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whats the best test to run to check for overfueling? oil analysis a good way to look into it?
Oil analysis for one. We're adding an extra test to the Speed Diagnostix program to be able to give much more accurate fuel dilution data. We're hoping the equipment will be up and running in the next 90 days. Will raise the cost $3-4 per test, but I think it's worth knowing as I believe over-fueling is one of the biggest issues we are facing now with these engines as injectors fail and plastics start to crack, causing vacuum leaks.
Having access to a Durametric to check fuel trim values at every service and monitor those changes, if any are present.
Another quick and easy test is to check the crankcase manometer reading when the engine is hot. That's a good indicator of engine health as it measures how well the cylinders are sealing up.
Smoke testing the engine is another great way to determine if there are any vacuum leaks and it's common to find some that will affect enrichment as shown in the Durametric, but not throw a CEL, as the car will just add more fuel through adaptation.
Testing and cleaning injectors used to be standard at time of rebuild. We're mandating new ones as we can't trust rebuilt ones after seeing them fail on fresh rebuilds repeatedly.
I know some will think that this is overkill, but I'm thinking that cars that are 8-10 years old or older should have new injectors fitted with such a large increase in 987.1 and 997.1 models with scoring popping up, and most recently 997.2s. I don't know enough about the DFI injectors to know how they fail or how sensitive they are to contamination in the fuel, ethanol, or age/time in service, or the fact that most of these cars don't have fuel filters other than the in tank filter that is integral to the fuel pump.
Likewise, I just got an email this morning from S. Korea with the same scoring in their 997.2 3.8 as the OPer's:
See photo above. How can the piston side skirt, which has a much smaller diameter than the rings, be scored that way along the vertical direction with that level of uniformity? It is hard to understand that that is the result of friction contact with the cylinder wall.
See photo above. How can the piston side skirt, which has a much smaller diameter than the rings, be scored that way along the vertical direction with that level of uniformity? It is hard to understand that that is the result of friction contact with the cylinder wall.
I d' like to know too. Especially the scoring area on the skirt right below the rings.
Damage to the cylinder wall is being transferred to the piston as the piston travels through the damaged area of the cylinder. Piston rock may help accelerate this process.
See photo above. How can the piston side skirt, which has a much smaller diameter than the rings, be scored that way along the vertical direction with that level of uniformity? It is hard to understand that that is the result of friction contact with the cylinder wall.
Notice the oil passages through the oil ring groove are directly in line with this.. They always are with DFI engines, and this failure. The skirt of the piston is smaller in these areas.
It took us a good bit of research to figure out the common denominator here... This is a constant with other DFI engines with cylinder issues too, outside of Porsche. We altered our pistons to alleviate this scenario as of late. No, its not contamination. More later, when I have time to write a dissertation... Nah, I’ll just do a video to explain it.
Oil analysis for one. We're adding an extra test to the Speed Diagnostix program to be able to give much more accurate fuel dilution data. We're hoping the equipment will be up and running in the next 90 days. Will raise the cost $3-4 per test, but I think it's worth knowing as I believe over-fueling is one of the biggest issues we are facing now with these engines as injectors fail and plastics start to crack, causing vacuum leaks.
Having access to a Durametric to check fuel trim values at every service and monitor those changes, if any are present.
Another quick and easy test is to check the crankcase manometer reading when the engine is hot. That's a good indicator of engine health as it measures how well the cylinders are sealing up.
Smoke testing the engine is another great way to determine if there are any vacuum leaks and it's common to find some that will affect enrichment as shown in the Durametric, but not throw a CEL, as the car will just add more fuel through adaptation.
Testing and cleaning injectors used to be standard at time of rebuild. We're mandating new ones as we can't trust rebuilt ones after seeing them fail on fresh rebuilds repeatedly.
I know some will think that this is overkill, but I'm thinking that cars that are 8-10 years old or older should have new injectors fitted with such a large increase in 987.1 and 997.1 models with scoring popping up, and most recently 997.2s. I don't know enough about the DFI injectors to know how they fail or how sensitive they are to contamination in the fuel, ethanol, or age/time in service, or the fact that most of these cars don't have fuel filters other than the in tank filter that is integral to the fuel pump.
