Rockers installed, computer learning issue? (PROBLEM SOLVED) - Page 3 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 06-28-2006, 05:01 AM   #21
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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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Old 06-28-2006, 12:16 PM   #22
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Quote:
Originally Posted by chadow427
So does that mean the computer needs more time at WOT to re-learn how much fuel is needed?
If you've done 200 miles and a couple of driving cycles then the learning is done. The PCM'* learning capacity is only done under limited conditions, it doesn't mean to say the PCM will ever be able to adjust in an optimal fassion for the rockers.

How'* that scan coming along

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Old 06-28-2006, 01:44 PM   #23
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I'm almost certain its valve float. I had the same situation when I first put my 1.9'* on and that was with 35k miles on the car. We thought for the longest time it was a rev limiter issue (PCM'* were just coming out back then) but put springs on the car and it went away. You can get KR from being to rich as well as to lean and if the valves are not closing all the way this can really mess up the 02s reading.
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Old 06-28-2006, 02:38 PM   #24
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After having done his rockers 3 times already and with other problems showing up, I wouldn't be in a rush to swap springs before knowing more about what'* going.

While you can have KR from overly rich mixtures, it'* unlikely in this case as he was not having this problem before installing the rockers, not to mention he'* more likely to be lean after having increased the airflow.

The rev limiter for a 2000 SSEi is set at 5950 RPM for the high limit.

While we can't rule out valve float, it'* speculation to say what'* going on without seeing a scan first. Still, with 14* of KR you had a maximum of 2.5* of timing advance at 5700 RPM...care to guess how gutless the car would feel with so little timing?

Let see a scan

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Old 06-28-2006, 04:20 PM   #25
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I can do a visual scan with the aeroforce, but I can't record with it. Should I scan for STFT or LTFT? I've got the two "screens" and can record for a little bit, but I don't know what to look for.
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Old 06-28-2006, 05:31 PM   #26
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I would scan 02 MV and Timing.

If they dont drop immediately to 0 and then bounce (rev limiter) but they do bounce up and down when its happening its probably valve float.
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Old 06-28-2006, 11:36 PM   #27
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I'll just toss the springs on this week, see what happens and then I'll know if I have a problem.
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Old 07-08-2006, 05:19 AM   #28
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Problem solved. It must have been valve float, because I put the springs on today and it revs freely all the way to redline. It also killed all my KR with the 3.4. Now to drop down to the 3.2 or even 3.0 (on race gas) .
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Old 07-08-2006, 10:53 AM   #29
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Glad you got it figured out
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