Air/Fuel Ratio Question
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
Hey Jim, long time no talk, I hope all's well! 
I think a 224 would be a piece of cake for him if he had a '165 ECM. His biggest issues were the lack of parameters available to him in the hack. In fact, I'd venture to say he couldx probably approach a 230 duration with a more widely explored ECM and his CID.......certainly he'd be golden at 228 on a 113 LSA.
Craig FYI, there's an integrated wideband hack available in the Tunerpro '165 XDF. I have a copy if you ever need it. IIRC, it uses pin D5 in the harness
I think a 224 would be a piece of cake for him if he had a '165 ECM. His biggest issues were the lack of parameters available to him in the hack. In fact, I'd venture to say he couldx probably approach a 230 duration with a more widely explored ECM and his CID.......certainly he'd be golden at 228 on a 113 LSA.
Craig FYI, there's an integrated wideband hack available in the Tunerpro '165 XDF. I have a copy if you ever need it. IIRC, it uses pin D5 in the harness
I've been researching what it takes to convert to a 165 ECM. I need to find someone that's done it who can walk me through the steps. My background is not electrical. And I found I do a crappy job of soldering. The LC-1 wideband I installed will log AFR but it needs the Moates AutoProm. It's only money.
Race Director
Joined: Nov 2003
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From: Overland Park Kansas
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Glad you got things worked out!
What did the avg blm end up for you?
Was your wideband lambda and avg? I assume .94 means something like you're not quite to the balance point in air/fuel...with fuel being a hair richer than stoich?
If not an avg, that's where INT would make more sense for comparison...since it's the instant reading, right?
FWIW, I ended up leaving mine in the low-mid 120's. Though that would imply a bit on the safe side, my plugs look just a tiny bit lean. (Never asked if higher compression can cause that.) OTOH, my o2 bung is only allowing my 165 ecm to see two cylinders. I have 4-2-1 headers with the bung at the 1-3 pipe junction.
I considered those might be a hair leaner, but all the plugs look the same. A WB might be nice to try...just to see. The dyno showed mine at 14.7 (during low loads) so, that was another reason I called my tune "good".
I chased my tail for quite a while before I switched to a wideband sensor with a lambda gauge. Now there's no guessing on whether it's rich or lean. Case in point, at idle the BLMs indicated a lean condition while the wideband indicated .94 lambda. That one still confuses me but I'm over it.
If not an avg, that's where INT would make more sense for comparison...since it's the instant reading, right?
FWIW, I ended up leaving mine in the low-mid 120's. Though that would imply a bit on the safe side, my plugs look just a tiny bit lean. (Never asked if higher compression can cause that.) OTOH, my o2 bung is only allowing my 165 ecm to see two cylinders. I have 4-2-1 headers with the bung at the 1-3 pipe junction.
I considered those might be a hair leaner, but all the plugs look the same. A WB might be nice to try...just to see. The dyno showed mine at 14.7 (during low loads) so, that was another reason I called my tune "good".
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
Glad you got things worked out!
What did the avg blm end up for you?
Was your wideband lambda and avg? I assume .94 means something like you're not quite to the balance point in air/fuel...with fuel being a hair richer than stoich?
If not an avg, that's where INT would make more sense for comparison...since it's the instant reading, right?
FWIW, I ended up leaving mine in the low-mid 120's. Though that would imply a bit on the safe side, my plugs look just a tiny bit lean. (Never asked if higher compression can cause that.) OTOH, my o2 bung is only allowing my 165 ecm to see two cylinders. I have 4-2-1 headers with the bung at the 1-3 pipe junction.
I considered those might be a hair leaner, but all the plugs look the same. A WB might be nice to try...just to see. The dyno showed mine at 14.7 (during low loads) so, that was another reason I called my tune "good".
What did the avg blm end up for you?
Was your wideband lambda and avg? I assume .94 means something like you're not quite to the balance point in air/fuel...with fuel being a hair richer than stoich?
If not an avg, that's where INT would make more sense for comparison...since it's the instant reading, right?
FWIW, I ended up leaving mine in the low-mid 120's. Though that would imply a bit on the safe side, my plugs look just a tiny bit lean. (Never asked if higher compression can cause that.) OTOH, my o2 bung is only allowing my 165 ecm to see two cylinders. I have 4-2-1 headers with the bung at the 1-3 pipe junction.
I considered those might be a hair leaner, but all the plugs look the same. A WB might be nice to try...just to see. The dyno showed mine at 14.7 (during low loads) so, that was another reason I called my tune "good".
The wideband has a pretty fast sample rate. The slowest it can be set for is 3 times per second. I connected it to a laptop so I could view lambda and AFR simulataneously. What I found was that stoich was not 14.7. It was closer to 14.3 due to E10 gas. So if I tune such that BLMs and INTs are 128, the mixture will actually be lean. So I'll be using the wideband as the reference. By the way, I have the wideband and the stock O2 sensor installed in the same locations. Stock is on the left side and WB on the right.
