S8 d3 v10 2007 engine torque settings

[audis8tui]

Originally Posted by Mechcanico Lee

Good guess Del but in most cases they don't run that close normally , the clue was in my first post " has it ingested water "
Even though this may not be the issue with this engine the symptom of nibbled skirt is the same .......

Bent con rod ?? If it was stolen and had the death ragged out of it , but in most cases the rev limiter will stop that sort of damage .

So a bent rod will not reach top dead it will be short of reaching deck height , but on the downward stroke the shortened rod pulls the piston further down the bore and in some cases clipping the skirt on the crank counter weight .

It may not be this but you have to rule all of the causes

Audis8tui have you turned engine over with heads off to see if that piston in question falls short of the deck height .

That I haven't tried, my new piston will be here Wednesday and I will check that. The con rod looks good with no damage to bearing.
I do have another issue with the car which I was going to deal with after the engine is fitted, there is a misfire on start up for 4 mins on the same bank, I forget the code but it tells me low fuel pressure on all 5 cylinders.
After 4 mins all good and I can leave the car all day and it doesn't return but left over night its back.

[Delboy]

Originally Posted by audis8tui

That I haven't tried, my new piston will be here Wednesday and I will check that. The con rod looks good with no damage to bearing.
I do have another issue with the car which I was going to deal with after the engine is fitted, there is a misfire on start up for 4 mins on the same bank, I forget the code but it tells me low fuel pressure on all 5 cylinders.
After 4 mins all good and I can leave the car all day and it doesn't return but left over night its back.

Leak on the HP fuel pump on that bank???

[audis8tui]

If it was a fuel leak would it not leak all the time, I have no smell of fuel either. I think its more electrical, sensor or even ecu.

[Mechcanico Lee]

Mmmm ,Injector leaking badly on the damaged piston cylinder pulling the rail pressure down on that bank , cold start missfire is cylinder flooded with fuel and taking time to clear it , any signs of bore wash on that cylinder ( more wear )

[audis8tui]

Good thought, not thought of that. would it take that long though to burn it off.
All the bores look and feel identically smooth, all piston crowns look the same also.
The head gasket was also good and the valves still clean after the de coke I did 3 months ago.
If I start the car in the morning and leave to tick over for 4 mins (which I know isn't good for the engine) turn the engine off and then restart all is good.

If I start the car and drive off it can be 5 mins before all 10 are firing and with slow moving traffic the only way I know all is working is the management light stops flashing

[Mechcanico Lee]

No I wouldn't think it would take that long really , could you look at injector corrections with vcds .
The high pressure petrol pumps , do they suffer like the vauxhalls with the same systems , where they break up internally and send metal debris down to injectors...... I've never under stood how you can lubricate high pressure petrol pumps with petrol .... there's not much lubrication property's in petrol unlike a diesel high pressure pump .

I can understand the injectors or pump causing missfires and so on , but what has broke that skirt , you say it come on after the car was stolen , wonder if it just got a ragging from cold before its expanded properly and it's just rattled in the bore and broke it
Not sure ....!interesting one this

[Delboy]

If one of the injectors was leaking badly could there be enough fuel to create hydraulic lock on the cylinder to bend the rod while the engine was starting?

I guess that will be proven when new piston arrives.

[tonupkid]

Fascinating thread. Thanks
I've always been able to figure why, when I've been piston broke. Hope to hear an explanation for this one sometime.
Perhaps its down to a faulty/damaged piston fitted in the first place, Maybe there's a lot of V10's with the odd piston skirt damaged, and we're unaware of it and the clicking noise was caused by something else.

[tc4332]

Note that parts of the piston were found in the sump that fitted the damaged piston

[Mechcanico Lee]

Pistonbroke .....yeah been there hehe

Interesting one this , if it's not a bent rod or it's not running close to the crank counter weight in any way , my next best surmise would be an over revving from cold , if the cars been stolen and in a chase this could be likely and yes it could of been a manufacturing defect and it only showed its face on the one piston .....it's hard to say , we could guess at a lot of things ..

You say it misses from cold , and the codes to do with low fuel pressure on that bank ..... would you say it's like one cylinder down or more or a general unevenness to it .

Has anyone had a Diesel engine run away with its self due to say a turbo failure or sump overffull of oil ..... I've had it once on a td6 Range Rover .... it's pretty scary ...... Billowing smoke and screaming it's nuts off till it throws a rod out , makes a reet mess ......... where am I going with this .......

So in some cases with a major over Rev the high pressure diesel pump breaks up ,the case hardening comes off the rotor and metal debris is scattered around the system .....where does the metal end up ....... yes ,in the injectors , so you end up with low pressure codes due to the back spills dumping it out .... high pressure fuel systems will not tolerate metal debris what so ever , the fuel system is as good as finished , contamination in pump , injectors , fuel rails , swirl chamber in tank , metal debris all in bottom of tank due to fuel returning all the debris back there .

Could this be the reason our v10 is giving codes for one bank for low fuel pressure , if a diesel pump breaks up and that is lubricated with oil , I would say for sure a high pressure petrol pump will break up .
Perhaps it's still able to deliver fuel but not up to spec , perhaps after the car has run for 5 mins or so the cylinder balancing and contribution is ramping the pressure and duration on that bank to get it to contribute to get engine smoothness.

On the bank that has low pressure.....the high pressure pump does it have a return pipe that has a banjo bolt with a basket filter in the banjo , or any return line banjo bolts for that matter , take them out and look for metal debris .

If you need the injectors testing I have a man .....he is Martin Wainwright from Wainwright Bros. look him up on YouTube .... proper professional and will inspect the nozzles and pintles under a microscope to look for metal particles

Lots of theory's and maybes , but to do all the work you already have done there , you have got to get it checked out ..... massive waste to put it all back and it not be right .

Respect to you for taking a big job on like that , most garages just don't want this type of work ....just to long winded and if one small thing is over looked you would be pulling it all back out again .

Lee