O2 Sensor Issue... Help Needed
O2 Sensor Issue... Help Needed I was getting my car tuned this weekend and there seemed to be a problem with the O2 sensors or something related. I think we were using EFILive to monitor them. The voltages would not bounce around to maintain stoich when in closed loop while at cruise rpm's. The voltages moved slowly between only a couple tenths of a volt, not between .9 and 0 like they should. Also, no matter what we did to the injector flow rate, the O2's reacted the same way.
The LTFT's on both banks would always drop to -15.6%, no less. The IFR on the 60# injectors was WAY leaner than any other 60# injector he tuned before. He mentioned that the duty cycle was at 1% and maybe they wouldn't flow any less. Is that possible? He said he was practically tuning the injectors as if they were 100# not 60#.
Finally, the car would occasionally go into Open Loop Fault. It would do this randomly and not right away. We swapped out O2 sensors for some other used ones and there was still the same problem, but it seemed to make it a little better, and I guess it didnt go into Open Loop Fault anymore. We tuned it in open loop and it seemed to drive a little better. We put it back to closed loop and it drives like crap, stumbling, bucking, hesitation, etc...
Any comments or ideas will be helpful, thanks!
The LTFT's on both banks would always drop to -15.6%, no less. The IFR on the 60# injectors was WAY leaner than any other 60# injector he tuned before. He mentioned that the duty cycle was at 1% and maybe they wouldn't flow any less. Is that possible? He said he was practically tuning the injectors as if they were 100# not 60#.
Finally, the car would occasionally go into Open Loop Fault. It would do this randomly and not right away. We swapped out O2 sensors for some other used ones and there was still the same problem, but it seemed to make it a little better, and I guess it didnt go into Open Loop Fault anymore. We tuned it in open loop and it seemed to drive a little better. We put it back to closed loop and it drives like crap, stumbling, bucking, hesitation, etc...
Any comments or ideas will be helpful, thanks!
Last edited by Ferocity02; May 29, 2005 at 12:18 AM.
First off, your buddy does not need to be tuning the injectors as if they are anything else OTHER than 60#ers.
Second, if you have a dead O2, its oscillation will be flatlined and fairly obvious, and you car would also be doing funny things unless forced into open loop.
If you are having negative trimming, then it's apparent that you are holding a rich condition and need to work with VE/MAF tuning to bring you trims back to a good place.
What are your mods, any codes thrown, throw out some info for the EFILive guys so they can offer some help.
Second, if you have a dead O2, its oscillation will be flatlined and fairly obvious, and you car would also be doing funny things unless forced into open loop.
If you are having negative trimming, then it's apparent that you are holding a rich condition and need to work with VE/MAF tuning to bring you trims back to a good place.
What are your mods, any codes thrown, throw out some info for the EFILive guys so they can offer some help.
Originally Posted by Ferocity02
Ttt 
Do you have a regulator on the car? Sometimes tuning 60lb injectors dont go well without having a way to regulate the fuel pressure. This helps alot.
Also, like Tex said, -15 trims means a way rich condition all the time. Now is this under part throttle driving on the street or on the dyno? Two different worlds. There is no load on the dyno for part throttle. And how much time did you give the car to relearn the fuel trims? What was the scaling for the IRA rate, maybe you may seem its lean, but just may not be in the right area. Also, did the tuner build a VE table for the new cam and charger? Working with all these things will fix your problems as well as the correct scaling for the MAF after building a VE table. Hope this helps.
Rick
9 Second Club
Joined: Nov 2001
Posts: 1,445
Likes: 0
From: Bay Area, CA
KPA 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20
IFR 5.96 5.98 6.04 6.06 6.10 6.14 6.16 6.22 6.24 6.28 6.30 6.34 6.38 6.42 6.46 6.50 6.54
and tried as lean as
8.34 8.37 8.46 8.48 8.54 8.60 8.62 8.71 8.74 8.79 8.82 8.88 8.93 8.99 9.04 9.10 9.16
I tried scaling the maf tables 10% down to lean the car out, same stuff, I also tried decreasing the VE tables 40KPA and down 400-3200 30% down o2 sensors responded the same exact way, Injector pulsewidth didnt budge even when the 02 sensors told the car to lean out from the -15.6 condition.
Now I normally would think its tuning, BUT since it went to -15.6 everytime at all IFRs VE and maf adjustments, something pysical must be wrong, I swapped in some 02s that were diffent but now new, didnt have a MAF to try, but that is the next logical step.
Oh BTW closed loop operation the car would NOT run at stoich 14.7:1 AFR it would run around 12.5:1 or so, another reason for the maf or 02s to be messed up. I have tuned these injectors successfully, with Ltrims perfect at 0 to -3 at all load conditions on the street, so I dont see why this car is any different with especially with a cam as mild as a TR224-114. the car also threw an open loop fault code, so something is going on.
