anyone ever turn off front O2 sensors?
11-01-2005, 12:27 AM
#1
Banned
Thread Starter
iTrader: (5)
Join Date: Dec 2001
Location: Fremont, Ca
Posts: 1,461
Likes: 0
Received 0 Likes
on
0 Posts
anyone ever turn off front O2 sensors? I ask this because today I had a car come into my shop for some dyno pulls, and was tuned earlier by a local tuner. Well, I hook up the scanner and come to find out there is nothing comming from the Ltrims and the O2 sensors. The best part is this car is not even in SD mode. The MAF is still running. The O2's are reading rich all the time. So I ask the owner and he said the tuner turned them off because it was difficult to tune. Here is a background on the car. The car is stock with a blower. So I am trying to understand where the hard part is about tuning this car? And why would you shut off the Ltrims and the O2's if the car is not even tuned in Speed Density? Is there some new way of tuning that I missed going on? And this is not the first time I have seen this from the same tuner also. Any ideas?
Rick
Rick
11-01-2005, 12:54 AM
#2
TECH Senior Member
if it's an all out race car then I can see disabling the front O2s .... open loop only tune.... running leaded gasoline
other than that I don't see any reason to disable the front O2s... if the car's not setup for open loop speed density.. then I would guess the previous tuner doesn't understand the difference between front and rear O2s ... and just disabled everything...
another option is the tuner doesn't know what he's doing so he just tunes the cars to run at (ideal) AFR (or rather mathmatical AFR.... not necessarily actual)
whatever the reason.. I can't think of a valid reason other than running leaded gas or in an all out race car... why you'd disable the front O2 sensors
other than that I don't see any reason to disable the front O2s... if the car's not setup for open loop speed density.. then I would guess the previous tuner doesn't understand the difference between front and rear O2s ... and just disabled everything...
another option is the tuner doesn't know what he's doing so he just tunes the cars to run at (ideal) AFR (or rather mathmatical AFR.... not necessarily actual)
whatever the reason.. I can't think of a valid reason other than running leaded gas or in an all out race car... why you'd disable the front O2 sensors
11-01-2005, 01:36 AM
#3
Banned
Thread Starter
iTrader: (5)
Join Date: Dec 2001
Location: Fremont, Ca
Posts: 1,461
Likes: 0
Received 0 Likes
on
0 Posts
I thought the same thing. The thing that I dont get the most is the car is stock internally. So why would it be hard to tune? I have never had problems even with big cams. So go figure.
Rick
Rick
11-01-2005, 09:07 AM
#7
There really needs to be some sort of classification that shows people (non-DYI'ers) looking for tunes, that the professional tuner knows his stuff about EFI. I have heard of many horror stories of how "tuners" tune and have seen some weird stuff. That is one of the worst examples. 
Trending Topics
11-01-2005, 10:41 AM
#8
Teching In
Join Date: Sep 2003
Posts: 49
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Flame Throwing SS
There really needs to be some sort of classification that shows people (non-DYI'ers) looking for tunes, that the professional tuner knows his stuff about EFI. I have heard of many horror stories of how "tuners" tune and have seen some weird stuff. That is one of the worst examples.
I agree fully. I for one am sick of seeing crap like this. And too think, its the people that actually tune cars the right way that get all the crap.
Rick
11-01-2005, 10:44 AM
#9
Banned
Thread Starter
iTrader: (5)
Join Date: Dec 2001
Location: Fremont, Ca
Posts: 1,461
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by smokn346
I agree fully. I for one am sick of seeing crap like this. And too think, its the people that actually tune cars the right way that get all the crap.
Rick
Rick
Rick
11-01-2005, 12:55 PM
#10
Originally Posted by TAQuickness
disturbing indeed... especially on a boosted application
Personally I run OLSD and I'm always watching the WB.
Personally I run OLSD and I'm always watching the WB.
My WB guage is in a pillar pod. I once covered it (red LED) as I was annoyed by the constant glare at nite. I became paranoid about the AFR because it's second nature to keep an eye on it......I missed seeing the AFR!!
11-01-2005, 01:06 PM
#11
TECH Junkie
iTrader: (28)
Join Date: Jan 2004
Location: Houston
Posts: 3,250
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Bink
HeHeHe....me too.
My WB guage is in a pillar pod. I once covered it (red LED) as I was annoyed by the constant glare at nite. I became paranoid about the AFR because it's second nature to keep an eye on it......I missed seeing the AFR!!
My WB guage is in a pillar pod. I once covered it (red LED) as I was annoyed by the constant glare at nite. I became paranoid about the AFR because it's second nature to keep an eye on it......I missed seeing the AFR!!
11-02-2005, 08:17 AM
#12
Originally Posted by Rick@Synergy
I ask this because today I had a car come into my shop for some dyno pulls, and was tuned earlier by a local tuner. Well, I hook up the scanner and come to find out there is nothing comming from the Ltrims and the O2 sensors. The best part is this car is not even in SD mode. The MAF is still running. The O2's are reading rich all the time. So I ask the owner and he said the tuner turned them off because it was difficult to tune. Here is a background on the car. The car is stock with a blower. So I am trying to understand where the hard part is about tuning this car? And why would you shut off the Ltrims and the O2's if the car is not even tuned in Speed Density? Is there some new way of tuning that I missed going on? And this is not the first time I have seen this from the same tuner also. Any ideas?
