Not using an Oxygen sensor
06-07-2012, 01:27 PM
#17
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There is simply no good reason to run without an O2 sensor. It allows the engine computer to keep the fuel mixture at just the right amount unless you are at full throttle. At full throttle, the O2 sensor is bypassed and the built-in fuel map is used to keep the engine slightly rich for safety. Get a proper bung, put the O2 sensor in there and hook it up.
Dan
'91 928GT S/C
475hp/460lb.ft
Dan
'91 928GT S/C
475hp/460lb.ft
06-07-2012, 01:50 PM
#18
Correct but his car before the by pass was not using an 02 , now after is not so HIS will be running much the same ! NEITHER is right ! He needs the sensor working now and needed it before as well !
06-07-2012, 02:10 PM
#20
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There is simply no good reason to run without an O2 sensor. It allows the engine computer to keep the fuel mixture at just the right amount unless you are at full throttle. At full throttle, the O2 sensor is bypassed and the built-in fuel map is used to keep the engine slightly rich for safety. Get a proper bung, put the O2 sensor in there and hook it up.
Dan
'91 928GT S/C 475hp/460lb.ft
Dan
'91 928GT S/C
475hp/460lb.ftEven brand new Porsche race cars use an oxygen sensor to control the mixture.
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greg brown
714 879 9072
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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!
06-07-2012, 02:13 PM
#21
Official Bay Area Patriot
Fuse 24 Assassin
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The O2 is probably the best way to tell the ECU whether the car is running rich or lean and make the necessary adjustments to injector and ignition timing for a perfect balance. Today, wideband sensors are great and incredibly accurate in these calculations.
06-07-2012, 08:52 PM
#22
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Thread Starter
WOW~~~~
So, i put the car back on the ramps and plotted my next move...Now this was before i read all of the recent post...haha..
The bung goes all the way thru but the cross pipe is not open...I will have a hole cut in and drill into the active pipes to allow flow thru...
Thats on my list for tomorrow..
thnx guys!!!!
I have 2.. 02 sensors the one that came off the original cats, and the one that was given to me with the cross pipe..
I am now testing to see if they are both operational..
Man i really dig this car!!
So, i put the car back on the ramps and plotted my next move...Now this was before i read all of the recent post...haha..
The bung goes all the way thru but the cross pipe is not open...I will have a hole cut in and drill into the active pipes to allow flow thru...
Thats on my list for tomorrow..
thnx guys!!!!
I have 2.. 02 sensors the one that came off the original cats, and the one that was given to me with the cross pipe..
I am now testing to see if they are both operational..
Man i really dig this car!!
06-07-2012, 10:23 PM
#23
Nordschleife Master
I have two 928's with no O2 sensor from factory (ex-UK 87 and 89 S4's - the UK didn't get factory cats/O2 sensors until 1990).
They do run fairly rich, especially at the top end of the rpm range, and put out some smoke in the process.
The WSM contains the specs (1% CO at idle) for adjusting idle mixture to calibrate the MAF signal for the LH on a periodic basis, but if that isn't done, then the car gets progressively leaner as the MAF ages, which probably explains why its so rich to start with.
I converted my old 87 (since sold, as it had a sunroof) to run with an O2 sensor - I had to drill the hole in the floorpan for the O2 sensor cable to run through, as well as changing the LH coding plug to work with the sensor. It did make the car run less rich, and the side benefit is that as the MAF ages, the car will compensate the mixture automatically - which masks the effect of MAF aging until the MAF is really dire.
On an O2-equipped car, you can test your MAF performance by disconnecting the battery, as the LH doesn't save the adaptation parameters, and it'll take some driving to re-adapt to the signal its getting from the O2. If the car runs dramatically worse after a battery disconnect until the O2 loop has adapted, then your MAF should probably be replaced.
In a couple of months I'll be converting my 89 to use the O2 loop based off a simulated narrow band signal from my Tech Edge WBO2. I just need to get other projects out the way.
They do run fairly rich, especially at the top end of the rpm range, and put out some smoke in the process.
The WSM contains the specs (1% CO at idle) for adjusting idle mixture to calibrate the MAF signal for the LH on a periodic basis, but if that isn't done, then the car gets progressively leaner as the MAF ages, which probably explains why its so rich to start with.
I converted my old 87 (since sold, as it had a sunroof) to run with an O2 sensor - I had to drill the hole in the floorpan for the O2 sensor cable to run through, as well as changing the LH coding plug to work with the sensor. It did make the car run less rich, and the side benefit is that as the MAF ages, the car will compensate the mixture automatically - which masks the effect of MAF aging until the MAF is really dire.
On an O2-equipped car, you can test your MAF performance by disconnecting the battery, as the LH doesn't save the adaptation parameters, and it'll take some driving to re-adapt to the signal its getting from the O2. If the car runs dramatically worse after a battery disconnect until the O2 loop has adapted, then your MAF should probably be replaced.
In a couple of months I'll be converting my 89 to use the O2 loop based off a simulated narrow band signal from my Tech Edge WBO2. I just need to get other projects out the way.
