normally not a big deal and cleaning your pipes is always a good idea from time to time.

What is it exactly that leaks out? Is it oil, and if so, what is oil doing there to begin with? Why wouldn't it just be air leaking?

[hahnmgh63]

It is oil from blow by of the Turbo's. That is why it is part of routine maintenance (15K, 35K, .....) to clean the IC Hoses.

Technically there is little oil coming from the Turbos themselves, it is oil from the crankcase ventilation that is passing through the Turbos and as DHall1 mentioned, much of it condenses in the intercoolers and coats everything inside the intake system and much of it runs down and settles in the lowest point of the system which is the bottom of the intercoolers and the bottome intercooler hoses. All engines have some blow-by but boosted engines tend to have more due to the extra pressure which causes more crankcase ventilation volume, that is why oil catch cans are a fairly common aftermarket item for boosted cars. I installed two on my RS6, one per bank as there isn't really any common intake point after the PCV inlet into the system to mount a single one.

[4everRS]

Pics? DIY?

Technically there is little oil coming from the Turbos themselves, it is oil from the crankcase ventilation that is passing through the Turbos and as DHall1 mentioned, much of it condenses in the intercoolers and coats everything inside the intake system and much of it runs down and settles in the lowest point of the system which is the bottom of the intercoolers and the bottome intercooler hoses. All engines have some blow-by but boosted engines tend to have more due to the extra pressure which causes more crankcase ventilation volume, that is why oil catch cans are a fairly common aftermarket item for boosted cars. I installed two on my RS6, one per bank as there isn't really any common intake point after the PCV inlet into the system to mount a single one.

[LIRS6]

Crap - my powertrain warranty will not cover intercooler failures. Guess I'm on my own. So ... replace the one bad unit with OEM as suggested by DHall1, or go the route of Wagners? Hmm. JRS RS6 - can you share your thoughts about the Wagners now that you have installed them .. how was the installation process, and do you see substantial benefit from them? TIA

[JRS-RS6]

LIRS6 -- PM replied too.