BCY cranking - non start 😭

4.2 V8 40v biturbo - 450 bhp
4.2 V8 40v biturbo - 480 bhp (plus)
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AshD2S8
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BCY cranking - non start 😭

Post by AshD2S8 » Sun Mar 06, 2022 5:42 pm

Does anyone know what crank position sensor RPM speed should read on cranking? I.E injectors unplugged, non start up?

Having issues, manual swapped C5 RS6 - non start after conversion into a D2 S8, wiring is paired and triple checked, couple of faults, G40& G163 implausible signal after extended cranking (longer that 6/7 seconds)

Does not fire up, cranks over, has spark, coils are working, injectors are flowing, cam position sensors working as they should and scope showing what they should be reading, IMMO is turned off, timing is correct, crank sensor intermediate loom as slightly damaged, swapped out for a good one, tried different positions of crank sensor in and out.

Pulling my hair out now, anyone have any ideas?
Last edited by AshD2S8 on Sun Mar 06, 2022 5:51 pm, edited 1 time in total.

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Shoppinit
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Re: BCY cranking - non start 😭

Post by Shoppinit » Sun Mar 06, 2022 5:50 pm

It does sound a lot like a problem with the crank position sensing.

Or maybe a massive timing problem. Is the flywheel position correct wrt TDC?

Have you tried unplugging the cam position sensors to see if that makes a difference?

Have you seen this engine running?
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."

AshD2S8
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Re: BCY cranking - non start 😭

Post by AshD2S8 » Sun Mar 06, 2022 6:03 pm

That’s the only thing I can put it down to to be honest,

Timing is 100% correct, checked and rechecked, all audi parts fitted when engine was stripped, new tensioners chains, belts, hydraulic tensioners blah blah.

Engine did run before removal from C5 albeit a few issues but all parts replaced prior to refit.

I have tried removal of the cam sensor plugs, most Vag engines will run off crank alone if cam unplugged but should throw a fault, the only faults I get when removing the cam sensor plugs is data bus missing messages from the power train control module.

Not sure about the flywheel position for tdc, wasn’t anything in the instruction from ttv to set anything to tdc etc, unless you mean the pick up the on flywheel sorry to tell it it’s on tdc.

It was so long ago I fitted the flywheel, tried getting a scope in the gearbox earlier but couldn’t see a huge amount.

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Shoppinit
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Re: BCY cranking - non start 😭

Post by Shoppinit » Sun Mar 06, 2022 6:10 pm

I was going to suggest getting a scope on the crank sensor to see what was coming back. Shouldn't be too difficult to get to the contacts and see what the signal looks like.

Having said that, if you're getting a spark then the ECU must think it's firing the coil pack at the right time, so it must be getting a crank signal, just not at the right time. Or at least, not consistently.

Concerning the flywheel position, my thinking was that if the flywheel can go back on in several different positions, like if there's no locating pin, then that could cause the timing to be completely off. Where did the flywheel come from? Has the engine run with it on before?

Stupid question, is the starter turning the engine in the right direction?
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."

AshD2S8
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Re: BCY cranking - non start 😭

Post by AshD2S8 » Sun Mar 06, 2022 6:23 pm

AC voltage test on cranking show 0.5v which is next to nothing, only issue is the only thing I had to reference it to on a test plan was a 1.8t 20v, I would of thought same era it would be roughly the same but on idle that should be seeing 7v, so approx 800rpm @ 7v .
I’m reading 0.5v at 160 rpm.

Should also see a wave pattern of 15v at max rpm, on cranking im getting a wave form of 3v + or - .

Resistance check read 0.89kohms between pin 2&3 (signal wires) 500ohms should be max, hence the change of intermediate loom and G28.

92% sure the flywheel on fitted one way round on the bolt holes but I could be completely wrong in that, it’s been a long time 😂

Starter is also okay 😊

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Shoppinit
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Re: BCY cranking - non start 😭

Post by Shoppinit » Sun Mar 06, 2022 7:23 pm

You'd need a proper scope to get a meaningful reading of the voltage. If you're using a multimeter on AC then you're not likely to see representative values.
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."

AshD2S8
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Re: BCY cranking - non start 😭

Post by AshD2S8 » Sun Mar 06, 2022 8:16 pm

I can scope it with my diagnostics but il need a reference to compare it to, it doesn’t give me expected results for a BCY unfortunately.

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Re: BCY cranking - non start 😭

Post by bilko1 » Mon Mar 07, 2022 10:43 am

I'm sure Bowers had a similar problem when he did the manual conversion had to use a different CPS due to the different flywheel. viewtopic.php?f=2&t=133606&hilit=manual last post on first page
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AshD2S8
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Re: BCY cranking - non start 😭

Post by AshD2S8 » Mon Mar 07, 2022 12:29 pm

Me and bowers are very good friends, he’s doing all his stuff in my workshop, even used his crank sensor and wiring adapter to check but still nothing, going to have to remove my CPS and check the trigger on the flywheel location

AshD2S8
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Re: BCY cranking - non start 😭

Post by AshD2S8 » Mon Mar 07, 2022 1:26 pm

Just checked the flywheel trigger location through CPS hole, Vs the factory location in the flex plate and it is off! Good ole TTV 🙄

Top image is my crank pulley with the trigger in the cps hole, bottom image is my spare bcy with the flex plate trigger in roughly the right place give it take 1/2 tooth (haven’t gotten a box on it)
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Shoppinit
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Re: BCY cranking - non start 😭

Post by Shoppinit » Mon Mar 07, 2022 1:30 pm

You can stop tearing your hair out now. Yeah, that was never going to fire up.
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."

AshD2S8
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Re: BCY cranking - non start 😭

Post by AshD2S8 » Mon Mar 07, 2022 8:04 pm

Waiting to hear back from TTV now, good times, week wasted working on my car instead of customers cars. Loss of earnings for an entire week for no reason at all 🙃

Thanks for all your help 🙏🏼

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