STS Turbo with Wideband
STS Turbo with Wideband Ok guys I need some help. I have the sts kit like it says in the title at #9, FMIC, Meth, 4000 fuddle stall, trans go shift kit, #60 mototron injectors, tune by Nelson performance, newly installed AEM wideband.
Here is my problem, everytime I go WOT my wideband shows a 10.0 all the way till I get out of it. Driving around regular it bounces around about 14.5 15.5 while going 45 mph. I have redialed in these injectors and still something is still causing too much fuel to be dumped in.
PLEASE HELP
oh one more thing I have been to the dyno only once and it was doing the same thing going to 10.0 AFR. I did manage to get 455HP 465TQ and at the time I had #42 injectors, Allen found that my COT was turned on and I thought after turning that off it fixed it. I just got the wideband installed yesterday and its still doing this.
Here is my problem, everytime I go WOT my wideband shows a 10.0 all the way till I get out of it. Driving around regular it bounces around about 14.5 15.5 while going 45 mph. I have redialed in these injectors and still something is still causing too much fuel to be dumped in.
PLEASE HELP
oh one more thing I have been to the dyno only once and it was doing the same thing going to 10.0 AFR. I did manage to get 455HP 465TQ and at the time I had #42 injectors, Allen found that my COT was turned on and I thought after turning that off it fixed it. I just got the wideband installed yesterday and its still doing this.
it could be a problem with the wideband location...I had a similiar problem and it turned out I had to relocate my wideband from before passenger side cat to after the turbo to get accurate readings....good luck
TECH Resident
Joined: Mar 2002
Posts: 782
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From: North Las Vegas, NV
Originally Posted by socalstreetracer
it could be a problem with the wideband location...I had a similiar problem and it turned out I had to relocate my wideband from before passenger side cat to after the turbo to get accurate readings....good luck
TECH Resident
Joined: Nov 2002
Posts: 996
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OK, I had the same problem when I first installed my STS kit with 60# injectors. My wideband is located after the turbo also (which means after the cat), and the reading is accurate. 14.7 at idle, etc...
My car would run VERY rich at WOT, and my digital wideband only showed down to "10" as the richest value. The car would also stumble at WOT, since it was too rich.
I had to make some major adjustments to the IFR table to lean it out, and now it runs at 11.0 - 11.5. However, the adjustments I made are not linear, and I do not like the way I had to get it to run "right". (2003 Z06). Anyway, maybe it is something with these injectors? I don't know...
Below are my IFR values, starting from 0.0 inHG to 23.6 inHG. Notice that at WOT, I actually set the IFR to show more flow, which is the opposite of what should happen. (ie. under boost the injectors should have LESS flow)
68.019316
64.981079
62.996924
59.400642
59.772672
60.020691
60.392720
60.764749
61.136778
61.508807
61.880836
62.128856
62.500885
62.872914
63.120933
63.492962
63.864991
Anyway, my car runs like a monster and it never goes lean, so I'll keep it this way for now.
Tommy
My car would run VERY rich at WOT, and my digital wideband only showed down to "10" as the richest value. The car would also stumble at WOT, since it was too rich.
I had to make some major adjustments to the IFR table to lean it out, and now it runs at 11.0 - 11.5. However, the adjustments I made are not linear, and I do not like the way I had to get it to run "right". (2003 Z06). Anyway, maybe it is something with these injectors? I don't know...
Below are my IFR values, starting from 0.0 inHG to 23.6 inHG. Notice that at WOT, I actually set the IFR to show more flow, which is the opposite of what should happen. (ie. under boost the injectors should have LESS flow)
68.019316
64.981079
62.996924
59.400642
59.772672
60.020691
60.392720
60.764749
61.136778
61.508807
61.880836
62.128856
62.500885
62.872914
63.120933
63.492962
63.864991
Anyway, my car runs like a monster and it never goes lean, so I'll keep it this way for now.
Tommy
darkblue-what happened with me was on the dyno wideband(sensor in tailpipe) I was getting lean readings that my aem gauge wasnt seeing...my in car gauge said 11.0 and the car made no power...so I based my tuning changes off the dyno wideband which was showing different things than my aem(sensor before cat) such as lean spikes....I began tuning based off the dyno wideband readings and made power and the difference in air/fuel readings were huge...I mean at one point I was getting lean spikes over 15.0 and getting kr...the in car gauge was still read 11.0..(I sent back the sensor and it works fine)...so I relocated the sensor to after the trubo...now I have accurate tuning, no more kr and make decent power..just my experience. I also called aem, dynojet asking about why this would happen, they both said it must have something to do with exhaust pressure at high rpm. Just my experience
TECH Resident
Joined: Nov 2002
Posts: 996
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Yes, I believe placing the wideband before the turbo yields inaccurate results because the wideband sensor is calibrated to "normal" barometric pressure. There is a pressure buildup before the turbo, so the reading is not true.
Tommy
Tommy
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Launching!
Joined: Jan 2002
Posts: 299
Likes: 41
From: Detroit, Murder City
Exhaust pressure influences the way that wideband O2's read. The short story is that they are rated for 0.8-1.1atm pressure for "normal" use. Measuring in front of the turbine will surely yield higher pressures under load and skew the signal. Basically, it tend to exaggerate the signal. I.E. "rich" looks even richer and "lean" looks even leaner to the sensor at elevated pressure.
