Power drop after 4000rpm
11-27-2007, 01:58 PM
#1
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Power drop after 4000rpm
Has anybody got any ideas why my power would be dropping off so soon on an 05 Avalanche 5.3l ,sts turbo 60-1 ,fmic ,sd tune ,comp cam 220 ,115lsa ,2500 stall.
Is this perhaps the new comp cam or am I out of turbo?
Is this perhaps the new comp cam or am I out of turbo?
11-27-2007, 02:05 PM
#2
Could it be that your running out of MAF? I think the stock MAF setting is set to take over around 4000rpm... Or you MAF is not calibrated correctly??
Originally Posted by EFI Live description for B0120
If engine speed is less than this value, then the PCM uses a dynamically calculated airflow value to determine grams of air per cylinder.
While the airflow is in a "steady state", then a correction factor is updated based on the airflow difference between the MAF sensed airflow and the MAP calculated airflow.
During rapid changes in airflow, the correction factor is applied to the airflow calculations to compensate.
If engine speed is above this value, then the PCM will use the MAF sensor exclusively (if not disabled by DTCs) to calculate grams of air per cylinder.
No updates are made to the airflow correction factor.
While the airflow is in a "steady state", then a correction factor is updated based on the airflow difference between the MAF sensed airflow and the MAP calculated airflow.
During rapid changes in airflow, the correction factor is applied to the airflow calculations to compensate.
If engine speed is above this value, then the PCM will use the MAF sensor exclusively (if not disabled by DTCs) to calculate grams of air per cylinder.
No updates are made to the airflow correction factor.
11-27-2007, 07:54 PM
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if it feels like it hits a wall and looses power you need more fuel!!!!!!
quick fix.... up your fuel pressure 10lbs and see if it gets better, if so you need more fuel.
quick fix.... up your fuel pressure 10lbs and see if it gets better, if so you need more fuel.
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11-27-2007, 09:28 PM
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Yup I upgraded to the Walbro and I'm running 46 lbers ,it does not seem to lean out at all I can maintain 10.3 afr's if commanded right up t 6200 rpm ,it doesn't feel like a brick wall just not as strong as it should.Has anybody had a look at the dyno data in my first post to see how it drops off ?
11-27-2007, 11:49 PM
#10
TECH Junkie
valve springs?