Fuel Pumps

4.2 V8 40v biturbo - 450 bhp
4.2 V8 40v biturbo - 480 bhp (plus)
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Shoppinit
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Re: Fuel Pumps

Post by Shoppinit » Tue Apr 09, 2019 9:52 am

The turbo doesn't care where the air it's sucking in is coming from, or whether it's metered or not. The air could be leaking in from anywhere upstream of the turbo.

Have you also checked your DVs? If one of them has perished it could be sending air from one bank to the other. Probably not at idle though.
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."

Classik
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Re: Fuel Pumps

Post by Classik » Tue Apr 09, 2019 11:27 am

Shoppinit wrote:
Tue Apr 09, 2019 9:52 am
The turbo doesn't care where the air it's sucking in is coming from, or whether it's metered or not. The air could be leaking in from anywhere upstream of the turbo.
Makes sense of course.. :oops:
Shoppinit wrote:
Tue Apr 09, 2019 9:52 am
Have you also checked your DVs? If one of them has perished it could be sending air from one bank to the other. Probably not at idle though.
They are new ones (OEM), but I could swap them if required.

Now back to my tests this morning:
I did install the MAFs WITHOUT the airbox, so I'm 100% sure they are correctly seated.
- During the first minutes or so, I was very happy as the MAF were giving almost identical values, I mean very very close far below the 10% margin suggested above 8)
- However, as soon as the engine was hot enough (Coolant >= 80°C & oil >60°C), the discrepancies between L&R banks re-appeared :evil:

This is bad news indeed, but I try to keep a positive attitude and try to avoid burning the car today.. :FIREdevil:

So If I'm not mistaken, down the line we have :

1/ Those boost hoses from the intake to the turbo. Please give me some good news: can those (and their clamps) be checked/changed/tighten without an engine pull?
2/ The turbos: can they have an air leak? I guess a log showing actual and target pressures should show a problem if any, right?
3/ The Wagner intercoolers : brand new with their silicon hoses, but checking the clamps can't do no harms
4/ Intake manifold: I already tried to identify any air leak by spreading vaporized soapy water on the sides edges, where the manifold meets the head cover, but no bubbles nor RPM changes. Not easy check anything there though...

Anything I missed? I suppose option 1/ is my main option?
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

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Re: Fuel Pumps

Post by Shoppinit » Tue Apr 09, 2019 11:38 am

Have you swapped the MAFs left to right to compare?
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."

Classik
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Re: Fuel Pumps

Post by Classik » Tue Apr 09, 2019 11:46 am

I've already done that when they were attached to the airbox, but no change : bank 2 measures always higher when the engine is hot. Shall I swap them 'naked' (without the airbox)?
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

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Re: Fuel Pumps

Post by Shoppinit » Tue Apr 09, 2019 11:51 am

If it's easy. That way you definitely eliminate the MAfs as the cause.

Can you make the MAF plugs reach the 'wrong' MAF? Could be a secondary test to eliminate wiring / ECU issue.
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."

Classik
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Re: Fuel Pumps

Post by Classik » Tue Apr 09, 2019 11:57 am

The connectors are quite short, but as the MAFs can freely rotate I can indeed try that. What I find really strange is the fact that the results differ a lot if the engine is cold or hot.. Anyway I'll try and report
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

Classik
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Re: Fuel Pumps

Post by Classik » Tue Apr 09, 2019 12:31 pm

Ok, I've swapped the naked MAFs : same results, so the MAFs are working fine. However there's no way I can exchange the connectors without some cable extension. I suppose I can order one (actually 2) on the net..

EDIT: I suppose one of those should fit:

http://ec91138023.sell.everychina.com/p ... er-12.html

I just need to find a dealer who's got them closer than in China...
Last edited by Classik on Tue Apr 09, 2019 12:44 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

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Re: Fuel Pumps

Post by Shoppinit » Tue Apr 09, 2019 12:43 pm

It's pretty unlikely that it's a wiring or ECU problem anyway, but it would have been good to eliminate it if the cables had reached.
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."

Classik
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Re: Fuel Pumps

Post by Classik » Tue Apr 09, 2019 12:51 pm

Sure... And in the same spirit of leaving no stones unturned, do you believe a clogged fuel rail (Bank 1 side) or injector could lead to such discrepancies?
And do you know if our #1 suspect (boost hoses) can be accessed without pulling out the engine?

Many questions I know, many thanks for your time!! :thumbs:
Last edited by Classik on Thu Apr 11, 2019 6:26 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

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Re: Fuel Pumps

Post by Shoppinit » Tue Apr 09, 2019 12:55 pm

No, because your MAF reading is not dependent to your fuel supply. The reading is a measurement of a physical drawing of air through the MAF by the engine. Either the vacuum from the pistons descending or the the turbo sucking air in.

So either you've got a leak that is letting air into the system on one bank only (that limits the number of places somewhat, at least) or there is something that is causing an imbalance in the pressures. You can get that if you get a blocked turbo and the pressure from the other turbo forces its way back up and out through the MAF.
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."

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Shoppinit
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Re: Fuel Pumps

Post by Shoppinit » Tue Apr 09, 2019 12:56 pm

I don't know about the accessibility of the hoses. Given where they are, it won't be fun trying to get at them.

But a simple boost leak test might find your leak. Have you tried one? Block one inlet off and pressurise through the other on and see if it holds pressure.
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."

Classik
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Re: Fuel Pumps

Post by Classik » Tue Apr 09, 2019 1:20 pm

Shoppinit wrote:
Tue Apr 09, 2019 12:56 pm
I don't know about the accessibility of the hoses. Given where they are, it won't be fun trying to get at them.
Given my (bad) luck, I'm not surprised..
Shoppinit wrote:
Tue Apr 09, 2019 12:56 pm
But a simple boost leak test might find your leak. Have you tried one? Block one inlet off and pressurise through the other on and see if it holds pressure.
I haven't done a single boost leak test in my life, but always happy to learn. When you say inlet, you mean where the MAFs go, right? So I need to find the correct adaptor to block one side and push pressure through the other side.
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

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Re: Fuel Pumps

Post by Shoppinit » Tue Apr 09, 2019 1:41 pm

Yes. Have a search on here. I think nobby used a Peugeot CV joint to block his inlet. You shouldn't have difficultly finding one of those where you are. :)

There might even be a kit. There was a thread a couple of months ago where someone said they bought one to do a leak test. And linked to it, IIRC.
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."

User avatar
Shoppinit
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Posts: 20318
Joined: Wed Dec 31, 2008 6:24 pm

Re: Fuel Pumps

Post by Shoppinit » Tue Apr 09, 2019 1:43 pm

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."

Classik
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Posts: 702
Joined: Sun Jul 15, 2018 1:13 pm
Location: Paris

Re: Fuel Pumps

Post by Classik » Tue Apr 09, 2019 2:24 pm

Shoppinit wrote:
Tue Apr 09, 2019 1:41 pm
Yes. Have a search on here. I think nobby used a Peugeot CV joint to block his inlet. You shouldn't have difficultly finding one of those where you are. :)

There might even be a kit. There was a thread a couple of months ago where someone said they bought one to do a leak test. And linked to it, IIRC.
haha, yes, if anyone needs parts for their Peugeot I guess I can help ;)

Many thanks for the link!
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

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