Dangerous AFR datalog after tune
09-14-2010, 12:40 AM
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Dangerous AFR datalog after tune
I have some personal thoughts about what I'm seeing here, but I'm hoping to get some comments about this tune. As this is the technical Porsche forum, I would appreciate some thoughts.
2007 997 Turbo with ECU + Exhaust/Filter.
94/91 50/50 mix.
About 11K on the odometer, tune was done at 7K.
Thoughts?
2007 997 Turbo with ECU + Exhaust/Filter.
94/91 50/50 mix.
About 11K on the odometer, tune was done at 7K.
Thoughts?
09-14-2010, 02:22 AM
#2
Rennlist Member
What should be a 14.7:1 AFR starts out already low, then goes ridiculous at 5415 rpm.
Some kind of fuel contamination?
Some kind of fuel contamination?
09-14-2010, 03:25 AM
#4
Race Director
[QUOTE=bbywu;7894315]I have some personal thoughts about what I'm seeing here, but I'm hoping to get some comments about this tune. As this is the technical Porsche forum, I would appreciate some thoughts.
2007 997 Turbo with ECU + Exhaust/Filter.
94/91 50/50 mix.
About 11K on the odometer, tune was done at 7K.
Thoughts?
/QUOTE]
Assuming there are no other possible causes.. for instance the fuel pressure remains in spec, and this is confirmed by observation even monitoring during the test, the boost looks good throughout the rpm range, and that the engine otherwise exhibits no untoward behavior, pulls smoothly or at least with no stuttering, blubbering or misfiring, and the check engine light stays off, then my guess would be the mixture goes rich(er) on purpose deliberately done as part of the tune to keep the engine from detonating its brains out or to keep the pistons from softening or the valves from burning.
'course, in looking again from a different point of view at the numbers the hp seems low. I would expect to see more wheel hp than 357. The stock 997 Turbo is rated at IIRC 480hp so assuming a 15% loss attributable to drivetrain I'd expect to see a bit over 400hp wheel hp even with a stock tune provided the engine was healthy.
For a tuned 997 Turbo engine to deliver a bit less than a stock 996 Turbo's (from an engine rated to put out 420hp and estimated to be 357 wheel hp again assuming a 15% loss) suggests perhaps the 997 Turbo engine's numbers may not be due to deliberate enrichment but to a sick engine.
Sincerely,
Macster.
2007 997 Turbo with ECU + Exhaust/Filter.
94/91 50/50 mix.
About 11K on the odometer, tune was done at 7K.
Thoughts?
/QUOTE]
Assuming there are no other possible causes.. for instance the fuel pressure remains in spec, and this is confirmed by observation even monitoring during the test, the boost looks good throughout the rpm range, and that the engine otherwise exhibits no untoward behavior, pulls smoothly or at least with no stuttering, blubbering or misfiring, and the check engine light stays off, then my guess would be the mixture goes rich(er) on purpose deliberately done as part of the tune to keep the engine from detonating its brains out or to keep the pistons from softening or the valves from burning.
'course, in looking again from a different point of view at the numbers the hp seems low. I would expect to see more wheel hp than 357. The stock 997 Turbo is rated at IIRC 480hp so assuming a 15% loss attributable to drivetrain I'd expect to see a bit over 400hp wheel hp even with a stock tune provided the engine was healthy.
For a tuned 997 Turbo engine to deliver a bit less than a stock 996 Turbo's (from an engine rated to put out 420hp and estimated to be 357 wheel hp again assuming a 15% loss) suggests perhaps the 997 Turbo engine's numbers may not be due to deliberate enrichment but to a sick engine.
Sincerely,
Macster.
09-14-2010, 04:41 AM
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I need to see the timing and injector pulsewidth. It looks like the ECU is dumping fuel from knock or misfire. Why would you mix 91 and 94? Buy 94 and run it..
Send me a recent datalog by email and I'll be able to see what is going on.
Send me a recent datalog by email and I'll be able to see what is going on.
09-15-2010, 12:48 AM
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Gentlemen, thank you for your input.
The plot comes from a friend who recently purchased my 997TT - I'm in the process of sorting things out. I was quite surprised at the results of the dyno. I suggested changing plugs and coils, then rerunning the dyno with 94.
Kevin...thanks for the input - I'll pass the data along and repost when I have more.
The plot comes from a friend who recently purchased my 997TT - I'm in the process of sorting things out. I was quite surprised at the results of the dyno. I suggested changing plugs and coils, then rerunning the dyno with 94.
Kevin...thanks for the input - I'll pass the data along and repost when I have more.
