trying to solve slight engine bucking...ideas?
10-12-2014, 09:55 PM
#19
Three Wheelin'
Thread Starter
I replaced the front fuel damper today. It was one I had not done with my intake refresh. It was not original but not super new either. did not have fuel coming out vacuum port...
but with a brand new one in place the car does feel smoother, if not more power. I took it out for a short drive to test just after, but I want a few more drives to be sure that this is it.
but with a brand new one in place the car does feel smoother, if not more power. I took it out for a short drive to test just after, but I want a few more drives to be sure that this is it.
10-12-2014, 10:01 PM
#21
Drifting
A different bucking problem but thought i'd chime in..
I noticed this problem in my '86 911 (also a 5 speed)
I found it to be wear in my CV joints. I think the spring
of the 1/2 shaft is magnified when the cv joint has wear.
The bucking is most noticeable in 1st gear. That was the tip off.
It didn't happen all the time (driving condition dependent) and was
most noticeable at idle speeds pulling into the driveway or garage.
new cv joints solved it.
My 928 does it only a little once in a while in 1st but then again
my 928 has less than half the miles the 911 had.
Now look at how the sunlight hits the headlight recess below.. i love this car.
I noticed this problem in my '86 911 (also a 5 speed)
I found it to be wear in my CV joints. I think the spring
of the 1/2 shaft is magnified when the cv joint has wear.
The bucking is most noticeable in 1st gear. That was the tip off.
It didn't happen all the time (driving condition dependent) and was
most noticeable at idle speeds pulling into the driveway or garage.
new cv joints solved it.
My 928 does it only a little once in a while in 1st but then again
my 928 has less than half the miles the 911 had.
Now look at how the sunlight hits the headlight recess below.. i love this car.
10-12-2014, 10:06 PM
#22
Rennlist Member
Glad you got this solved Mark. You must be near perfection with this car! Now on to the 88.
10-13-2014, 12:28 AM
#23
Three Wheelin'
Thread Starter
A different bucking problem but thought i'd chime in..
I noticed this problem in my '86 911 (also a 5 speed)
I found it to be wear in my CV joints. I think the spring
of the 1/2 shaft is magnified when the cv joint has wear.
The bucking is most noticeable in 1st gear. That was the tip off.
It didn't happen all the time (driving condition dependent) and was
most noticeable at idle speeds pulling into the driveway or garage.
new cv joints solved it.
My 928 does it only a little once in a while in 1st but then again
my 928 has less than half the miles the 911 had.
Now look at how the sunlight hits the headlight recess below.. i love this car.
I noticed this problem in my '86 911 (also a 5 speed)
I found it to be wear in my CV joints. I think the spring
of the 1/2 shaft is magnified when the cv joint has wear.
The bucking is most noticeable in 1st gear. That was the tip off.
It didn't happen all the time (driving condition dependent) and was
most noticeable at idle speeds pulling into the driveway or garage.
new cv joints solved it.
My 928 does it only a little once in a while in 1st but then again
my 928 has less than half the miles the 911 had.
Now look at how the sunlight hits the headlight recess below.. i love this car.
10-29-2014, 04:44 PM
#25
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10-29-2014, 07:06 PM
#26
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I've been working on these cars since they were brand new....fixing the problems the dealer could not repair.
Many of these cars had the lean surge problem from the very beginning. The dealers would throw parts at them, but had their hands tied, in terms of being able to adjust anything, beyond what the factory would let them adjust. I fixed dozens and dozens of these cars, with this problem.
Some of the cars would respond to disconnecting the O2 sensor (which the dealer would never attempt to try). Some were still too lean.
Try this:
The airflow meters came with very high spring tension on the "door", which made the cars excessively lean.
Remove the flow meter. Cut the silicone around the black plastic cover and gently pry the cover off. Inside is a spring mechanism to control the movement of the door. The movement of the door directly determines the mixture through a pair of contacts that rub on a "chip". Confirm that the chip is still completely black and has no areas where the black is worn through to the white area below. You can wipe off the chip, but do not lubricate!
Mark the position of the black wheel with the teeth on the outside with a paint pen or scribe. Lift the edge of the spring that retains the wheel, while holding the wheel from turning (it will unspring rapidly and many turns if you don't keep it from turning!!!!) Move the wheel 10 notches and release the spring.
Bolt the airflow meter back in and retry.
If fixed, clean the cover and re-silicone (don't go crazy....you might want to get that cover off again, someday).
If improved, but not perfect, keep loosening the wheel until you get the performance you want.
If nothing happens, then you will need to dig deeper.
Many of these cars had the lean surge problem from the very beginning. The dealers would throw parts at them, but had their hands tied, in terms of being able to adjust anything, beyond what the factory would let them adjust. I fixed dozens and dozens of these cars, with this problem.
Some of the cars would respond to disconnecting the O2 sensor (which the dealer would never attempt to try). Some were still too lean.
Try this:
The airflow meters came with very high spring tension on the "door", which made the cars excessively lean.
