Starts up then dies!

4.2 V8 40v biturbo - 450 bhp
4.2 V8 40v biturbo - 480 bhp (plus)
M4TTY_D
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Starts up then dies!

Post by M4TTY_D » Sun Jan 29, 2017 9:14 pm

For the past week ive been going out to the rs6 every other day to find it dies as soon as i start it up when the revs drop back down. Its had 4 fuel trim faults and a random multiple misfire for a couple of weeks (no eml) but it does run rough when i start it from cold and hold revs on. As soon as its warm it runs sweet with no problems and ticks over lovely..

Any ideas?

Ajc
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Re: Starts up then dies!

Post by Ajc » Sun Jan 29, 2017 10:39 pm

I would be starting with sensors , first I'd be looking at the engine coolant temp sensor and checking it hadn't sh*t the bed .
Cheers Al

04 c5 rs6 , Ebony Black, Bare shell repaint , Milltek's, PSS9's,Hotchkis Arb's,Gutted precats, hybrid turbos, Bosch 044 ,And an annoying EML light

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Shoppinit
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Re: Starts up then dies!

Post by Shoppinit » Mon Jan 30, 2017 11:16 am

Did you change the plugs and coil packs like you said you were going to?

Post up your fault codes.
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."

M4TTY_D
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Re: Starts up then dies!

Post by M4TTY_D » Mon Jan 30, 2017 11:40 am

The fault codes are as follows;

17538/P1130 - Fuel Trim; Bank 2 (Mult): System too Lean
17546/P1138 - Fuel Trim: Bank 2 (Add): System too Lean
17544/P1136/004406 - Fuel Trim: Bank 1 (Add): System too Lean
16814/P0430/001072 - Catalyst System; Bank 2: Efficiency Below Threshold
16684/P0300/000768 - Random/Multiple Cylinder Misfire Detected
16690/P0306/000774 - Cylinder 6 Misfire Detected
16691/P0307/000775 - Cylinder 7 Misfire Detected

Prior to getting these codes i also had the fuel trim bank 1 (mult) system too lean code and misfires on cylinders 4-8.
I cleared them and these come straight back up although i dont normally get the catalyst fault.

My original thought was maybe an air leak but as said once its been run for 10 minutes it ticks over lovely if it was an airleak wouldn't the constant rough idle stay there?

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Shoppinit
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Re: Starts up then dies!

Post by Shoppinit » Mon Jan 30, 2017 12:04 pm

Definitely sound like an air leak. It's much worse at idle, but can smooth out when the engine is warmed up and needs less fuel - the trim can just about balance it out at warm idle.

Have a look in measuring block 32 and tell us what the 4 values are. Don't clear your codes before doing this.
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."

Ajc
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Re: Starts up then dies!

Post by Ajc » Mon Jan 30, 2017 12:15 pm

Surely with a air leak the idle would stay high due to the extra unregulated air going in ? .
Cheers Al

04 c5 rs6 , Ebony Black, Bare shell repaint , Milltek's, PSS9's,Hotchkis Arb's,Gutted precats, hybrid turbos, Bosch 044 ,And an annoying EML light

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Shoppinit
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Re: Starts up then dies!

Post by Shoppinit » Mon Jan 30, 2017 12:28 pm

It doesn't. The engine reduces the fuel to keep the idle down.
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."

M4TTY_D
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Re: Starts up then dies!

Post by M4TTY_D » Mon Jan 30, 2017 12:33 pm

Just come out and started the car up and its idling smooth. Seems to be a lot worse at really cold temps?

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Shoppinit
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Re: Starts up then dies!

Post by Shoppinit » Mon Jan 30, 2017 12:38 pm

Yes, that's generally when idle problems are worse.
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."

Ajc
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Re: Starts up then dies!

Post by Ajc » Mon Jan 30, 2017 1:56 pm

Shoppinit wrote:It doesn't. The engine reduces the fuel to keep the idle down.
So it uses fuel ratio to control idle speed rather than a traditional air bypass idle valve ?
Cheers Al

04 c5 rs6 , Ebony Black, Bare shell repaint , Milltek's, PSS9's,Hotchkis Arb's,Gutted precats, hybrid turbos, Bosch 044 ,And an annoying EML light

srichards
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Re: Starts up then dies!

Post by srichards » Mon Jan 30, 2017 2:11 pm

The secondary air pump is also used for the first 10 minutes or so. Is that mapped out or removed? If not then I'd unplug it and see if it behaves differently.

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Shoppinit
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Re: Starts up then dies!

Post by Shoppinit » Mon Jan 30, 2017 2:14 pm

Ajc wrote:
Shoppinit wrote:It doesn't. The engine reduces the fuel to keep the idle down.
So it uses fuel ratio to control idle speed rather than a traditional air bypass idle valve ?
Yes. No idle valve.
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."

M4TTY_D
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Re: Starts up then dies!

Post by M4TTY_D » Mon Jan 30, 2017 2:22 pm

Just come out and started the car up and its idling smooth. Seems to be a lot worse at really cold temps?

Ajc
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Re: Starts up then dies!

Post by Ajc » Mon Jan 30, 2017 2:30 pm

Shoppinit wrote:
Ajc wrote:
Shoppinit wrote:It doesn't. The engine reduces the fuel to keep the idle down.
So it uses fuel ratio to control idle speed rather than a traditional air bypass idle valve ?
Yes. No idle valve.
I'm obviously more old school than even I thought :bash: .
Cheers Al

04 c5 rs6 , Ebony Black, Bare shell repaint , Milltek's, PSS9's,Hotchkis Arb's,Gutted precats, hybrid turbos, Bosch 044 ,And an annoying EML light

Ajc
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Re: Starts up then dies!

Post by Ajc » Mon Jan 30, 2017 2:32 pm

crazymatty125 wrote:Just come out and started the car up and its idling smooth. Seems to be a lot worse at really cold temps?
have you checked the coolant temp sensor ? if its reading incorrectly then obviously fueling will be effected. Are the maf's seated correctly?
Cheers Al

04 c5 rs6 , Ebony Black, Bare shell repaint , Milltek's, PSS9's,Hotchkis Arb's,Gutted precats, hybrid turbos, Bosch 044 ,And an annoying EML light

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