I just had my car dynod and I would appreciate any feedback from tuners on the AFR plots. I'm concerned that it might be a little lean. AFR reading was done at the tailpipe, and unfortunately they didn't capture AFR for the first run. They stopped the second run a little short of redline around 6300 rpm. The 3rd pull had AFR's staying right around 12 from 4000 RPM and up.

The car is an '02 WRX. My only hardware mods are a bosal downpipe and a USDM STI muffler. Everything else is stock (stock up-pipe with cat, stock 3rd cat and resonator pipe, stock intercooler hoses). I'm using cobb stage 2 93 octane map (v 1.20). The car runs 93 octane always and that's what was in the tank during the dyno runs.

I'm very satisfied power wise, but do the AFR numbers look good?


http://erikandersson.home.comcast.net/images/dyno.jpg



thanks,
erik

A/F ratio readings aren't accurate if the sensor's after a cat.

peace

^^^^ Ditto

that's what i thought. the cats add oxygen which would make the AFR readings higher. i guess i wasted my extra $25.

I have ran hundreds of cars on the dyno and I use an LM1 WB meter that I install where the rear o2 sensor is. The difference after the cat is minimal if any at all at WOT. Even with a cat your AFR in my opinion is very lean.

Clark

Looks too lean to me.

Also, if anyone has comments on O2 readings with respect to cats, this thread would like info:

http://forums.nasioc.com/forums/showthread.php?t=415759

They look lean, even by Cobb's map notes:

Cobb Stage 2 1.20 Map Notes (http://www.cobbtuning.com/wrx/accessport/docs02/stage2%2093%20oct.txt)

Target A/F Ratios are mid 12's under load before the onset of boost. Under full load by 3500 RPM the A/F Ratio will drop to mid 11:1 and gradually run richer as RPM's increase ending at mid to high 10:1 A/F at redline.

thanks Clark and others, i'll be switching back to stock i guess until i find out what is going on. i just got the run file data for the two runs with AFR data. i don't understand how the car can run so well if it's that lean :confused: shouldn't there be a dip in the torque from timing being pulled? shouldn't i hear some detonation or something?


Dynojet Research Inc.
Run Notes: Bosal downpipe, Cobb Stage 2 software, OEM STi muffler
Run Date: 11/2/2004 8:04:30 PM

RunFile_003.drf: 77.04°F 29.47in-Hg Humidity:58% SAE:1.01 Average Gear Ratio:76.38

s RPM x1000 hp ft-lbs Air/Fuel
0.44 2.00 18.70 51.12 14.71
1.33 2.10 46.17 115.48 13.90
1.80 2.20 50.07 119.54 13.57
2.25 2.30 54.41 124.25 13.41
2.69 2.40 58.89 128.87 13.53
3.10 2.50 63.78 133.98 13.59
3.50 2.60 70.49 142.40 13.76
3.88 2.70 76.95 149.69 13.52
4.23 2.80 86.35 161.98 13.39
4.53 2.90 95.80 173.51 13.28
4.83 3.00 107.30 187.84 12.94
5.10 3.10 114.95 194.74 12.77
5.38 3.20 126.77 208.07 12.52
5.62 3.30 133.41 212.34 12.45
5.89 3.40 139.37 215.29 12.47
6.14 3.50 143.24 214.95 12.35
6.39 3.60 148.15 216.14 12.30
6.64 3.70 153.43 217.79 12.27
6.90 3.80 155.25 214.58 12.27
7.14 3.90 161.65 217.70 12.16
7.42 4.00 167.63 220.10 12.17
7.65 4.10 167.98 215.18 12.18
7.90 4.20 173.83 217.38 12.10
8.16 4.30 177.64 216.98 12.15
8.40 4.40 185.95 221.96 12.36
8.67 4.50 189.33 220.98 12.33
8.90 4.60 192.00 219.22 12.22
9.16 4.70 193.11 215.79 12.05
9.41 4.80 197.62 216.23 11.93
9.68 4.90 200.99 215.43 11.81
9.95 5.00 198.18 208.18 11.89
10.20 5.10 200.93 206.92 11.88
10.45 5.20 205.79 207.85 11.81
10.73 5.30 211.52 209.61 11.85
10.98 5.40 209.25 203.52 11.74
11.26 5.50 214.47 204.81 11.69
11.53 5.60 214.15 200.85 11.76
11.80 5.70 214.67 197.80 11.52
12.10 5.80 214.36 194.11 11.59
12.39 5.90 215.46 191.80 11.56
12.68 6.00 213.85 187.19 11.51
12.99 6.10 212.73 183.16 11.53
--------- --------- --------- --------- ---------
MAX: 12.99 6.10 215.46 221.96 14.71
MIN: 0.44 2.00 18.70 51.12 11.51