IFR 5.96 5.98 6.04 6.06 6.10 6.14 6.16 6.22 6.24 6.28 6.30 6.34 6.38 6.42 6.46 6.50 6.54
and tried as lean as
8.34 8.37 8.46 8.48 8.54 8.60 8.62 8.71 8.74 8.79 8.82 8.88 8.93 8.99 9.04 9.10 9.16
I tried scaling the maf tables 10% down to lean the car out, same stuff, I also tried decreasing the VE tables 40KPA and down 400-3200 30% down o2 sensors responded the same exact way, Injector pulsewidth didnt budge even when the 02 sensors told the car to lean out from the -15.6 condition.
Now I normally would think its tuning, BUT since it went to -15.6 everytime at all IFRs VE and maf adjustments, something pysical must be wrong, I swapped in some 02s that were diffent but now new, didnt have a MAF to try, but that is the next logical step.
Oh BTW closed loop operation the car would NOT run at stoich 14.7:1 AFR it would run around 12.5:1 or so, another reason for the maf or 02s to be messed up. I have tuned these injectors successfully, with Ltrims perfect at 0 to -3 at all load conditions on the street, so I dont see why this car is any different with especially with a cam as mild as a TR224-114. the car also threw an open loop fault code, so something is going on.
He might be getting air let by after the MAF. Did you make sure all the clamps are tight? Plus, what MAF is he using? Maybe he had this problem before all the mods but was never addressed.
Rick
Rick
9 Second Club
Joined: Nov 2001
Posts: 1,445
Likes: 0
From: Bay Area, CA
Maf is stock, car has been previously tuned by me it was fine them when it was cam only. as far as the clamps its possible, but unmetered air after the maf would typically cause a lean condition I would think, but worth checking, I didnt do the install, so I dont know about the clamps definitely something for him to try.
maybe a faulty injector? doubt it since there the car doesnt misfire at all.
maybe a faulty injector? doubt it since there the car doesnt misfire at all.
Trending Topics
Originally Posted by Nickn20
Maf is stock, car has been previously tuned by me it was fine them when it was cam only. as far as the clamps its possible, but unmetered air after the maf would typically cause a lean condition I would think, but worth checking, I didnt do the install, so I dont know about the clamps definitely something for him to try.
maybe a faulty injector? doubt it since there the car doesnt misfire at all.
maybe a faulty injector? doubt it since there the car doesnt misfire at all.
Rick
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Well... I changed the O2's and really hoped my car would gain 100rwhp or at least drive better becasue they are $140 for a pair! I changed them and nothing improved.
Today I checked out the MAF assembly and what not and the MAF is clean with no bent wires. I took some alcohol and q-tips to it to clean it up some more. BUT... the bellow running from the MAF to the TB had two small holes in it for some reason. Both were about 1/4" holes. So basically I was bleeding off metered air because the blower would be pushing air through the MAF and through the holes all the time. Air would never get sucked in through these holes because the pre-intake tract is always pressurized. So maybe that has something to do with it?
Today I checked out the MAF assembly and what not and the MAF is clean with no bent wires. I took some alcohol and q-tips to it to clean it up some more. BUT... the bellow running from the MAF to the TB had two small holes in it for some reason. Both were about 1/4" holes. So basically I was bleeding off metered air because the blower would be pushing air through the MAF and through the holes all the time. Air would never get sucked in through these holes because the pre-intake tract is always pressurized. So maybe that has something to do with it?
TECH Resident
Joined: May 2002
Posts: 829
Likes: 0
From: Fremont, CA
Originally Posted by Ferocity02
Well... I changed the O2's and really hoped my car would gain 100rwhp or at least drive better becasue they are $140 for a pair! I changed them and nothing improved.
Today I checked out the MAF assembly and what not and the MAF is clean with no bent wires. I took some alcohol and q-tips to it to clean it up some more. BUT... the bellow running from the MAF to the TB had two small holes in it for some reason. Both were about 1/4" holes. So basically I was bleeding off metered air because the blower would be pushing air through the MAF and through the holes all the time. Air would never get sucked in through these holes because the pre-intake tract is always pressurized. So maybe that has something to do with it?
Today I checked out the MAF assembly and what not and the MAF is clean with no bent wires. I took some alcohol and q-tips to it to clean it up some more. BUT... the bellow running from the MAF to the TB had two small holes in it for some reason. Both were about 1/4" holes. So basically I was bleeding off metered air because the blower would be pushing air through the MAF and through the holes all the time. Air would never get sucked in through these holes because the pre-intake tract is always pressurized. So maybe that has something to do with it?
Originally Posted by RTCamaroSS
definately possible! it sounds like a good theory, change out that bellow and see if it helps. i would think it would.
Staging Lane
Joined: Feb 2005
Posts: 65
Likes: 0
Look dude, before you go getting excited and re-programming stuff that doesn't need to be like TXhorns281 said. I just went through all the same garbage with my 02 TA on bank 2. Bank 2 sensor 2 was reading next to nothing for Mv on the scanner. I replaced the CAT on bank 2 (passenger side) and all was well.
Good luck
02 TA: Pacesetter LT's, High Flo Cats, Flowmaster Catback
Good luck
02 TA: Pacesetter LT's, High Flo Cats, Flowmaster Catback