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Old 01-10-2008, 03:06 AM   #1
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Default General Target AFR's and Lean Cruise

Ok, I was about to run through an auto-tune, when I looked at the table and thought it was WAY too rich. My goodness, 12.8:1 while still NA? And the cruising (like 60-80 mph) is still 13.0 or so.

Well, I bumped all the lower rows (more vacuum) a bit leaner. Maybe it's a bad idea, but it'll still be richer than I have it.

I found this:

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Under cruise conditions, the VN-VPs cruise on 14.7:1, while VRs onward use a lean cruise function. Lean cruise kicks in once coolant temperature is over 80 degrees C, you're travelling faster than 68 km/h, the engine is spinning at between 1600 and 2800 rpm and manifold vacuum is between 40 kPa and 60 kPa absolute (the VS-on works on an airflow meter signal). Once 150 seconds is timed out under those conditions, the air-fuel ratio will lean out one point every 0.15 seconds. They're set up to run as lean as 16.5:1 - but only at that light load cruise situation. You can't be driving on and off the throttle.
BTW, how do I tell if my innovative is calibrated right? Can I just turn on the car without running the motor for a few minutes and see if it says 14.7, or do I need to pull it out of the pipe, etc?
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Old 01-10-2008, 03:37 AM   #2
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my lc1 with the key on no engine running says like 22.4 cuz 14.7 the motor would have to be on to read that! and being turbo i cruise about 14.5-15 so being na that isnt a bad idea pulling the wideband outta the pipe is just for calibration with just key on it should just read no fuel just oxygen which mine shows 22.4 when the car has been off for at least 30 mins
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Old 01-10-2008, 08:44 AM   #3
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Originally Posted by AbeFM View Post
Ok, I was about to run through an auto-tune, when I looked at the table and thought it was WAY too rich. My goodness, 12.8:1 while still NA? And the cruising (like 60-80 mph) is still 13.0 or so.

Well, I bumped all the lower rows (more vacuum) a bit leaner. Maybe it's a bad idea, but it'll still be richer than I have it.
I aim for 15.5 - 16.5 at cruise you've got a lot more scope for leaning out

basically hit the highway laptop on the passeneger seat and press 'G' when in the tuning window so your cursor follows the green blob, hold a steady state cruise and lean out until the car starts to 'surge' then richen up till it stops.

for timing bump it up until it starts to surge again, and then adjust the fuelling to suit. rinse repeat. Off the top of my heat my cruise portion of my ign_adv is around 35 BTDC

tuned for economy when cruising now

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BTW, how do I tell if my innovative is calibrated right? Can I just turn on the car without running the motor for a few minutes and see if it says 14.7, or do I need to pull it out of the pipe, etc?
load up logworks and look at the guage in that, it it matches what MT says it's calibrated correctly in MT. (I looked at what it was idling at and then swopped connections, but if you've got 2 laptops it'd be better/easier).
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Old 01-10-2008, 09:14 AM   #4
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How did you come across some bogun website telling you how commodores run? If you don't know what they are they are like ****** down here in aus, cheap and every ****** has one.

I'm sure you could cruise a bit leaner though. As for 12.8, I have done a bit of reading and thats is quite an acceptable targetr for full load hight rpm. The mspnp faq is quite helpful for afrs I find also.
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Old 01-10-2008, 06:48 PM   #5
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Quote:
Originally Posted by richyvrlimited View Post
I aim for 15.5 - 16.5 at cruise you've got a lot more scope for leaning out

basically hit the highway laptop on the passeneger seat and press 'G' when in the tuning window so your cursor follows the green blob, hold a steady state cruise and lean out until the car starts to 'surge' then richen up till it stops.

for timing bump it up until it starts to surge again, and then adjust the fuelling to suit. rinse repeat. Off the top of my heat my cruise portion of my ign_adv is around 35 BTDC
That may be the single most useful thing I have ever read on tuning *EVER*. Congratulations on the best post of all time.

Nothing like simple directions with a step by step. So when adding more fuel doesn't fix the surge caused by the timing, back it off and you're done?

Quote:
Originally Posted by richyvrlimited View Post
load up logworks and look at the guage in that, it it matches what MT says it's calibrated correctly in MT. (I looked at what it was idling at and then swopped connections, but if you've got 2 laptops it'd be better/easier).
Oh, too bad. So much for that best post thing. It's more an open air calibration. The quick start guide said something about pressing a button and the light should flash, and it didn't really make sense. Then I got in the car and the numbers are... believable, but I'm not really sure they are right.



As a total aside, someone have good info for the thermo on a 2000? My values are a bit off. A tweaked one and generated a curve, but I'm sure it's off.
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Old 01-10-2008, 06:53 PM   #6
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this is what i generally try to achieve:

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