--------------------------------------------------------------------------------

Dynojet Research Inc.
Run Notes: Bosal downpipe, Cobb Stage 2 software, OEM STi muffler
Run Date: 11/2/2004 8:04:30 PM

RunFile_002.drf: 76.33°F 29.48in-Hg Humidity:59% SAE:1.01 Average Gear Ratio:76.36

s RPM x1000 hp ft-lbs Air/Fuel
0.30 2.00 N/A N/A 15.51
1.18 2.10 44.85 112.17 13.41
1.65 2.20 49.74 118.75 13.25
2.10 2.30 54.76 125.05 13.32
2.53 2.40 59.13 129.40 13.40
2.94 2.50 65.41 137.41 13.50
3.32 2.60 71.85 145.14 13.69
3.69 2.70 79.10 153.87 13.65
4.02 2.80 87.96 164.99 13.57
4.33 2.90 99.27 179.78 13.43
4.61 3.00 110.50 193.45 12.95
4.88 3.10 119.53 202.51 12.69
5.14 3.20 129.13 211.95 12.59
5.40 3.30 134.18 213.56 12.48
5.65 3.40 140.47 216.99 12.53
5.90 3.50 142.58 213.95 12.36
6.16 3.60 147.87 215.74 12.42
6.41 3.70 152.42 216.36 12.36
6.65 3.80 156.46 216.25 12.31
6.91 3.90 156.86 211.25 12.27
7.15 4.00 165.65 217.50 12.23
7.44 4.10 167.96 215.15 12.20
7.66 4.20 169.48 211.93 12.27
7.92 4.30 181.30 221.45 12.23
8.17 4.40 183.47 219.00 12.21
8.42 4.50 187.43 218.75 12.43
8.68 4.60 190.91 217.97 12.36
8.91 4.70 191.19 213.65 12.10
9.18 4.80 195.94 214.39 11.94
9.43 4.90 198.90 213.19 11.84
9.71 5.00 200.62 210.73 11.83
9.95 5.10 206.21 212.36 11.86
10.22 5.20 208.68 210.77 11.88
10.48 5.30 206.52 204.65 11.83
10.76 5.40 210.49 204.73 11.80
11.03 5.50 213.44 203.82 11.80
11.31 5.60 214.37 201.05 11.79
11.60 5.70 211.82 195.18 11.73
11.88 5.80 212.27 192.22 11.81
12.18 5.90 209.03 186.07 11.82
12.49 6.00 210.62 184.36 11.86
12.79 6.10 208.55 179.56 12.08
13.12 6.20 198.72 168.34 12.16
13.47 6.30 197.42 164.58 12.01
13.80 6.40 200.08 164.20 11.94
14.17 6.50 197.75 159.79 12.00
--------- --------- --------- --------- ---------
MAX: 14.17 6.50 214.37 221.45 15.51
MIN: 0.30 2.00 44.85 112.17 11.73

Wait... those logs actually look fine to me. I think everyone is just confused by your graph, which draws the dashed line at 13:1, which is counter to what most other dynographs draw the line at (11:1). A low of 11.5:1 is just about right, I believe.

If anything, I think you're running a tad bit rich.

Am I wrong here guys?

Sergi

you can ignore the line, it's only there to make the graph more readable. according to cobb, the low should be 10:1. plus my car is seeing mid 13's around 3500 rpm when it should be mid 11's.

and people call mbcs dangerous! :lol: ;)

i'd keep my foot off the go pedal in the higher gears until you get that figured out.

i will say though that in my experience with the oem ecu maps, the higher the load the richer the mixture. in other words, lean-ish in 1st, 2nd gears = spot on in 3-5th gears. dynos generally load the car LESS than a high gear road pull. who knows how cobb mapped it out though?

ken

He doesn't have an MBC, not from what I could see anyway. . .