Likewise, I just got an email this morning from S. Korea with the same scoring in their 997.2 3.8 as the OPer's:
Charles, thanks for the response. When you start running your tests with the Speed Diagnostix program, I’m interested in sending mine in for an analysis. Please post when that’s up and ready. Thank you for all of your advice and help.
Oil analysis for one. We're adding an extra test to the Speed Diagnostix program to be able to give much more accurate fuel dilution data. We're hoping the equipment will be up and running in the next 90 days. Will raise the cost $3-4 per test, but I think it's worth knowing as I believe over-fueling is one of the biggest issues we are facing now with these engines as injectors fail and plastics start to crack, causing vacuum leaks.
Having access to a Durametric to check fuel trim values at every service and monitor those changes, if any are present.
Another quick and easy test is to check the crankcase manometer reading when the engine is hot. That's a good indicator of engine health as it measures how well the cylinders are sealing up.
Smoke testing the engine is another great way to determine if there are any vacuum leaks and it's common to find some that will affect enrichment as shown in the Durametric, but not throw a CEL, as the car will just add more fuel through adaptation.
Testing and cleaning injectors used to be standard at time of rebuild. We're mandating new ones as we can't trust rebuilt ones after seeing them fail on fresh rebuilds repeatedly.
I know some will think that this is overkill, but I'm thinking that cars that are 8-10 years old or older should have new injectors fitted with such a large increase in 987.1 and 997.1 models with scoring popping up, and most recently 997.2s. I don't know enough about the DFI injectors to know how they fail or how sensitive they are to contamination in the fuel, ethanol, or age/time in service, or the fact that most of these cars don't have fuel filters other than the in tank filter that is integral to the fuel pump.
Likewise, I just got an email this morning from S. Korea with the same scoring in their 997.2 3.8 as the OPer's:
I see that the beautiful oil squirter/cooler is directed to the underside of the piston top (like most engines), not the cylinder wall thrust side. Also looks like the piston coating has all been worn off the skirts, even in the unscored area.
Are the injectors for the 997.2 the ones that cost $300 each ($1800 for the set)? Is there a cheaper non-Porsche labeled alternative?
I wouldn't dare run non-OEM or genuine injectors.
I don't think there is an aftermarket high pressure DFI injector.
With Bosch, you need to make sure you verify they are indeed genuine as there are Chinese knock-offs. When you buy a new injector Bosch, there is a hologram on the box and a code to enter on the Bosch website to verify it's actually genuine.
I don't think there is an aftermarket high pressure DFI injector.
With Bosch, you need to make sure you verify they are indeed genuine as there are Chinese knock-offs. When you buy a new injector Bosch, there is a hologram on the box and a code to enter on the Bosch website to verify it's actually genuine.
Thanks for the reply and the heads up regarding the fake Bosch injectors Charles. No chance in hell that I would put aftermarket injectors either, but I was wondering if maybe the genuine Bosch injectors where available like the ones for the 997.1 on the Pelican Parts website which cost a fraction of the Porsche labeled ones.
Notice also that the most scoring is at the bottom of the cylinder (much lower than M96/7 scoring) and exactly in line with the part of the casting that forms the area to hold the main bearing shells and is the thick area that we found causes shrinkage - exactly as previously explained and described several weeks ago. notice also that the centre of the piston (where it is largest) has not scored - but the sides (where the piston is already smaller due to ovaility machined into it) has scored.
More on this later - just surprised those following this problem have not managed to link what we originally explained and the exact same physical evidence in this case?
Does the above photo of the scored 997.2 cylinder not finally settle the assertions that bore scoping through the spark plug holes cannot detect scoring in these engines? Yes, the damage to the piston skirt first occurs at the bottom of the cylinder but that damage effects the skirt just below the rings all the way to the bottom of the skirt. As the piston arrives at TDC the skirt damage transfers damage to the cylinder wall the full length of the stroke. Bore scoping through the plug hole may not detect the very first moment of the scoring process, but at the speed that metal is moving back and forth it would seem that some scoring on the full length of the piston stroke would not take long to show up. In the photo there are two oval shaped black areas of damage that appear to show where areas of very tight or zero clearance went into a soft seizure thus causing coating failure and metal to metal damage. The effects of that damage then damage the bore up to TDC. This is how I interpret the above discussions and I will continue to bore scope my Porsche through the plug holes.
04-18-2019, 12:51 PM
