lean condition problems
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New User
Joined: Sep 2003
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lean condition problems
My I-6 300 is running lean. I changed plugs the other day and they were white. I'm chasing the cause for the lean condition but
my question is..is it hurting anything to run lean? It may take awhile before I get to fixing it and I didn't want to let it go too long if it is going to cause problems. Also, I'm checking for intake leaks, vacuum leaks, EGR problems etc. Any advice for what to check for the cause of the lean condition.
Thanks in advance
my question is..is it hurting anything to run lean? It may take awhile before I get to fixing it and I didn't want to let it go too long if it is going to cause problems. Also, I'm checking for intake leaks, vacuum leaks, EGR problems etc. Any advice for what to check for the cause of the lean condition.
Thanks in advance
Post Fiend
Joined: Jun 2001
Posts: 5,228
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From: Running Springs CA
If it is EFI, it is supposed to run lean. I have found white plugs normal in EFI engines running unleaded fuel. If there is no pinging, backfiring or check engine light, there is nothing wrong.
EFI is calibrated at idle and cruise to run lean of a perfect air-fuel ratio, rich only at or near wide open throttle. There is actually less waste heat a lean-of-peak condition. If you had an exhaust gas temperaure gauge, you would see it. I know this is a difficult concept for us old-timers who used to jet carbs on the rich side, thinking that we were helping the engines last longer. All it really did was contaminate the oil and pollute the air.
EFI is calibrated at idle and cruise to run lean of a perfect air-fuel ratio, rich only at or near wide open throttle. There is actually less waste heat a lean-of-peak condition. If you had an exhaust gas temperaure gauge, you would see it. I know this is a difficult concept for us old-timers who used to jet carbs on the rich side, thinking that we were helping the engines last longer. All it really did was contaminate the oil and pollute the air.
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Joined: Sep 2003
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My truck is a 1991 with EFI. It had some pinging under light load with a little throttle. That is why I changed the plugs, to see if it made a difference. It definately reduced the pinging to the point where it is tough to hear. The check engine light is on and I did a quick check on codes the other week when I had some time but haven't had any time since to dig deeper into it. Some of the codes were EGR related but I haven't checked for specifics.