Remove the flow meter. Cut the silicone around the black plastic cover and gently pry the cover off. Inside is a spring mechanism to control the movement of the door. The movement of the door directly determines the mixture through a pair of contacts that rub on a "chip". Confirm that the chip is still completely black and has no areas where the black is worn through to the white area below. You can wipe off the chip, but do not lubricate!
Mark the position of the black wheel with the teeth on the outside with a paint pen or scribe. Lift the edge of the spring that retains the wheel, while holding the wheel from turning (it will unspring rapidly and many turns if you don't keep it from turning!!!!) Move the wheel 10 notches and release the spring.
Bolt the airflow meter back in and retry.
If fixed, clean the cover and re-silicone (don't go crazy....you might want to get that cover off again, someday).
If improved, but not perfect, keep loosening the wheel until you get the performance you want.
If nothing happens, then you will need to dig deeper.
__________________
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
10-29-2014, 08:40 PM
#27
Official Bay Area Patriot
Fuse 24 Assassin
Rennlist Member
Fuse 24 Assassin
Rennlist Member
I used to do something similar with my L-Jet 944 to get it to pass smog. Opening up the AFM and adjusting the tension richened it up at 15 mph on dyno to lower the NOx I remember.
Greg, which way do you move the black dial on 928s to get rid of the bucking? Clockwise or Anti? I am assuming righty-tighty and lefty-loosey for the adjustments.
Greg, which way do you move the black dial on 928s to get rid of the bucking? Clockwise or Anti? I am assuming righty-tighty and lefty-loosey for the adjustments.
10-29-2014, 09:13 PM
#28
Drifting
I used to do something similar with my L-Jet 944 to get it to pass smog. Opening up the AFM and adjusting the tension richened it up at 15 mph on dyno to lower the NOx I remember.
Greg, which way do you move the black dial on 928s to get rid of the bucking? Clockwise or Anti? I am assuming righty-tighty and lefty-loosey for the adjustments.
Greg, which way do you move the black dial on 928s to get rid of the bucking? Clockwise or Anti? I am assuming righty-tighty and lefty-loosey for the adjustments.
and by coincidence moved it 10 places iirc as Greg suggests.
It was a decent performance improvement.
look here: http://forums.pelicanparts.com/porsc...+-to+air+meter
10-29-2014, 09:15 PM
#29
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I've been working on these cars since they were brand new....fixing the problems the dealer could not repair.
Many of these cars had the lean surge problem from the very beginning. The dealers would throw parts at them, but had their hands tied, in terms of being able to adjust anything, beyond what the factory would let them adjust. I fixed dozens and dozens of these cars, with this problem.
Some of the cars would respond to disconnecting the O2 sensor (which the dealer would never attempt to try). Some were still too lean.
Try this:
The airflow meters came with very high spring tension on the "door", which made the cars excessively lean.
Remove the flow meter. Cut the silicone around the black plastic cover and gently pry the cover off. Inside is a spring mechanism to control the movement of the door. The movement of the door directly determines the mixture through a pair of contacts that rub on a "chip". Confirm that the chip is still completely black and has no areas where the black is worn through to the white area below. You can wipe off the chip, but do not lubricate!
Mark the position of the black wheel with the teeth on the outside with a paint pen or scribe. Lift the edge of the spring that retains the wheel, while holding the wheel from turning (it will unspring rapidly and many turns if you don't keep it from turning!!!!) Move the wheel 10 notches and release the spring.
Bolt the airflow meter back in and retry.
If fixed, clean the cover and re-silicone (don't go crazy....you might want to get that cover off again, someday).
If improved, but not perfect, keep loosening the wheel until you get the performance you want.
If nothing happens, then you will need to dig deeper
Many of these cars had the lean surge problem from the very beginning. The dealers would throw parts at them, but had their hands tied, in terms of being able to adjust anything, beyond what the factory would let them adjust. I fixed dozens and dozens of these cars, with this problem.
Some of the cars would respond to disconnecting the O2 sensor (which the dealer would never attempt to try). Some were still too lean.
Try this:
The airflow meters came with very high spring tension on the "door", which made the cars excessively lean.
Remove the flow meter. Cut the silicone around the black plastic cover and gently pry the cover off. Inside is a spring mechanism to control the movement of the door. The movement of the door directly determines the mixture through a pair of contacts that rub on a "chip". Confirm that the chip is still completely black and has no areas where the black is worn through to the white area below. You can wipe off the chip, but do not lubricate!
Mark the position of the black wheel with the teeth on the outside with a paint pen or scribe. Lift the edge of the spring that retains the wheel, while holding the wheel from turning (it will unspring rapidly and many turns if you don't keep it from turning!!!!) Move the wheel 10 notches and release the spring.
Bolt the airflow meter back in and retry.
If fixed, clean the cover and re-silicone (don't go crazy....you might want to get that cover off again, someday).
If improved, but not perfect, keep loosening the wheel until you get the performance you want.
If nothing happens, then you will need to dig deeper
That little "nugget" of information was worth your Rennlist membership fee a million times over.
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."