Rick
Rick
I myself have been in open loop for about 6 months(since I bought my longtubes)
teh problem I had was that my o2's were sleepy...even with the bosh 13111 sensors...so fueling was gonna be screwed up no matter what I did...
I didt want to tune with LTFT and have the car be super lean just because it had sleepy o2's and LTFT was like -12 when I knew the teh A/F was correct with my wideband.
I have also tuned the Open loop EQ ratio vs ECT table..(everybody changes this table to all 1.000..but then does nothing about it when they are done....)
at 176-212 my fueling is correct in open loop
and below I had to richen up the mixture multiplier to
get proper fueling
I checked my tune the other day again with my wideband...still solid as a rock with no problems
not saying that everybody should be in open loop...
but if you do, there are more things to tune to get fueling correct.
11-02-2005, 11:51 AM
#13
Banned
Thread Starter
iTrader: (5)
Join Date: Dec 2001
Location: Fremont, Ca
Posts: 1,461
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by soundengineer
it sounds to me like the "tuner" had no clue what he was doing. he probably thought that a blower is dangerous for the car unless its rich all the time....and didnt understand that teh car is going to command stoich all the time unless in PE
I myself have been in open loop for about 6 months(since I bought my longtubes)
teh problem I had was that my o2's were sleepy...even with the bosh 13111 sensors...so fueling was gonna be screwed up no matter what I did...
I didt want to tune with LTFT and have the car be super lean just because it had sleepy o2's and LTFT was like -12 when I knew the teh A/F was correct with my wideband.
I have also tuned the Open loop EQ ratio vs ECT table..(everybody changes this table to all 1.000..but then does nothing about it when they are done....)
at 176-212 my fueling is correct in open loop
and below I had to richen up the mixture multiplier to
get proper fueling
I checked my tune the other day again with my wideband...still solid as a rock with no problems
not saying that everybody should be in open loop...
but if you do, there are more things to tune to get fueling correct.
I myself have been in open loop for about 6 months(since I bought my longtubes)
teh problem I had was that my o2's were sleepy...even with the bosh 13111 sensors...so fueling was gonna be screwed up no matter what I did...
I didt want to tune with LTFT and have the car be super lean just because it had sleepy o2's and LTFT was like -12 when I knew the teh A/F was correct with my wideband.
I have also tuned the Open loop EQ ratio vs ECT table..(everybody changes this table to all 1.000..but then does nothing about it when they are done....)
at 176-212 my fueling is correct in open loop
and below I had to richen up the mixture multiplier to
get proper fueling
I checked my tune the other day again with my wideband...still solid as a rock with no problems
not saying that everybody should be in open loop...
but if you do, there are more things to tune to get fueling correct.
Rick
11-02-2005, 04:21 PM
#17
Banned
Thread Starter
iTrader: (5)
Join Date: Dec 2001
Location: Fremont, Ca
Posts: 1,461
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by soundengineer
to answer the constant high o2 voltage..... thats pretty typical with Open Loop..
they dont oscilate in open loop(henceforth why it is called open loop)
and yeah...it really sounds to me like a half *** tune if it feels crappy at part throttle
they dont oscilate in open loop(henceforth why it is called open loop)
and yeah...it really sounds to me like a half *** tune if it feels crappy at part throttle
I know all about SD tuning. The high voltage is because its dumping fuel. I was only bringing this up because I was curious if anyone has tried doing an open loop tune with the front sensors off and the MAF still working. trust me, I know this is a crap tune.
rick
11-02-2005, 08:52 PM
#18
Originally Posted by WS6FirebirdTA00
its just weird that someone would put an open loop tune on a car with a maf, i dont see the benefits from that.
Originally Posted by Rick@Synergy
I was only bringing this up because I was curious if anyone has tried doing an open loop tune with the front sensors off and the MAF still working.
11-02-2005, 09:08 PM
#19
Originally Posted by NicD
What if you wanted to run leaded gas? Speed density or MAF is irrelevant and OL works the same either way. That and lots of overlap are about the only reasons I can see to run OL and ditch the factory O2s.
Done it quite a few times on some turbo sand rails. Usually just run avgas out at the dunes so obviously O2s won't work for long. Same as any tune really just using a wideband vs MAF freq to dial it in after the appropriate VE tuning.
Done it quite a few times on some turbo sand rails. Usually just run avgas out at the dunes so obviously O2s won't work for long. Same as any tune really just using a wideband vs MAF freq to dial it in after the appropriate VE tuning.
As long as you have tuned in the MAF with a wideband to ensure proper fueling...adn teh VE has been tuned in as well
thats why dry shot guys like the MAF(until they max it out..LOL)
It reports whats really happening with the air and as long as you have teh righ #'s in teh table t doesnt matter what the temperature....or humidity....
or anything...It comes out right...
11-02-2005, 09:14 PM
#20
my reasoning is that the maf is not perfect at all and can introduce a lot of fueling error. I would prefer to run SD so you dont have those errors, and its just odd that someone goes through all that and puts the MAF back on the car. i just have a hard time relying on a sensor to fuel the car without the car being allowed to make corrections for possible improper fueling. i would much rather tell the car how to run and beon the safe side ya know?