Rockers installed, computer learning issue? (PROBLEM SOLVED) - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 06-25-2006, 10:17 PM   #11
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I got LUCKY not having valve float, even with modified stock rockers because of my mileage. But with rollars its almost guarenteed even with a newer low mileage engine. Then again I do have stock shift points. When I get a DHP with 6K shifts, that may tell another story. Hopefully not though *knocks on wood*
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Old 06-26-2006, 12:45 AM   #12
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Just got back from another spin, I've put about 130 miles on it since the swap, the high end bog has gotten a little better, but not much. I'll just put the springs in and that should solve it.....here goes another rocker swap....if anybody needs help I've gotten it down to a couple hours...
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Old 06-27-2006, 02:42 AM   #13
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What'* the ratio of your new rockers? :o
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Old 06-27-2006, 05:28 PM   #14
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1.9'*...
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Old 06-27-2006, 07:06 PM   #15
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You've done it three times now? Twice at my house, once at yours? Going for #4?

Good thing you bought that spring compressor. Now you need to get that air chuck/spark plug adapter rigged up.
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Old 06-27-2006, 09:12 PM   #16
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Have you scanned again now you've put more miles on it? Can you post a scan so we can look at it?

You mentioned 14* KR in your first post, that can certainly make the car feel very flat and powerless. The KR you're getting is likely the result of the increased airflow seen by the MAF now you have higher ratio rockers. It'* unlikely your Long Term Fuel Trims (LTFT) are locking in close to zero when in Power Enrichment (PE) mode. The result is lean fuel mixtures, detonation and then Knock Retard (KR).

I've seen lots of SII L6s with rockers do fine on stock springs. I don't think that'* where your trouble lies. Do some more scanning to see your engine status...14* of timing retard by way of KR will kill your performance altogether. You might be walking into further problems.

Scan, scan, scan...it'* the only way to know what'* going on.

Cheers,
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Old 06-27-2006, 11:22 PM   #17
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I agree with foghorn, the springs are not causing 14* of kr.
There is something else going on, what kind of scanner do you have?
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Old 06-28-2006, 12:29 AM   #18
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A lean mixture (if not too severe) may be resolved with an adjustable FPR.

FALSE KR may be an issue if there'* excessive valvetrain noise. Does it sound louder? Clickety clackity?
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Old 06-28-2006, 01:38 AM   #19
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The slight ticking will not set off false knock.

If anything the lower pressure drop caused by opening the valves will lower the boost pressure and should reduce heating effect thus improving knock resistance.

I only had this limiter feeling type problem when I actually increased air flow by going to a smaller pulley.
When I swapped to the rockers I did not have this problem but then I did also do the springs and increased the fuel flow using the pressure regulator.
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Old 06-28-2006, 05:00 AM   #20
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It has reduced in severity, but still feels like its tapping the rev limiter at about 5700. I don't have an actual scanner, just an aeroforce interceptor gauge.

-Foghorn "You mentioned 14* KR in your first post, that can certainly make the car feel very flat and powerless. The KR you're getting is likely the result of the increased airflow seen by the MAF now you have higher ratio rockers. It'* unlikely your Long Term Fuel Trims (LTFT) are locking in close to zero when in Power Enrichment (PE) mode. The result is lean fuel mixtures, detonation and then Knock Retard (KR)."

So does that mean the computer needs more time at WOT to re-learn how much fuel is needed? I can do that. That was my initial impression, but then I thought it was springs.....now I don't know. Do the rockers increase the airflow enough that the computer would need a decent amount of time to relearn the fueling?
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