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Old 03-06-2006, 11:09 PM   #1
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Default PCM Learning related to pulley swap

So just how long does it take the PCM to learn from a pulley swap

If it takes, as I see from some members posts, a few hundred miles, then swapping pulley'* at the track would be kind of useless.

I have been running since the summer with a 3.2 pulley. I ran all summer with a 3.1 including at the WCB Meet. I downsized to see if it would make any difference.
I have just installed a 3.0 pulley but honestly can't notice much difference with the boost gauge or seat of the pants between any of these sizes. WTF
I always use 94 Octane and the engine is always < 160 F.

I am not using the water/meth injection yet either. Saving that for warmer temps.

Ya, I know, scan, scan, scan.
Using the AutoTap is a real pain and lately I haven't had the car on the road long enough to really play with tuning.

Just wondering what Rogue and others opinions are based on my mods. Is it best to pick a pulley and then stick with it? Is a 3.0 pulley pushing the envelope?
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Old 03-06-2006, 11:20 PM   #2
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Paul, I wish I was more familiar with the OBD2 PCM'*, but I can tell you it takes time with the OBD1. And I'd agree with you at this point that changing at the track is pointless. I firmly believe you need to change it a week before and start running the octane you're going to at LEAST 50 miles before you get to the track, using heavy throttle to teach the sucker what you're about to do.

The other thing to consider is that each tenth of an inch you drop gains you less than the tenth before. So you may have only added 5-10hp for the drop from 3.2-3.0.

Ultimately, we're going to need the INTENSE or ZZP Guru'* in on this one.
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Old 03-06-2006, 11:47 PM   #3
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Good question. I read it only takes 30 mins for the pcm to learn the fuel tables. My guess is thats all that would be needed for a pulley swap.
The power tuner guys usually have two programs, 1 for street and 1 for strip and upload at the track along with a pulley swap.

Come to mention it did I swap at the campground or at the track last year? I think it was the campground? or was it Bill'*?
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Old 03-06-2006, 11:50 PM   #4
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It took my car 2 miles last Apri for the 3.5". If only it would do it for the rockers.
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Old 03-07-2006, 12:07 AM   #5
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Quote:
Originally Posted by fantastic88
It took my car 2 miles last Apri for the 3.5". If only it would do it for the rockers.
And you know it took 2 miles how?
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Old 03-07-2006, 12:10 AM   #6
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Quote:
And you know it took 2 miles how?
Nate'* scan tool for timing. Which I may use tomarow for the rockers so PD can see the results.
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Old 03-07-2006, 01:14 AM   #7
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You need to look at LT and ST fuel trims, O2 toggle, timing, AFR, and all sorts and bunches of crap to see when things settle. There'* no way to know if something has 'learned' within 2 miles.
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Old 03-07-2006, 01:18 AM   #8
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Yup, I have lots to learn about tuning. I thought the rockers would be plug and chug like the mild 3.5" pulley. Boy was I wrong. Hopefully i'll be able to get some info tomarrow.
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Old 03-07-2006, 08:31 AM   #9
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You may be able to force learn it by killing power to the car for 30 min.

If it needs to relearn idle..then why can't we use that same thing to force a learn on the pulley size?
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Old 03-07-2006, 09:17 AM   #10
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Quote:
Originally Posted by BillBoost37
You may be able to force learn it by killing power to the car for 30 min.

If it needs to relearn idle..then why can't we use that same thing to force a learn on the pulley size?
Because it MIGHT default to the stock fuel curves. And it'll have to re-learn anyway. Relearning idle after a PCM power down only takes 3 cycles of the IAC.
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