Lean cruise
Thread Starter
Joined: Sep 2004
Posts: 4,904
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From: Stockbridge GA
Lean cruise So I decided to play with lean cruise a bit in my GTO again. I did it years ago and found it was not worth it, but I got bored. The factory Aussie tunes have spots that go as lean as 17.8/1, but that gives a lot of lean misfires on the GTO. Long story short, after putting in values to equal about 16.3/1 in several cells, the computer glitched on me and started commanding exactly 32/1 while I was driving down the interstate. It did not quit below 47mph, either, as it was supposed to. It only returned to 14.68/1 after I pulled over to 0mph. After that, it ran fine. No idea what may have caused this glitch, but I am going back to my previous idea that lean cruise is not worth messing with.
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Joined: Dec 2004
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From: Florida
I never had that glitch happen but I’ve never had much luck with the way it’s implemented either.
what worked best for me was the efilive cos5 run in open loop. At cruise rpm and map values I could pull fuel and add timing without affecting other areas and it was baked into the tables instead of using some sort of conditional logic.
what worked best for me was the efilive cos5 run in open loop. At cruise rpm and map values I could pull fuel and add timing without affecting other areas and it was baked into the tables instead of using some sort of conditional logic.
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Joined: Sep 2019
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If you lean out your cruise until you start to get missfires you will get better MPG but I seriously doubt that it was truly running at 32:1. I would expect that the O2 sensor started to read its max voltage and lost its ****. 32:1 will not light with a spark.
Some engines can run as lean as 18:1 in the cruise but you may well have to play with it. It's also dependent on things like engine size, cruise RPM, compression, heat, all that good stuff.
Some engines can run as lean as 18:1 in the cruise but you may well have to play with it. It's also dependent on things like engine size, cruise RPM, compression, heat, all that good stuff.
Thread Starter
Joined: Sep 2004
Posts: 4,904
Likes: 906
From: Stockbridge GA
If you lean out your cruise until you start to get missfires you will get better MPG but I seriously doubt that it was truly running at 32:1. I would expect that the O2 sensor started to read its max voltage and lost its ****. 32:1 will not light with a spark.
Some engines can run as lean as 18:1 in the cruise but you may well have to play with it. It's also dependent on things like engine size, cruise RPM, compression, heat, all that good stuff.
Some engines can run as lean as 18:1 in the cruise but you may well have to play with it. It's also dependent on things like engine size, cruise RPM, compression, heat, all that good stuff.
Thread Starter
Joined: Sep 2004
Posts: 4,904
Likes: 906
From: Stockbridge GA
I changed the tune without saving it, but here is the log from that fun little ride. Don't mind the screwed up fuel trims, I had just re-enabled the maf and had not finished tuning for it.
I've been running Lean Cruise in my GTO since late '04/early '05. The factory Holden settings were way too lean for my liking. I used to run up to 16:1 with the stock cam and LPE GT2-3 cam. Got a best of 33mpg on a tank of gas with 30mpg the norm. After changing to hotter cams, I had to go richer. Usually 15.5:1 or so. Upper 15's will start surging but not throw any misfire codes. So I'm fairly conservative these days on it. I could probably really play with like I used to, but I just like driving it the way it is. Its nice and smooth and still seemless when it engages.
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I've been running Lean Cruise in my GTO since late '04/early '05. The factory Holden settings were way too lean for my liking. I used to run up to 16:1 with the stock cam and LPE GT2-3 cam. Got a best of 33mpg on a tank of gas with 30mpg the norm. After changing to hotter cams, I had to go richer. Usually 15.5:1 or so. Upper 15's will start surging but not throw any misfire codes. So I'm fairly conservative these days on it. I could probably really play with like I used to, but I just like driving it the way it is. Its nice and smooth and still seemless when it engages.
I have always been under the impression, that was not available in the US because it drives the NOX gasses through the roof when this happens and it was prohibited.
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Verdad Gallardo Thread Starter
Joined: Sep 2004
Posts: 4,904
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From: Stockbridge GA
So the factory GTO allows you, or has lean cruise enabled on them in the US? Your not going in and doing a SD lean cruise-ish setup, but a fully enabled version in the US?
I have always been under the impression, that was not available in the US because it drives the NOX gasses through the roof when this happens and it was prohibited.
I have always been under the impression, that was not available in the US because it drives the NOX gasses through the roof when this happens and it was prohibited.
So the factory GTO allows you, or has lean cruise enabled on them in the US? Your not going in and doing a SD lean cruise-ish setup, but a fully enabled version in the US?
I have always been under the impression, that was not available in the US because it drives the NOX gasses through the roof when this happens and it was prohibited.
I have always been under the impression, that was not available in the US because it drives the NOX gasses through the roof when this happens and it was prohibited.
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Joined: Oct 2006
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From: Euless, TX
Last edited by Fast355; Jul 5, 2023 at 08:33 AM.