AFR Goes Lean .... Sometimes.
Thread Starter
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 232
From: SoCal
AFR Goes Lean .... Sometimes.
I need some help.....
During the last ten days my car is running perfect AFR one day and the next it is extreamly lean. The tune is not being changed. I have a WB. When it is lean (over 14.0 it is pinging) so I believe the WB is accurate and something is allowing air in .... but not every day. I have cleaned the MAF and turned the airpump off. I also put the car in SD to confirm its not the MAF signal.
Would someone like to offer some possibilities and how to check for them.
Thanks,
DH
During the last ten days my car is running perfect AFR one day and the next it is extreamly lean. The tune is not being changed. I have a WB. When it is lean (over 14.0 it is pinging) so I believe the WB is accurate and something is allowing air in .... but not every day. I have cleaned the MAF and turned the airpump off. I also put the car in SD to confirm its not the MAF signal.
Would someone like to offer some possibilities and how to check for them.
Thanks,
DH
Race Director
Joined: May 2005
Posts: 15,960
Likes: 21
From: West Norriton PA
St. Jude Donor '08
I need some help.....
During the last ten days my car is running perfect AFR one day and the next it is extreamly lean. The tune is not being changed. I have a WB. When it is lean (over 14.0 it is pinging) so I believe the WB is accurate and something is allowing air in .... but not every day. I have cleaned the MAF and turned the airpump off. I also put the car in SD to confirm its not the MAF signal.
Would someone like to offer some possibilities and how to check for them.
Thanks,
DH
During the last ten days my car is running perfect AFR one day and the next it is extreamly lean. The tune is not being changed. I have a WB. When it is lean (over 14.0 it is pinging) so I believe the WB is accurate and something is allowing air in .... but not every day. I have cleaned the MAF and turned the airpump off. I also put the car in SD to confirm its not the MAF signal.
Would someone like to offer some possibilities and how to check for them.
Thanks,
DH
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Check your O2 sensor output readings. See if they look normal when the problem occurs.
Some other things that can effect A/F ratio are:
Intake Air Temp sensor
Map sensor
Coolant temp sensor
Use a scaner and watch all of those values to see it one is providing erratic readings or going open or shorted.
I have EFI Live and can make a PID file to monitor what ever sensors that I choose. See if you can find someone with EFI Live, HP Tuners ect and maybe that can help you figure it out.
BC
Some other things that can effect A/F ratio are:
Intake Air Temp sensor
Map sensor
Coolant temp sensor
Use a scaner and watch all of those values to see it one is providing erratic readings or going open or shorted.
I have EFI Live and can make a PID file to monitor what ever sensors that I choose. See if you can find someone with EFI Live, HP Tuners ect and maybe that can help you figure it out.
BC
Le Mans Master
Joined: Dec 2000
Posts: 7,096
Likes: 153
From: "Atlanta" Ga.
OK, this is a really dumb question, but where are you getting your AFR number from ????
I know that if it is not being read correctly, you will get incorrect results. This happened to me when I was having my Z dynotuned. Long story short, my guess is to first verify the AFR reading are correct and that is indeed what is causing the pinging.
Disclaimer: all I know about cars is what I learned on CF, from other guys like me
I know that if it is not being read correctly, you will get incorrect results. This happened to me when I was having my Z dynotuned. Long story short, my guess is to first verify the AFR reading are correct and that is indeed what is causing the pinging.
Disclaimer: all I know about cars is what I learned on CF, from other guys like me
Thread Starter
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 232
From: SoCal
Thread Starter
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 232
From: SoCal
Check your O2 sensor output readings. See if they look normal when the problem occurs.
Some other things that can effect A/F ratio are:
Intake Air Temp sensor
Map sensor
Coolant temp sensor
Use a scaner and watch all of those values to see it one is providing erratic readings or going open or shorted.
I have EFI Live and can make a PID file to monitor what ever sensors that I choose. See if you can find someone with EFI Live, HP Tuners ect and maybe that can help you figure it out.
BC
Some other things that can effect A/F ratio are:
Intake Air Temp sensor
Map sensor
Coolant temp sensor
Use a scaner and watch all of those values to see it one is providing erratic readings or going open or shorted.
I have EFI Live and can make a PID file to monitor what ever sensors that I choose. See if you can find someone with EFI Live, HP Tuners ect and maybe that can help you figure it out.
BC
My IAT seems to be reading ambient temps as usual
I have HPTuner and I can look at all these parameters. So I will try to see if one looks odd. I'm just not good enough to maybe tell.
I am going to block off the end of my A.I.R system. If the check valve in there is getting stuck this will be easy to remove from the possible list.
Thanks,
DH
Melting Slicks
Joined: Apr 2003
Posts: 2,285
Likes: 16
From: Nashville TN
I had a similar problem. One bank would go lean occasionaly. I checked everything, I was ready to pull my hair out, then I replaced the O2 sensor. That fixed my problem. So check your O2s.
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Thread Starter
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 232
From: SoCal
Thread Starter
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 232
From: SoCal
Anything is possible...good thoughts
The injectors are brand new.
The fuel pump is a little older.......109K mile
But it has not been a gradual problem. AFR was dead on one day and then extreamly lean the very next.
DH