Your AFR's are spot on where mine where when I got it measure from my Tailpipe (i had no wbo2). A few weeks later, I put a WB 02 in the DP, didn't change anything else in the car, and my AFR's are TEXTBOOK, spot on every time, right where they should be. I can easily get it into the 10's by 6K. I actually think it's running a little rich, given I can get the AFR's so low so fast. If you were really running that lean, you'd be knocking all over the place and like you said timing would be getting pulled.

If the WB is placed in the DP, right after a cat like clark said, it would be off, but not by as much as if it were just placed in the tail pipe, six feet away from the cat and probably a 800 degree difference in temperature. I think the temperature has more of an effect on the AFR than the cat's do, just my opinion. ,

If anything I bet you're running rich like I am.

If my car is warmed up, I can get my AFR's into the 10's in first gear. The reason I say warmed up is because my WB is in the stock location in my Helix, so it's a couple feet from my turbo, so sometimes when I first run it, the gases aren't as hot as ideal and it gives the appearance of running lean. By a couple runs, I'm well into the 10's in EVERY gear by 6K.

He doesn't have an MBC, not from what I could see anyway. . .

i realize this. my point was that running on this kind of AFR at WOT is far more dangerous than putting on an MBC set to 1 bar. or hell, even 1.2 bars. i see people spouting all over the place how an MBC will blow up your car and that you should get engine management before you do anything else--but imho an MBC is safer than this! :lol: (note: at least on a pre '04 ecu.)

If the WB is placed in the DP, right after a cat like clark said, it would be off, but not by as much as if it were just placed in the tail pipe, six feet away from the cat and probably a 800 degree difference in temperature. I think the temperature has more of an effect on the AFR than the cat's do, just my opinion. ,

sorry, but that opinion is just wrong. how does the oxygen content of the exhaust gas have anything to do with the temperature gradient along the length of the tailpipe.

If anything I bet you're running rich like I am.

jm2c, but i've never heard of a cobb map running rich.

If my car is warmed up, I can get my AFR's into the 10's in first gear. The reason I say warmed up is because my WB is in the stock location in my Helix, so it's a couple feet from my turbo, so sometimes when I first run it, the gases aren't as hot as ideal and it gives the appearance of running lean. By a couple runs, I'm well into the 10's in EVERY gear by 6K.

your shift in AFR is NOT due to warming up your WBo2 sensor, i can assure you that.

you should look into shifts in AFR due to exhaust gas contamination when measured via a tailpipe wideband. there are threads on this very topic.

ken

sorry, but that opinion is just wrong. how does the oxygen content of the exhaust gas have anything to do with the temperature gradient along the length of the tailpipe.

your shift in AFR is NOT due to warming up your WBo2 sensor, i can assure you that.Please read The Technology of Oxygen Sensors (http://www.autospeed.com/cms/article.html?&A=0618). The operating temp of the O2 sensor will effect the output. Note: while the majority of the article relates to normal O2 sensors, WB sensors are affected very similarly.

The WB02 shouldn't read anything until it's up to temp. I've never observed any fluxuations from my LM-1 once it's started providing data. I suspect it's more likely that the car is actually running lean during warmup.

are you trying to tell me that the WB used on that dyno chart doesn't have a heater?

'cuz my bosch wideband sensor controlled by my tuner pro certainly does a perfectly good job of maintaining its own internal temperature reference. perhaps my equipment is better than that of the tuning shop...

i'm tired of handholding. i told you where to look for your lean wideband output. IT IS NOT IN THE TEMPERATURE.

I think if it were an operating temperature issue, we would see a difference between runs because the first run would warm up the sensor. here's a plot from the same dyno, same day. It's a stock sti before and after adding a k&n intake. As you can see, his AFRs are quite normal, and he has all the cats on his car. this is proof enough for me that my readings are accurate. i'm waiting for help from cobb, they're at the SEMA show this week.

http://hig.beesecure.org/photos/subaru/images/aaronwrx_kn_test.jpg

are you trying to tell me that the WB used on that dyno chart doesn't have a heaterIf it's got a heater, then you are right! :D

i realize this. my point was that running on this kind of AFR at WOT is far more dangerous than putting on an MBC set to 1 bar. or hell, even 1.2 bars. i see people spouting all over the place how an MBC will blow up your car and that you should get engine management before you do anything else--but imho an MBC is safer than this! :lol: (note: at least on a pre '04 ecu.)

well my afr's were just like his when read from the tail pipe, and with a WB in the DP they are textbook. I changed nothing on the car, so I highly freckin doubt my AFR's just mysteriously got lower by two points when I installed the WB. And how many people have blown up their rides with the AP compared with how many have blown up thier ride with an MBC?


sorry, but that opinion is just wrong. how does the oxygen content of the exhaust gas have anything to do with the temperature gradient along the length of the tailpipe.

