SAI bypass for P0410; alternate idea
12-26-2013, 01:34 PM
#16
"Maybe! But in the Great State of Texas, one may pass an emissions test in a 96-98 OBD2 993 with up to two non constant monitoring codes in the not-ready state. Is the law not the same in the peoples republic?"
But that's the on-coming 993 OBDII issue that most all fail to understand,
i.e. All monitors (readiness codes) must be set (passed) before ANY are
indicated when scanned by an OBDII tester. That's unique to the 993
and not like domestic vehicles.
From http://www.systemsc.com/codes.htm
"Notes: The above cycle flags when completed (set) comprise one trip. After completion of the
1st trip, the engine is stopped (cycle flags reset) & restarted to begin the 2nd trip, followed by
a 3rd trip if necessary. A cold engine is required between trips for the SAI test if not using the
Short Test. If the engine is stopped, e.g. stalled, before completion of the trip, the trip must be
restarted from the beginning & all completed cycle flags are reset for that trip. Once all the
necessary trips have been completed, the readiness codes will be indicated by an OBDII scanner."
But that's the on-coming 993 OBDII issue that most all fail to understand,
i.e. All monitors (readiness codes) must be set (passed) before ANY are
indicated when scanned by an OBDII tester. That's unique to the 993
and not like domestic vehicles.
From http://www.systemsc.com/codes.htm
"Notes: The above cycle flags when completed (set) comprise one trip. After completion of the
1st trip, the engine is stopped (cycle flags reset) & restarted to begin the 2nd trip, followed by
a 3rd trip if necessary. A cold engine is required between trips for the SAI test if not using the
Short Test. If the engine is stopped, e.g. stalled, before completion of the trip, the trip must be
restarted from the beginning & all completed cycle flags are reset for that trip. Once all the
necessary trips have been completed, the readiness codes will be indicated by an OBDII scanner."
12-26-2013, 01:46 PM
#17
Rennlist Member
Ron, I am an optimist, but it appears Loren has forecast great rains upon your bonfire.
Thanks for the clarification Loren.
Thanks for the clarification Loren.
12-28-2013, 02:58 PM
#18
The circuit worked for me for several months of driving (2-3 drives per week) but then the CEL light returned. It solves the problem of getting the smog check done but it seems unfortunately not a permanent solution. And then there is my brother-in-law’s 933 which never had this problem with 160K miles. I believe there are two short comings in the current circuit.
- There are times when the pump is activated but the vacuum controlled valve right before the secondary air manifold is not open and the computer does not expect the lean condition on the O2 sensors. Somehow the circuit should read if this valve is open or closed and determine if the lean condition is needed.
- Also I believe the circuit should not ground the O2 sensors but provide some minimum resistance so the reading is not zero but just very lean.
I don’t agree Wolfk since recording the O2s on a working SAI system shows the O2 readings as extremely lean. The air injected is to burn any unburned fuel in the exhaust during the cold cycle reducing HC emissions.
With that said, I’m pulling my exhaust this next month to clear the ports. Hopefully I don’t break a stud and create a bigger problem.
Happy New Year everyone.
- There are times when the pump is activated but the vacuum controlled valve right before the secondary air manifold is not open and the computer does not expect the lean condition on the O2 sensors. Somehow the circuit should read if this valve is open or closed and determine if the lean condition is needed.
- Also I believe the circuit should not ground the O2 sensors but provide some minimum resistance so the reading is not zero but just very lean.
I don’t agree Wolfk since recording the O2s on a working SAI system shows the O2 readings as extremely lean. The air injected is to burn any unburned fuel in the exhaust during the cold cycle reducing HC emissions.
With that said, I’m pulling my exhaust this next month to clear the ports. Hopefully I don’t break a stud and create a bigger problem.
Happy New Year everyone.
12-28-2013, 06:31 PM
#19
Quote,
"I don’t agree Wolfk since recording the O2s on a working SAI system shows the O2 readings as extremely lean. The air injected is to burn any unburned fuel in the exhaust during the cold cycle reducing HC emissions."
Please explain further, always like to learn more. Are you saying O2 sensors always show lean and do not cycle from rich to lean during the SAI cycle? Which O2 sensors are you measuring? Pre cat, post cat?
Would also like to know the function of the vacuum operated valve that you mention that is sometimes closed when SAI pump is running. SAI system purpose is to heat up the cats quickly, this is not just Porsche specific, most modern cars use some means of heating cats.
"I don’t agree Wolfk since recording the O2s on a working SAI system shows the O2 readings as extremely lean. The air injected is to burn any unburned fuel in the exhaust during the cold cycle reducing HC emissions."
Please explain further, always like to learn more. Are you saying O2 sensors always show lean and do not cycle from rich to lean during the SAI cycle? Which O2 sensors are you measuring? Pre cat, post cat?
Would also like to know the function of the vacuum operated valve that you mention that is sometimes closed when SAI pump is running. SAI system purpose is to heat up the cats quickly, this is not just Porsche specific, most modern cars use some means of heating cats.
12-29-2013, 06:46 AM
#20
