o2 sensor ; run rich
03-01-2006, 01:19 PM
#1
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o2 sensor ; run rich
Hi,
I seem to have what has been described as a flooded O2 sensor (hesitations in the wet which are gone once I disconnect the plug).
My mechanic advised me to leave it unplugged which would result in no harm to the engine. I read that the engine runs rich which I believe as I failed the emissions test (I succeeded with the reconnected plug though).
Are there negative sides to drive with a disconnected plug?
fuel consumption?
harm to the engine?
It may be subjective, but I think performance has improved with the disconnected plug.
Thanks in advancs
Phil
I seem to have what has been described as a flooded O2 sensor (hesitations in the wet which are gone once I disconnect the plug).
My mechanic advised me to leave it unplugged which would result in no harm to the engine. I read that the engine runs rich which I believe as I failed the emissions test (I succeeded with the reconnected plug though).
Are there negative sides to drive with a disconnected plug?
fuel consumption?
harm to the engine?
It may be subjective, but I think performance has improved with the disconnected plug.
Thanks in advancs
Phil
03-01-2006, 01:41 PM
#2
Burning Brakes
I have had this problem before and you will find your fuel consumption will go up very noticably. I need to get mine checked as I suspect I have the same problem again due to the amount of fuel I seem to be getting through at present.
03-01-2006, 02:14 PM
#3
Three Wheelin'
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Phil... Why not just replace the 02 sensor? They aren't that expensive... And it will keep your car running smoother. Just remember to disconnect your battery to reset the DME after the swap. Then take it out for a "spirited" drive to have the DME "relearn"...
The 02 sensor change is an easy DIY and is located in the DIY section here.
The 02 sensor change is an easy DIY and is located in the DIY section here.
03-01-2006, 05:28 PM
#4
Burning Brakes
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I had serious trouble with mine being practically welded on. I ended up soaking and turning it over the course of several days. I had to have a deep-well type socket and cut the cord. I had an 02 remover tool, but since it had a split in the side it actually spread apart rather then turn the stubborn sensor. Worked fine for the new one in my bypass though. 
03-02-2006, 03:49 AM
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Hi,
I think I go for a replacement then.
The only thing that bothers me is the fact that, in high revs, the enginr really seems stronger with the plug disconnected. Could it be that, with the plug connected, my existing sensor does not work so well, even in the dry?
Regards
Phil
I think I go for a replacement then.
The only thing that bothers me is the fact that, in high revs, the enginr really seems stronger with the plug disconnected. Could it be that, with the plug connected, my existing sensor does not work so well, even in the dry?
Regards
Phil
03-02-2006, 09:15 AM
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Burning Brakes
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If your foot is on the gas to a significant degree (wide open throttle or something near it) your engine should be ignoring the o2 sensor and switching to a richer mixture.
Now I've wondered if the o2 sensor leans and richens everything out long term, possibly even these richened maps to get maximum power. It could be using the o2 sensor to not only keep the perfect mixture during normal driving but also to adapt its baseline to account for minor vacuum leaks and wear onthe engine. I've asked this question a few times and noone has answered. I know the newer motronic stuff does this per literature about and from Bosch management systems. Anyway, if this is the case and your old sensor wasnt working right it could have been leaning all the maps or richening all the maps. When you disconnected the sensor the ccu threw up a red flag and immediately ignored all the adapting it had done on that bad sensor? I really don't know, just speculation.
Now I've wondered if the o2 sensor leans and richens everything out long term, possibly even these richened maps to get maximum power. It could be using the o2 sensor to not only keep the perfect mixture during normal driving but also to adapt its baseline to account for minor vacuum leaks and wear onthe engine. I've asked this question a few times and noone has answered. I know the newer motronic stuff does this per literature about and from Bosch management systems. Anyway, if this is the case and your old sensor wasnt working right it could have been leaning all the maps or richening all the maps. When you disconnected the sensor the ccu threw up a red flag and immediately ignored all the adapting it had done on that bad sensor? I really don't know, just speculation.
03-02-2006, 12:16 PM
#7
"It could be using the o2 sensor to not only keep the perfect mixture during normal driving but also to adapt its baseline to account for minor vacuum leaks and wear onthe engine. I've asked this question a few times and noone has answered."
The 964 DME ECM does not have this capabilibity as does the 993 OBDII DME ECM
and all other ODBII fuel injection systems. It's called long & short term TRIM.
Check here ( www.systemsc.com/glossary.htm ) for more info.
The 964 DME ECM does not have this capabilibity as does the 993 OBDII DME ECM
and all other ODBII fuel injection systems. It's called long & short term TRIM.
Check here ( www.systemsc.com/glossary.htm ) for more info.