It has to do with the temperature of the exhaust gases. The ideal temperature for a correct reading of air and fuel is NOT the temperature found at the tail pipe. IT's not just the temperature of the probe, but the temp of the gases too, that's why they say you should mount it 6 inches from the turbo.

How many car makers put thier primary monitoring 02 sensors after a cat? or in the tail pipe?? tuners do it because it's easy, not because it's right.



jm2c, but i've never heard of a cobb map running rich.

Sometimes mine get into the 10's around 5K.



your shift in AFR is NOT due to warming up your WBo2 sensor, i can assure you that.

I never said it was becuase the sensor wasn't warm, I was saying that the gases haven't gotten to the proper CONSISTENT temperature to give acurate AFR readings because mine is so far down stream.



ken


You can talk to cobb all day long, and they'll tell you same thing all day long: that readings from the tailpipe are NOT ACURATE. The only way to find out what your AFR's really are is to get a WB and plug the thing in.

You can talk to cobb all day long, and they'll tell you same thing all day long: that readings from the tailpipe are NOT ACURATE. The only way to find out what your AFR's really are is to get a WB and plug the thing in.

I've run with 2 widebands, one in the DP and one in the tail. They booth had the same readings minus a very small delay.

I've run with 2 widebands, one in the DP and one in the tail. They booth had the same readings minus a very small delay.

RIght, there have been 02's that have been acurate at the tail pipe, but not EVERY 02 is acurate there.

The only reason I even posted was because of my experience with what he was talking about. My AFR plot was practicaly identical when read from my tail pipe on the dyno, but with a WB in the DP it was spot on. Maybe the tailpipe is acurate and he's really running 12's. Call cobb and talk to them, i know i have about the same thing. . . . (when I got my dyno results I was scurred). Try to borrow someone's WB and plug it into the DP and see what numbers you get.

Kingpin,

Do you have any readings to back this up? Not that I have hundreds of dyno runs to back it up but it just doesn't make any logical sense that a wide band 02 reading at the tailpipe would be even close to the same as before all cats.

Keith


I have ran hundreds of cars on the dyno and I use an LM1 WB meter that I install where the rear o2 sensor is. The difference after the cat is minimal if any at all at WOT. Even with a cat your AFR in my opinion is very lean.

Clark

You're not paying attention to his specific choice of words, SilverRush (from 2004...).

"at WOT"

wow jeff. nice followup.

:)

I try ;)

yea this is an old thread. The issue with my readings being so low now that i look back at it had nothing to do with temperature as i origanally thought, but due to poor gas flow. The sensor was simply laying in the tail pipe. But nonetheless, the reading was WAAYYY off. And at that point, my cobb OTS map was uber rich, as i thought.

I don't know which is scarier, that you seemed to be running lean, or that original O2 readings were so off. Calibration is key to tuning with a WB O2 sensor.

You can talk to cobb all day long, and they'll tell you same thing all day long: that readings from the tailpipe are NOT ACURATE. The only way to find out what your AFR's really are is to get a WB and plug the thing in.

I could talk to anyone, and listen. Which I do very well but the day I saw a wideband in the downpipe spit the EXACT SAME numbers as a wideband in my tailpipe after one cat I believe it doesn't matter if you put it before or after a cat. I've heard of others experiencing the same thing. Even those that say they see differences its insignifigant to the state of the tune. Sure it matters if you are off by a full point but if its 11.1 compared to 11.2 it doesn't mean squat on the average el cheapo (ie Subaru) motor that isn't insanely modified and runs pump gas. It will swing more from shoddy temp correction or a bad tank of gas.

Also the variations you mention after warming up the car aren't from your downpipe inducing heat or whatever. Its the coolant temp and the motor operation as well as cold-enrichment. Yay for easy running motors in the cold! :)