Shoppinit wrote: ↑Wed Jul 17, 2019 9:00 amYeah, it makes a lot of sense. There will be other influencing factors like air flow inertia and ducting geometry, but essentially, thinking about it logically, the pressure should be the same more or less everywhere.
By measuring the pressure very close to the compressor, you might be able to detect differences in performance, but it's probably not likely to bear much diagnostic fruit. Probably not worth it, especially given the difficulty of measuring the other turbo.
Right, that was I thought too, thanks for the confirmation!
Turbo imbalance could be coming from wastegate actuator, preload or incorrect gate operation (sticking, not sealing, etc.); or exhaust blockage.
I think this summarises well the different routes that still need to be explored (along with the possible air leak scenario)
I tend to agree with ajc. More likely to be a wastegate issue than exhaust.
Thinking aloud here... if there was a partial blockage, that would affect turbo performance, but also would suffocate the engine at higher revs. Aren't you seeing fuelling problems at higher revs?
I'm not sure if I interpret fuelling problem correctly, but except when I'm on e85 I don't get any lean warnings (probably due to the oem pumps / injectors limitations). The engine used to feel a bit congested but that was before my recent pipes/hoses cleaning campaign; now it's about a slightly rough idle and mostly a lack of power at most engine revs. Does that answer the question?
One thing you can check is the EGT. See if you are getting different temps, especially after a good run. The thinking is that is gas isn't flowing as well, then the temps will be higher. Or lower. Either way, could be useful to compare to the other bank.
I suppose you mean the temperatures as seen by the lambda sensors? Those exhaust temperatures have been checked perfectly aligned during a recent visit (2 weeks ago) to my tuner. So good call indeed, but doesn't seem to be a clogged exhaust issue. Or?
Do you know if the car has ever had a new turbo? You're supposed to change them as a pair but since they are expensive some people only change one.
I would have liked to have a full car history, but that's not the case and a suppose I won't have a MAFs discrepancy if it was perfectly maintainedSo in short I can't tell about the turbos. Although I'd like to upgrade them at some point with hydrid designs for better reactivity, I confess I'd prefer a quick and cheap fix for those at the moment. Those cars drain your wallet like mad, and I'd like to spread the expenses a bit...
Fuel Pumps
Re: Fuel Pumps
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Re: Fuel Pumps
Thanks for joining forces!
I also think this is a very sensible scenario, but how shall I address this? What I'm going to try is to fiddle with the turbo actuators in place (more hoses cleaning, lubricate what's accessible, etc.) but if it's not enough, the next step is unfortunately to pull the engine out of the car. In such a case I won't bother to repair the old turbos but I'll buy those hybrid ones I mentioned earlier. Open to any suggestions BTW..
Last edited by Classik on Thu Jul 18, 2019 6:08 pm, edited 1 time in total.
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Re: Fuel Pumps
Rough idle suggests air leak. I can't see how a dodgy turbo / actuator / wastegate would cause noticeable problems at idle.
Get some of that VW ignition inhibitor spray and give it a go. I'll be curious to see if it works well.
Also, it's a long shot, but check the master vacuum pipe to the brake cylinder for damage / cracks and leaks.
Now that you've fixed the non-return valves etc, might be a good time to try another boost pressure test.
And there's the smoke machine test.
Plenty of things to try before pulling the engine.
Get some of that VW ignition inhibitor spray and give it a go. I'll be curious to see if it works well.
Also, it's a long shot, but check the master vacuum pipe to the brake cylinder for damage / cracks and leaks.
Now that you've fixed the non-return valves etc, might be a good time to try another boost pressure test.
And there's the smoke machine test.
Plenty of things to try before pulling the engine.
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."
///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."
Re: Fuel Pumps
Also worth doing a compression test.
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."
///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."
Re: Fuel Pumps
Shoppinit wrote: ↑Thu Jul 18, 2019 4:24 pmRough idle suggests air leak. I can't see how a dodgy turbo / actuator / wastegate would cause noticeable problems at idle.
Get some of that VW ignition inhibitor spray and give it a go. I'll be curious to see if it works well.
Also, it's a long shot, but check the master vacuum pipe to the brake cylinder for damage / cracks and leaks.
Now that you've fixed the non-return valves etc, might be a good time to try another boost pressure test.
And there's the smoke machine test.
Plenty of things to try before pulling the engine.
Thanks for the updated To-do list, I have a full time job equivalent of testing on my return from vacation.
