997 DFI valves coking up / injector fault .

Cheers Phil .

I'm sure every Indy does the same thing when they perceive a problem that will need addressing in the future .

For us we are at the beginning really .. we have already bought a far more expensive walnut cleaning tool to try out as this obviously needs to be done in situ ... ill post some images next week of it .

We might need some guinea pigs in our area though .. need to chat to the Boss about that lol .

It has possibilities on Diesels as well .. not that i'm a fan of them .. sorry but im not .

Our basic thought atm .. pre demoing the machines is a walnut clean then followed by a machine clean as we just don't feel a machine clean will be as effective .. but we will see after the demo and we strip the car apart to inspect the results

Work in progress and i will post the results as i get them !

deMort said:

Cheers Phil .

I'm sure every Indy does the same thing when they perceive a problem that will need addressing in the future .

For us we are at the beginning really .. we have already bought a far more expensive walnut cleaning tool to try out as this obviously needs to be done in situ ... ill post some images next week of it .

We might need some guinea pigs in our area though .. need to chat to the Boss about that lol .

It has possibilities on Diesels as well .. not that i'm a fan of them .. sorry but im not .

Our basic thought atm .. pre demoing the machines is a walnut clean then followed by a machine clean as we just don't feel a machine clean will be as effective .. but we will see after the demo and we strip the car apart to inspect the results

Work in progress and i will post the results as i get them !

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Ah I can see a 911uk bacon butty opportunity looming :grin: :grin: :grin:

:floor:

I very much doubt there's anything to clean on your car !

We will need a 60 - 70 K car i expect that hasn't been touched .. but that's for the Boss to sort out .. i'm just a Grunt

Got to admit .. you leaving our place at the open day still makes me smile .. as does the sound of your car .. awesome is all i can say .. and again ..

What about dry ice blasting would that work?

deMort said:

:floor:

I very much doubt there's anything to clean on your car !

We will need a 60 - 70 K car i expect that hasn't been touched .. but that's for the Boss to sort out .. i'm just a Grunt

Got to admit .. you leaving our place at the open day still makes me smile .. as does the sound of your car .. awesome is all i can say .. and again ..

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That was a great get together mate. :thumb: :thumb: :thumb: :floor: I agree my rebuild still only has 5k miles on it so maybe a while before it needs a clean . :grin: :thumb:

My goodness Ian, what a gent you are sir. Please feel no pressure to respond to any of my rambles, I am just trying to keep the old grey matter ticking over by remembering past experiences and trying to understand better the realities of owning and running a modern Porsche, the insight you provide is priceless, thank you so much. :worship:

Luddite said:

My goodness Ian, what a gent you are sir. Please feel no pressure to respond to any of my rambles, I am just trying to keep the old grey matter ticking over by remembering past experiences and trying to understand better the realities of owning and running a modern Porsche, the insight you provide is priceless, thank you so much. :worship:

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You do tend to go in depth when posting .. i wish i had more time to answer and debate things with you ... unfortunately that's not the case but i do always read what you post and pick what i can to answer .

Trust me .. i Do read what you post ! :thumb:

Keep it up !

Just a humble mechanic here doing his best .

MR997 said:

What about dry ice blasting would that work?

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Yup .. but it would be the same as walnut ... the trouble we have is the amount of work needed to strip down the parts to be able to do this .. we are looking for a more cost effective solution atm .. hence seeing what the machines can do .

MattyR said:

Wasn't the B7 RS4 renowned for this?

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It was. I stripped my B7 down and walnut shell blasted it as demort has with this 911. The difference was phenomenal! Though access to a B7 is considerably easier than a 911. I look in my 911 and just close it again :worship:

WOW the difference in those pics is just huge. amazing work. the coked up inlets and valves look in a right state and no wonder it was running badly. looks like a great job done

they did change the 997.2 engine to a different design and to DFI...sounds like it comes with its own challenges as age and mileage is starting to show.

am guessing that doing this walnut cleaning is a lot cheaper than having to do a 997.1 engine that has been scored and needs new liners?

am thinking about going 997.2 and this is an eye opener and thanks

Ian I do not come here to "debate" I leave that to the politicians....look where that gets us..!!! (-:

I come here to learn, and boy have I learned a lot...THANKS... Trying to remember any or all of it is the hard part.. Duh!

Seems obvious that the inefficiency of the AOS system is the issue with the DI engines...Quite where Porsche or anyone else might go with that who knows..?

