Why so lean at WOT?
....... Are you sure your not overfueling it on the N/A side? If the o2 is seeing fuel it will read it as lean it reads air not fuel. Increase fuel by 20% run it check AFR if it goes more lean your reading fuel. Then decrease fuel 20%(from the original amount) if AFR actually goes down then you know the o2 is reading fuel. Seen this while dyno tuning a few time.
Originally Posted by brad8266
My wideband is reading around the 14.0:1 area during most of my WOT runs. I have already done my closed loop tuning. Stoich is set at 14.737 and in the PE table the multiplier value is set to 1.2403. I am using LS1 Edit as well. Correct me if im wrong, but my A/F commanded is 11.88:1 since 14.737/1.2403 = 11.88 ?? Am I doing this calculation right or what, or does the calculation work different in ls1 edit?? What is the best way to go about getting this AF ratio down to where i want it to be?
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Originally Posted by ESR
Are you sure your not overfueling it on the N/A side? If the o2 is seeing fuel it will read it as lean it reads air not fuel. Increase fuel by 20% run it check AFR if it goes more lean your reading fuel. Then decrease fuel 20%(from the original amount) if AFR actually goes down then you know the o2 is reading fuel. Seen this while dyno tuning a few time.
.... That was my reaction the first time I ran into it when I was tuning a car at Conleys. Basically a o2 sensor is made to read air. In some instances (Im not necessarily saying yours) if a car is over fueled the o2 will see some actual fuel in the exhaust. Since the o2 is meant to read air it will see the fuel in the exhaust as a lean condition 14.0+afr. Yeah I was confused to at first when I ran into it. As a test I would go up 20% on your PE table where your seeing the lean condition and then down 20% from the original numbers. If you take 20% out and the fuel and afr comes down more towards the rich side of the table its probably overfueled. Just have someone watch your wideband readings do stay on it if its lean. Just my .02 I could be totally wrong. Just trying to help.
Originally Posted by brad8266
Ok, you just confused me, lol. I have only been logging under N/A, have not even bothered using the spray lately. What is all this about it reading fuel or air??
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Originally Posted by ESR
That was my reaction the first time I ran into it when I was tuning a car at Conleys. Basically a o2 sensor is made to read air. In some instances (Im not necessarily saying yours) if a car is over fueled the o2 will see some actual fuel in the exhaust. Since the o2 is meant to read air it will see the fuel in the exhaust as a lean condition 14.0+afr. Yeah I was confused to at first when I ran into it. As a test I would go up 20% on your PE table where your seeing the lean condition and then down 20% from the original numbers. If you take 20% out and the fuel and afr comes down more towards the rich side of the table its probably overfueled. Just have someone watch your wideband readings do stay on it if its lean. Just my .02 I could be totally wrong. Just trying to help.
..... Uh........now your confusing me. your table is at 1.2403 multiply that by 20% see what it does then if it goes further lean and probably its overfueled bring the 1.2403 down by 20% and check your AFR both ways this will gauge which way you need to move the PE table.
Originally Posted by brad8266
Ok, so increase my entire pe table from 1.2403 to 1.488 which is 9.9:1 AFR and then it should richen up some. If it richens then go back to 1.2403. which is 11.8:1 AFR Right?
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Ok, on the way home from work a bit ago I unplugged the MAF and drove normal for a while and then did some WOT runs. It is nowhere near as lean as it was with the MAF plugged in. I am now in the ballpark for what my commanded is, it is slightly off. I am in the 12.40 to 11.00 range. Guess I need to richen up the MAF table. After 3 runs I did a nitrous run and was in the 10 to high 11 afr range. I think once I fix the MAF issue I will be OK.
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Update: I went out tonight and did more logging/flashing/calculating. My problem was in the high end of the MAF table. I went back to stock MAF table, added 105% below 4000hz and added 110% above 4000hz. Went out and it was still lean at WOT. So I printed the wideband log (AFR vs. RPM) as well as my WOT area of the ls1scan log. I used the MAf freq and corrosponded it to the associated RPM. I then took that rpm and coorelated it on my wideband log.