There are equations to normalize the readings based on pressure, but it's usually easier to just measure lambda at a place where exhaust pressure is more "normal". (After the turbo)
There are equations to normalize the readings based on pressure, but it's usually easier to just measure lambda at a place where exhaust pressure is more "normal". (After the turbo)
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Verdad Gallardo TECH Resident
Joined: Mar 2002
Posts: 782
Likes: 0
From: North Las Vegas, NV
Originally Posted by socalstreetracer
they both said it must have something to do with
exhaust pressure at high rpm. Just my experience
exhaust pressure at high rpm. Just my experience
ws6Vixen that is what I thought too. Are you doing your own tune?
If so do you have hptuners and can you shoot me over a email of that tune just so I can compare them? I have been trying to get someone else that has a STS to help me out and let me compare tunes.
As for the 12 bolt I do not have one that is with the stock 10 bolt.
If so do you have hptuners and can you shoot me over a email of that tune just so I can compare them? I have been trying to get someone else that has a STS to help me out and let me compare tunes.
As for the 12 bolt I do not have one that is with the stock 10 bolt.
Let me see if I have this right...I have my wideband mounted in my y-pipe (no cats on the car), so I would be getting incorrect readings!?!?! Holy crap, I guess I need to move that thing ASAP!
I have my cats gutted. And was told by Allen Nelson that he has installed the widebands before the cats and then some after the turbo and is saying there is no difference between the 2. As far as his external dyno wideband reads.
PS Is there anyway to tell at all if this thing is even close?
I have HPTuners and before I got the wideband he was telling me to make sure the O2B1S1 and O2B2S1 stayed around 920 at WOT and they do but right now that still doesnt help me does anyone else have a idea
PS Is there anyway to tell at all if this thing is even close?
I have HPTuners and before I got the wideband he was telling me to make sure the O2B1S1 and O2B2S1 stayed around 920 at WOT and they do but right now that still doesnt help me does anyone else have a idea
There was a post in the tuning section a while ago with a link to a post where a reparable shop in Australia did a test using 2 of the same brand WB, calibrated at the same time and installed on each side of the cat (before and after). The results of the test, is there's was no measurable differences in the reading in before or after the cat after several dyno pulls. I know I tune my STS with my WB after the turbo which is after the cats, without any problems.
Staging Lane
Joined: Feb 2005
Posts: 73
Likes: 0
Nelson performance probably set the ve table to a "safe" afr of 10:1. If you are running a 1 bar map sensor, the ve table is what is used to adjust A/F. You can do it with the IFR table but that is not the proper way. As soon as you go WOT the computer is commanding 10:1 AFR.
Launching!
Joined: Jan 2002
Posts: 299
Likes: 41
From: Detroit, Murder City
To clarify:
If the catalyst is a "good" one with minimal pressure drop across it, there shouldn't be any measured change from a wideband across it.
If your turbo is functioning such that there is significant pressure drop across the turbine section (as in most common, engine-mounted turbos) the higher pressure on the engine side can skew the readings from a wideband O2.
Attempting to tune WOT with a narrow band HEGO for anything other than lambda=1 is just begging for broken ****.
For gasoline: Lambda = (Actua A/F ratio)/(Stoichiometric ratio)
= (Actual A/F)/14.64
It's an engineering unit used by OEM calibrators where numbers lower than 1.0 are richer than stoichiometric.
If the catalyst is a "good" one with minimal pressure drop across it, there shouldn't be any measured change from a wideband across it.
If your turbo is functioning such that there is significant pressure drop across the turbine section (as in most common, engine-mounted turbos) the higher pressure on the engine side can skew the readings from a wideband O2.
Attempting to tune WOT with a narrow band HEGO for anything other than lambda=1 is just begging for broken ****.
For gasoline: Lambda = (Actua A/F ratio)/(Stoichiometric ratio)
= (Actual A/F)/14.64
It's an engineering unit used by OEM calibrators where numbers lower than 1.0 are richer than stoichiometric.
I think people dont realize how much pressure builds up in front of the CAT's. Saw a test around here somewhere that put pre-cat @ 5 PSI and after @ .8 PSI. Now add front mount turbo to the mix: typically the turbo is pre-cat, so the backpressure IT creates the CAT's never see, but the turbo and hot side see an increase because of the CAT. Good rule of thumb IMHO used to be if you have 5 PSI boost you have 10 PSI ahead of the turbo on a good flowing setup. Myself I have seen higher ratio's than that on a few street setups.
OK now lets remove the front mount and add the post-CAT STS @ 5 PSI WFO with CAT's, O-boy! So take the 5 PSI you already had at WFO pre-CAT, add the 10 PSI the STS gave at the cat exit and some MORE fuel because that's what the engine wants to live now and you see where this is going? It's no wonder a wideband wont read it correctly. I'm amazed that any CAT survives this type of environment, even though some dont.
I'm curious if Jose or TRT has seen pressure measurements pre-turbo on the STS and what they have to add?
OK now lets remove the front mount and add the post-CAT STS @ 5 PSI WFO with CAT's, O-boy! So take the 5 PSI you already had at WFO pre-CAT, add the 10 PSI the STS gave at the cat exit and some MORE fuel because that's what the engine wants to live now and you see where this is going? It's no wonder a wideband wont read it correctly. I'm amazed that any CAT survives this type of environment, even though some dont.
I'm curious if Jose or TRT has seen pressure measurements pre-turbo on the STS and what they have to add?