Help. Rich condition
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Staging Lane
Joined: Sep 2012
Posts: 71
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From: Stringer ms
Help. Rich condition What could cause a tuned car to go rich it at a specific RPM. My car is completely tuned and will go from 12.5 fuel ratio to 10.4 at 5200 RPM exactly every time. Close loop or open loop, neither one changes it. When we log yet, nothing else changes, the fuel pressure the time in the voltage nothing changes but the air fuel ratio at 5200. Any ideas
If this is a stock truck ecm this could be a power enrichment issue. On the truck platforms PE mode is delayed till 5500rpm. This is just a possibilitie.
One thing u can try but be careful with is turn off PE mode and command 14.7 and see if it does the same
One thing u can try but be careful with is turn off PE mode and command 14.7 and see if it does the same
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Staging Lane
Joined: Sep 2012
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From: Stringer ms
TECH Fanatic
Joined: Oct 2014
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From: Virginia
Well that's pretty weird. I'm also leaning (har har) towards PE possibly causing this.
Is this on pump gas? The 12.5 AFR is pretty damn rich already for part throttle.
What does the commanded say in the scanner? Does it match the AFR?
Is this on pump gas? The 12.5 AFR is pretty damn rich already for part throttle.
What does the commanded say in the scanner? Does it match the AFR?
Thread Starter
Staging Lane
Joined: Sep 2012
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From: Stringer ms
im sorry, this is at full throttle. Command is 12.7 at full throttle.
TECH Fanatic
Joined: Oct 2014
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From: Virginia
What u are commanding and actually getting are 2 diff things. U can be commanding 12.5 but if the maf/VE is off u want get tht. It could be leaner or richer. Most tuners rape the pe table to get the commanded afr they want. Thts not the correct way. Tune the ve and maf and things fall into place!
TECH Fanatic
Joined: Oct 2014
Posts: 1,220
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From: Virginia
What u are commanding and actually getting are 2 diff things. U can be commanding 12.5 but if the maf/VE is off u want get tht. It could be leaner or richer. Most tuners rape the pe table to get the commanded afr they want. Thts not the correct way. Tune the ve and maf and things fall into place!
PE should climb up to the target fairly quickly, and STAY at your target to the end of the table. 12.5 is the typical target for N/A. BE is 11.5 (boost).
A value of 1.17 will get you 12.5 if your stoich is 14.63.
TECH Fanatic
Joined: Oct 2014
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From: Virginia
Are you actually changing the tune? Or are you just throwing tunes at it? It's starting to make me wonder if there is any actual tuning going on here. I am assuming you are using a WB, since you know the AFR.
What you should be doing is logging WB and commanded AFR, then making a histo that plots the error on either your VE (MAP vs RPM) or MAF (hertz). Normally VE is tuned with MAF disabled. MAF is then tuned if not staying strictly speed density.
What you should be doing is logging WB and commanded AFR, then making a histo that plots the error on either your VE (MAP vs RPM) or MAF (hertz). Normally VE is tuned with MAF disabled. MAF is then tuned if not staying strictly speed density.
Teching In
Joined: Feb 2018
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From: Billings, MT
You are going to get a lot better answers if you post the tune you are using and a log of the issue. Be sure to log channels like commanded AFR and actual AFR. Everyone can speculate on what the problem is based on what you are describing but posting a log and tune will help much more. A picture is worth a thousand words.
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Joined: Oct 2014
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From: Virginia
Agreed. Post a log and tune, and we can figure this out for you. Not sure what my word count is on this thread so far, but a picture really is worth at least a thousand words. A log or tune is worth even more...