Example(made up numbers): At 7000hz and WOT I was at 3500rpms and wideband says 14.0. So I then divided actual AFR by commanded AFR, 14.0/12.8= 109%. I then multiplied the 7000Hz cell by 109%. I ran this calc for each area and chaned each maf cell accordingly. Went back out and tested it out after driving for about half hour. This time WOT AFR was just about right on what I commanded.
I am so damn glad I finally figured it out without doing it the ghetto way by just changing the PE table. Did a nitrous run and actually got richer when activated, I may have to put in a slightly smaller fuel jet. I figured i would post this in case it may help someone else one day that has ls1 edit(almost nobody, lol). Thanks everyone for the help.
Not sure if its just my imagination, but the car now seems like it pulls a lot harder with the AFR on point.
Example(made up numbers): At 7000hz and WOT I was at 3500rpms and wideband says 14.0. So I then divided actual AFR by commanded AFR, 14.0/12.8= 109%. I then multiplied the 7000Hz cell by 109%. I ran this calc for each area and chaned each maf cell accordingly. Went back out and tested it out after driving for about half hour. This time WOT AFR was just about right on what I commanded.
I am so damn glad I finally figured it out without doing it the ghetto way by just changing the PE table. Did a nitrous run and actually got richer when activated, I may have to put in a slightly smaller fuel jet. I figured i would post this in case it may help someone else one day that has ls1 edit(almost nobody, lol). Thanks everyone for the help.
Not sure if its just my imagination, but the car now seems like it pulls a lot harder with the AFR on point.
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Sounds like you fixed it the right way This should help any one having the same problem as you not just people with edit no matter what the softwear the process is pretty much the same. Glad you got it figured out.
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"I am so damn glad I finally figured it out without doing it the ghetto way by just changing the PE table."
I'm glad to see you resolved your problem and please don't take this question as any type of critisism, but I don't understand why changing the MAF table is more ghetto than changing the PE table? My thinking is that the MAF table has been previously calibrated for that specific MAF sensor meaning that it provides a given freq for a given air flow. Technically, the only time we would want to change that table is if we changed that relationship, what am I missing?
I'm glad to see you resolved your problem and please don't take this question as any type of critisism, but I don't understand why changing the MAF table is more ghetto than changing the PE table? My thinking is that the MAF table has been previously calibrated for that specific MAF sensor meaning that it provides a given freq for a given air flow. Technically, the only time we would want to change that table is if we changed that relationship, what am I missing?
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Dynocar to me the maf is like ve it needs recalibrated for engine modifications pe is used to fix any slight blips in certain areas. Not that both ways dont get the job done i think this is really a whole new disscussion though.
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Original question, "What is the best way to go about getting this AF ratio down to where i want it to be?"
Ok, I'll have to start a different discussion, I must be misinterpreting the question, but I would have done it the "ghetto way".
Ok, I'll have to start a different discussion, I must be misinterpreting the question, but I would have done it the "ghetto way".
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I guess it does fit the original criteria saying you would have done it the other way, but whats is "getto" and what isnt is probbably a new disscussion maby i did the misinterpriting.
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Originally Posted by joecar
Did you log commanded AFR to see what the PCM is commanding...?
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Originally Posted by dynocar
"I am so damn glad I finally figured it out without doing it the ghetto way by just changing the PE table."
I'm glad to see you resolved your problem and please don't take this question as any type of critisism, but I don't understand why changing the MAF table is more ghetto than changing the PE table? My thinking is that the MAF table has been previously calibrated for that specific MAF sensor meaning that it provides a given freq for a given air flow. Technically, the only time we would want to change that table is if we changed that relationship, what am I missing?
I'm glad to see you resolved your problem and please don't take this question as any type of critisism, but I don't understand why changing the MAF table is more ghetto than changing the PE table? My thinking is that the MAF table has been previously calibrated for that specific MAF sensor meaning that it provides a given freq for a given air flow. Technically, the only time we would want to change that table is if we changed that relationship, what am I missing?
Last edited by brad8266; Apr 8, 2006 at 02:09 PM.
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Originally Posted by joecar
Did you log commanded AFR to see what the PCM is commanding...?
Originally Posted by brad8266
Yeah I am commanding 12.8 up to 4000 Rpms and 13.0 after that. There really isnt any logging done to see commanded afr, it is set in the pe table.