Seems taking a step back might be the next step forward... if you get what I mean... ? (-:

IF the inlet tract and valves HAVE to be de-coked at circa 70k miles to overcome a considerable drop of in efficiency (?)... Forgive me but that does not seem to be...err...terribly efficient..?

The idea that spark plug threads are required to project into the combustion chamber for some reason seems to hint at cost cutting in the design process...?

So the exposed threads pick up carbon, which causes problems when trying to remove the spark plugs..?

How so, would seem to be the next question..? On trying to remove the plugs does the carbon jamb in the cylinder head threads risking damage to them as opposed to the harder material of the spark plug threads..?

Is the process for removal one of working the plugs back and forward to try to release the carbon from the exposed threads allowing the spark plug to be removed and the freed off carbon to end up where ..???

I guess my simplistic thought processes might lead me to add a couple of extra compression washers to the spark plug to ensure that the threads did not end up in the combustion chamber to collect carbon deposits...

Another rather obvious thought might be that perhaps Porsche engineers decided for that the best performance outcomes the PRECISE point at which the spark MUST be generated is in the present position in the combustion chamber...? IF that were the case, the exposed threads that seem to hold carbon so well, could be removed from the spark plug body and that area of the spark plug body smoothed off, similar to diesel pre-heat plugs..?

My thinking on the risks relative to the disruption to the engine ancillaries and bank balance involved in the de-coke process was more related to items that may be broken or damaged to get at the inlet tract, the stuck injector being one example, but it seems to me that water cooled Porsches have rather a lot of gubbins that requires to be disturbed, unbolted, unplugged and removed, compared to simpler designs of the past..Shrug..! Jeez even one electrical connection on a sensor disturbed, can cause issues, let alone a broken/corroded bolt or stud....?

All that aside... on using compression via a slow turn on the engine.... As you guys know I have never put hands on a water cooled 911, but I have used pressure to remove and replace valve springs on a Porsche engine to avoid removing the head, I think I explained the process some time back on this forum.. Combine that with an injector imitating a missile mentioned previously, and it seems possible that a bit of thinking out of the box might be worth a try...ONLY if the forces in play are WELL understood...

Compressed air can be used to start diesel engines the size of a house, so spitting out an injector seems a possibility, as to how that process might be controlled.... there may be ways and means worth trying...? (-:

Ian, if you are reading this, I am flattered, please take no time to reply to my innate ramblings.... I am as ever just thinking in type, in an attempt to keep my brain from seizing up.. ld:

Interesting thread!

My 997.2 is now over 72k. Bought it at 20k 6.5 years ago, and having run another car for most of that period, have now made my 911 my daily, so the mileage is piling on.

Haven't noticed any loss of power or uneven running yet - fingers crossed.

DeMort - where is your Indy?

AOS is probably the best that can be made so its a case of live with it .. a small amount of oil is never going to be an issue .. erm .. well in this case and long term then perhaps it is ! it's still Porsche design though so it's what we have regardless .

Change debate to discuss .. just a mechanic here so i don't always get the correct wording

de coke is what we used to do back in the day .. that was down to poor fuel and oil .. this is a new design that has designed the same fault into it ..

What we are trying to find out is what if any difference it will make and what we can do about it ... no facts as of yet .

The spark plugs are in that position for a reason .. i can only guess at that so we just deal with the end result ..

That being said these have been a problem to remove from 4 years old .. Boxster and 997 G2 ( DFI ) .. we undo .. do up .. undo etc to remove .. i've had one at 6 years ( missed plug change ) that i couldn't get them out at all .. did in the end but that's on another thread how i did it .

The cyls will have a certain amount of carbon in them .. a tiny amount from the plug threads makes no difference .. it will just get blown out with the exhaust .

Carbon to the point of a build up jamming a piston , snapping a chain .. yup i've seen it once .. not on a DFI car though .. G1 cayman .. never did get to the bottom of the reason for that but it was certainly due to an excessive amount of carbon build up on the piston crown .

Compression to remove it .. we considered all options and an engine drop was the best in the circumstances .. a long answer to go into the reason though and time is limited so forgive me there for not explaining it

I hoped to raise questions for others to consider Iain, and not to elicit answers directly from you...

I will cease and desist on this topic.. BTW there is no such person as JUST a mechanic...!!!

As well as being a highly skilled mechanic/technician you are also a teacher with rather large pupil numbers in your cyber class... :worship:

lol .. bless you .. but you can ask any questions you like and i'll do my best .. time is the enemy here though .. never enough of it .. and with that i bid you goodnight !!!