Regarding your first point, to be crystal clear idle is not that bad, but it's just not butter smooth as I've seen in other rs6 c5. Am I wrong to believe that if one turbo actuator is say stuck half opened it would inject more (admittedly metered) air than needed in the engine and could lead to the not-so-great idle condition? Anyway I'll try this leak spray, I'm intrigued too.
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Re: Fuel Pumps
If a wastegate is stuck open then exhaust gas will bypass the turbine to a greater or lesser extent. This will cause the turbine to spin less than the other bank resulting in less air being drawn in. Question is, how much effect does this have at idle.
Maybe I'll try to force open one of my wastegates if I can get to it to see what effect that has on the intake masses.
Maybe I'll try to force open one of my wastegates if I can get to it to see what effect that has on the intake masses.
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."
///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."
Re: Fuel Pumps
I'm not sure how, or if, that would affect idle quality. I can't see why it would if the trim is OK. Does it idle the same on the standard map as with the E85?
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."
///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."
Re: Fuel Pumps
Yes, those wastegastes definately need to be checked and tested, will do first thing on my return.
Yes, trims are perfectly aligned so go figure. In response to your question on maps, no I can't draw any conclusion when comparing e85 and standard maps/fuels, they feel the same at idle to me.
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Re: Fuel Pumps
As promised earlier, here are some pics of the intake manifold, the rusty seals, the old non-return valves, and broken jet pump :
Last edited by Classik on Wed Jul 24, 2019 12:06 pm, edited 2 times in total.
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Re: Fuel Pumps
And while we're at it, I can't refrain from sharing some of my new daily V8. No I haven't sold the RS6 (maybe I should), but we've been renting this barge for 2 weeks for our holidays in Canada.
All I can say is its big (really big) and confortable (we are 8 people plus luggages in this car!). Don't ask about the driving experience, it's just well, awfull if you're after any sort of sporty sensation, but I kind of like the experience, the distanciation between the road and the driver's seat, a feeling of 'I'm not really there driving this thing' as if you were in your sofa at home playing a calm car video game. Enjoy the pics!
All I can say is its big (really big) and confortable (we are 8 people plus luggages in this car!). Don't ask about the driving experience, it's just well, awfull if you're after any sort of sporty sensation, but I kind of like the experience, the distanciation between the road and the driver's seat, a feeling of 'I'm not really there driving this thing' as if you were in your sofa at home playing a calm car video game. Enjoy the pics!
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Re: Fuel Pumps
It's like something from another era.
Good for unpaved tracks, though. Or "country roads" as they call them. Some great fun to be had on those if you've got a four wheel drive with good ground clearance. I did hundreds of miles on those kinds of roads in Colorado / Utah and you get to see scenery you just couldn't get to in a normal car. Worth seeking those kinds of itineraries out.
Good for unpaved tracks, though. Or "country roads" as they call them. Some great fun to be had on those if you've got a four wheel drive with good ground clearance. I did hundreds of miles on those kinds of roads in Colorado / Utah and you get to see scenery you just couldn't get to in a normal car. Worth seeking those kinds of itineraries out.
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."
///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."
Re: Fuel Pumps
Actually ground clearance is not that high so I wouldn't dare to try too rough tracks. A bit like the worse of both worlds if you ask me, but nonetheless fun enough (for two weeks).
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Re: Fuel Pumps
Hi Shoppinit & all, finally I got some news.
I took the car to my tuner for further testing, and here are the plots:
So in summary:
1/ Half the turbo boost between actual & specified. This is a MAJOR change as this wasn't showing before my vacations, as if the failure was almost there but not there yet.
2/ lambdas show excellent combustion on both banks
3/ Discrepancies between MAFs have never been as high: at idle I now get almost zero (yes zero) air measured through the left air intake.
My take:
- A big massive air leak on the left side (I know Shopp, you mentionned a thousand times I need to do a pressure test
)
- or Broken turbo
What the wise men say?
I took the car to my tuner for further testing, and here are the plots:
So in summary:
1/ Half the turbo boost between actual & specified. This is a MAJOR change as this wasn't showing before my vacations, as if the failure was almost there but not there yet.
2/ lambdas show excellent combustion on both banks
3/ Discrepancies between MAFs have never been as high: at idle I now get almost zero (yes zero) air measured through the left air intake.
My take:
- A big massive air leak on the left side (I know Shopp, you mentionned a thousand times I need to do a pressure test
)- or Broken turbo
What the wise men say?
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap
Re: Fuel Pumps
Feels like it could be the exhaust manifold that is breaking up and killing the turbo. Hope I’m wrong.
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."
///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."
Re: Fuel Pumps
Either way, it’s starting to seem a lot like a turbo failure.
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."
///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."
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