X-pipe and lamda sensor
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X-pipe and lamda sensor
On my x-pipe it is two ports for placing the lambda sensor, one on each cylinder bank.
The original set-up measures on a mix from each bank which I guess is the preferred method.
Any comments? Does it matter?
Using a wide-band o2 sensor I have found that there is a slight difference between the two banks. I have the o2 sensor installed on the rich side which means
that the other bank will be forced to stay a bit lean at idle.
a36a4e21f6868aa8290b185e0de70172.jpg
The original set-up measures on a mix from each bank which I guess is the preferred method.
Any comments? Does it matter?
Using a wide-band o2 sensor I have found that there is a slight difference between the two banks. I have the o2 sensor installed on the rich side which means
that the other bank will be forced to stay a bit lean at idle.
a36a4e21f6868aa8290b185e0de70172.jpg
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From: Double Oak, TX
Stock O2 bung on right bank works fine.
For tuning better to use a wide band and listen to the experts.
For tuning better to use a wide band and listen to the experts.
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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."
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From: Oman
Before you start worrying about one bank being a bit richer than the other you should understand that when we measure AFR in Sharktuner the standard deviation for any given cell is typically in the region of 0.3 to 0.4. Thus if the average value is 14.0 at idle [this gives a value of 0.5% for a correct idle or so I understand] the actual point values as measured in the wide band will be in a 14.0 plus or minus 0.4 for some 67% [?] of the sample values. Air flow into each runner is not consistent but the amount of fuel injected is. Those cars fitted with an O2 sensor try to control the AFR value at 14.7 [stoich] but in practice you will see a variation in values.
The only thing that could cause significant variance in AFR from one bank to the other would be if there was a partial blockage in the fuel delivery system after the flow path splits from the common supply- possible but highly unlikely I suspect.
Thus whereas at idle you may see a slight variance in AFR bank to bank, do you see the same variance when the motor is revved or better still, fully loaded? Chances are the difference is statistically irrelevant but if you have any doubts you would need to evaluate what is happening.
Rgds
Fred
The only thing that could cause significant variance in AFR from one bank to the other would be if there was a partial blockage in the fuel delivery system after the flow path splits from the common supply- possible but highly unlikely I suspect.
Thus whereas at idle you may see a slight variance in AFR bank to bank, do you see the same variance when the motor is revved or better still, fully loaded? Chances are the difference is statistically irrelevant but if you have any doubts you would need to evaluate what is happening.
Rgds
Fred
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I dont worry too much about this, but I just think it is interesting. If you look at the figure below you will see that the average AFR at idle is slightly higher for the left bank, maybe 14.3 compared to 13.8 or something for the right one. It is measured with the same sensor, just moved from one side to the other. I guess it is related to some sort of wear in the engine. (Leak down test is ok) I might switch the current location of the lambda sensor from the rich bank (right) to the lean bank(left). That will make sure the left bank to be at an average 14.7 at idle, the other will be forced a little bit rich. I think that will be better than the other way as it is now.
The original location of the lambda sensor makes this less of an issue due to the averaging between the banks. Which I guess is the reason why it was located there.
928_s3_diagnostics.jpg
The original location of the lambda sensor makes this less of an issue due to the averaging between the banks. Which I guess is the reason why it was located there.
928_s3_diagnostics.jpg
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From: ɹəpun uʍop 'ʎəupʎs
Given you have an S3, IIRC the intake is symmetrical, so in your case I'd be looking at getting the injectors cleaned as a first step.
