New Member: 996 GT3 timing/knock issues
06-24-2017, 11:18 AM
#31
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06-24-2017, 11:27 AM
#32
Sorry. Lol my elbow decided to text.
its not the mufflers... I had them switched out with no change.
Cam spec:
bank 1: 1.02
bank 2: 7.89
no check engine lights.
One thing I noticed after data logging a friends 6gt3. My engine load is 15% lower. Specially top end.
Any ideas? Been smoked tested which came back negative.
its not the mufflers... I had them switched out with no change.
Cam spec:
bank 1: 1.02
bank 2: 7.89
no check engine lights.
One thing I noticed after data logging a friends 6gt3. My engine load is 15% lower. Specially top end.
Any ideas? Been smoked tested which came back negative.
06-24-2017, 04:14 PM
#34
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With your cam timing -7.89* on bank2 and -1.02 on bank1 I would say that is possibly the main issue. The engine is making different power on bank 1vs 2 but that ECU will not be happy until that issue is solved. That cam timing issue is why b1 and b2 have different fuel trims.
Your load being 15% lower is because with the retarded cam timing the engine is making less power, possibly 10-15% less
ignition timing is being modified and adjusted accordingly. If the engine sees less load it can actually be running and using cells on the timing map slightly lower than the WOT cells and or interpolating. It's possible it is trying to run more timing than it should because of a lower load due to one bank making less power. However b1 having good cam timing it is now possible the adjusted ignition timing is now too advanced for those cylinders and it is knocking and pulling timing.
bottom line. It's possible that you may have to fix the cam timing issue before you can have it not pulling ignition timing.
It is also possible that it is due to either a stretched timing chain and or the bolts have allowed the cams to slip.
If both intake and exhaust cams on b2 are retarded then it's a stretched chain
if only the intake is retarded and exhaust is ok then it may be an issue with the cam actuator to cam.
Your load being 15% lower is because with the retarded cam timing the engine is making less power, possibly 10-15% less
ignition timing is being modified and adjusted accordingly. If the engine sees less load it can actually be running and using cells on the timing map slightly lower than the WOT cells and or interpolating. It's possible it is trying to run more timing than it should because of a lower load due to one bank making less power. However b1 having good cam timing it is now possible the adjusted ignition timing is now too advanced for those cylinders and it is knocking and pulling timing.
bottom line. It's possible that you may have to fix the cam timing issue before you can have it not pulling ignition timing.
It is also possible that it is due to either a stretched timing chain and or the bolts have allowed the cams to slip.
If both intake and exhaust cams on b2 are retarded then it's a stretched chain
if only the intake is retarded and exhaust is ok then it may be an issue with the cam actuator to cam.
06-24-2017, 04:36 PM
#35
Charles. Thank you for your time. I completely understand what you are saying but damn it man, lol that can't be cheap to pull the motor to time it.
Something I noticed. My engine load at idle and low RPMs is much higher than that other 6GT3. I have a much smaller swing between lower RPMs and higher RPMs. Only about 55 points change compared to the other cars with 80 point change.
Here is some data I pulled late yesterday on pump gas. My fuel trims have absolutely gotten much better. The file has quite a few more logging points.
I am fairly certain my timing is off, but not off enough to cause a CEL, porsche specs this at 6 and i think will only throw a code at 10 degrees off.
I completely agree with everything you are saying but just hoping the engine load at lower RPMs might sway our final consensus before I pay to pull the motor.
I sent you a PM. Thanks for all your help fellas. were getting there.
Something I noticed. My engine load at idle and low RPMs is much higher than that other 6GT3. I have a much smaller swing between lower RPMs and higher RPMs. Only about 55 points change compared to the other cars with 80 point change.
Here is some data I pulled late yesterday on pump gas. My fuel trims have absolutely gotten much better. The file has quite a few more logging points.
I am fairly certain my timing is off, but not off enough to cause a CEL, porsche specs this at 6 and i think will only throw a code at 10 degrees off.
I completely agree with everything you are saying but just hoping the engine load at lower RPMs might sway our final consensus before I pay to pull the motor.
I sent you a PM. Thanks for all your help fellas. were getting there.