Use of O2 R/L tables in 6E MAF systems
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Use of O2 R/L tables in 6E MAF systems
After re-reading the stickies on the 730 O2 constants and RBob's ECM Proportional Control from '02 (awesome write up dude!) I am still plagued by a delima on my 6E MAF system.
To bring you up to speed here...
You can look at my sig but it's an aluminum headed L98 with a mild cam (212/218) HSR intake etc. I am using TunerPro v5 and have an Innovate WBO2 gauge with the WB output in my data logs. I am working with the expectation that my WB readings are correct at idle. Stoich AFR is set @ 14.7 and I am running 10% alcohol fuel. I have been adjusting my O2 R/L mean, upper and lower tables to bring my idle AFR to ~14.7 to 15. Currently my mean O2 R/L is 635 at idle with upper/lower +/-35. 14.7 on the WB gauge is where my engine pulls the most vacuum @ 16hg. Idle speed is 650. I have been able to get the idle AFR perfect when up to full temp and BLM's are 128ish. After idling for about 4-5 minutes the BLM's start to drop to 118 and AFR jumps up to <16. It seems to stablize there but vac drops to 15hg and it runs less smoothly.
My question is "Why does the ecm start pulling fuel after idling for a while?" I suspect it is somewhere in my other settings like the reduction gains or filters but can't seem to get a handle on it. My gut call is that something is getting into a runaway situation mathmatically. Any suggestions on what to adjust will be greatly appreciated.
BTW I have deleted my EGR and AIR and have made the necessary changes in the bin.
To bring you up to speed here...
You can look at my sig but it's an aluminum headed L98 with a mild cam (212/218) HSR intake etc. I am using TunerPro v5 and have an Innovate WBO2 gauge with the WB output in my data logs. I am working with the expectation that my WB readings are correct at idle. Stoich AFR is set @ 14.7 and I am running 10% alcohol fuel. I have been adjusting my O2 R/L mean, upper and lower tables to bring my idle AFR to ~14.7 to 15. Currently my mean O2 R/L is 635 at idle with upper/lower +/-35. 14.7 on the WB gauge is where my engine pulls the most vacuum @ 16hg. Idle speed is 650. I have been able to get the idle AFR perfect when up to full temp and BLM's are 128ish. After idling for about 4-5 minutes the BLM's start to drop to 118 and AFR jumps up to <16. It seems to stablize there but vac drops to 15hg and it runs less smoothly.
My question is "Why does the ecm start pulling fuel after idling for a while?" I suspect it is somewhere in my other settings like the reduction gains or filters but can't seem to get a handle on it. My gut call is that something is getting into a runaway situation mathmatically. Any suggestions on what to adjust will be greatly appreciated.
BTW I have deleted my EGR and AIR and have made the necessary changes in the bin.
Last edited by antman89iroc; 09-21-2012 at 10:10 PM.
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Re: Use of O2 R/L tables in 6E MAF systems
Check the O2 signal, that is what the ECM will follow. I like to graph it along with RPM to get a better idea of what it is doing.
When an O2 sensor cools off it tends to report lean, which forces the BLM high. A silicone poisoned sensor reports rich driving the BLM down.
With the headers need to use a heated O2 sensor. If the tip of the sensor has a white almost fluffy substance on it that is silicone.
RBob.
When an O2 sensor cools off it tends to report lean, which forces the BLM high. A silicone poisoned sensor reports rich driving the BLM down.
With the headers need to use a heated O2 sensor. If the tip of the sensor has a white almost fluffy substance on it that is silicone.
RBob.
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Re: Use of O2 R/L tables in 6E MAF systems
Check the O2 signal, that is what the ECM will follow. I like to graph it along with RPM to get a better idea of what it is doing.
When an O2 sensor cools off it tends to report lean, which forces the BLM high. A silicone poisoned sensor reports rich driving the BLM down.
With the headers need to use a heated O2 sensor. If the tip of the sensor has a white almost fluffy substance on it that is silicone.
RBob.
When an O2 sensor cools off it tends to report lean, which forces the BLM high. A silicone poisoned sensor reports rich driving the BLM down.
With the headers need to use a heated O2 sensor. If the tip of the sensor has a white almost fluffy substance on it that is silicone.
RBob.
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Re: Use of O2 R/L tables in 6E MAF systems
Antman,
ever figure out what was the problem here?
ever figure out what was the problem here?
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Re: Use of O2 R/L tables in 6E MAF systems
Not really, I ended up building a different motor and running the EBL flash ecm. Now with a longer duration cam (and larger ci) I still have had a difficult time with closed loop. I run open loop during idle and closed loop at cruise with the PID dummed down some. I also bracket the BLM so it can't adjust farther than 120/136, which it does stay between. Don't know if that helps but it's what I've done.
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