Le Mans Master
Joined: Dec 2002
Posts: 5,270
Likes: 3
From: Seattle Area WA
I connected it to a laptop so I could view lambda and AFR simulataneously. What I found was that stoich was not 14.7. It was closer to 14.3 due to E10 gas. So if I tune such that BLMs and INTs are 128, the mixture will actually be lean. So I'll be using the wideband as the reference. By the way, I have the wideband and the stock O2 sensor installed in the same locations. Stock is on the left side and WB on the right.
When you say, "I found that stoich was not 14.7. It was closer to 14.3 due to E10 gas." Do you mean that you recalibrated your wideband? Or do you mean that the narrowband (BLM/INT) was happy with a value of 14.3 on your wideband, which you assume is due to running E10 gas?
The following may be redundant...
I ask because, your wideband reads lambda.
Stoich(Regular) -lambda of 1.0 = 14.7 AFR
Stoich(E10) - lambda of 1.0 = 14.13 AFR
Stoich(E85)- lambda of 1.0 = 9.76 AFR
It reads lambda - 1.0 = stoich regardless of what you tell it to convert to in AFR and regardless of the fuel used. If you calibrated your sensor for E10 then 14.13 is stoich (lambda=1), if your sensor is calibrated for regular then 14.7 AFR is stoich (lambda =1.0).
If your sensor is calibrated for regular and you run e10, 14.7 is stoich. The TRUE AFR when calibrated for regular, but running e10, is actually 14.13 when it reports 14.7 but that doesn't matter as long as you know what the calibration is, and therefore lambda.
Most come with the calibration of stoich = 14.7.
(AFR = stoich*lambda, where you update stoich based upon fuel type)
Last edited by USAsOnlyWay; May 3, 2012 at 03:50 PM. Reason: text color
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
Glad you passed smog, with later computers guys over on thirdgen have reported passing with 230/236 cams but of course they have a different computer to do it with.
When you say, "I found that stoich was not 14.7. It was closer to 14.3 due to E10 gas." Do you mean that you recalibrated your wideband? Or do you mean that the narrowband (BLM/INT) was happy with a value of 14.3 on your wideband, which you assume is due to running E10 gas?
The following may be redundant...
I ask because, your wideband reads lambda.
Stoich(Regular) -lambda of 1.0 = 14.7 AFR
Stoich(E10) - lambda of 1.0 = 14.13 AFR
Stoich(E85)- lambda of 1.0 = 9.76 AFR
It reads lambda - 1.0 = stoich regardless of what you tell it to convert to in AFR and regardless of the fuel used. If you calibrated your sensor for E10 then 14.13 is stoich (lambda=1), if your sensor is calibrated for regular then 14.7 AFR is stoich (lambda =1.0).
If your sensor is calibrated for regular and you run e10, 14.7 is stoich. The TRUE AFR when calibrated for regular, but running e10, is actually 14.13 when it reports 14.7 but that doesn't matter as long as you know what the calibration is, and therefore lambda.
Most come with the calibration of stoich = 14.7.
(AFR = stoich*lambda, where you update stoich based upon fuel type)
When you say, "I found that stoich was not 14.7. It was closer to 14.3 due to E10 gas." Do you mean that you recalibrated your wideband? Or do you mean that the narrowband (BLM/INT) was happy with a value of 14.3 on your wideband, which you assume is due to running E10 gas?
The following may be redundant...
I ask because, your wideband reads lambda.
Stoich(Regular) -lambda of 1.0 = 14.7 AFR
Stoich(E10) - lambda of 1.0 = 14.13 AFR
Stoich(E85)- lambda of 1.0 = 9.76 AFR
It reads lambda - 1.0 = stoich regardless of what you tell it to convert to in AFR and regardless of the fuel used. If you calibrated your sensor for E10 then 14.13 is stoich (lambda=1), if your sensor is calibrated for regular then 14.7 AFR is stoich (lambda =1.0).
If your sensor is calibrated for regular and you run e10, 14.7 is stoich. The TRUE AFR when calibrated for regular, but running e10, is actually 14.13 when it reports 14.7 but that doesn't matter as long as you know what the calibration is, and therefore lambda.
Most come with the calibration of stoich = 14.7.
(AFR = stoich*lambda, where you update stoich based upon fuel type)
This is why I intend to do the performance tune based on lambda.
Le Mans Master
Joined: Dec 2002
Posts: 5,270
Likes: 3
From: Seattle Area WA
I think we're saying the same thing. I believe what I found is that the true stoich for the gas I'm running is approx 14.3 AFR. I don't know if the gas is true E10. And 14.13 vs 14.3 is a little hard to determine when the gauge is not that steady. The importance to me is that I think the ECM is calibrated for a stoich of 14.7. If I tune to achieve 128 BLMs, isn't the mixture actually going to be lean?
This is why I intend to do the performance tune based on lambda.
This is why I intend to do the performance tune based on lambda.
For performance, since I know the calibration is set at lambda of 1.0=14.7, I just plug in the numbers (desired lambda of ~0.86 at WOT) and know if I get 12.6-12.9 I'll be pretty good, regardless of the fuel used.
Last edited by USAsOnlyWay; May 3, 2012 at 04:50 PM.
