Power dropoff at 5800 RPM's and MAF jumps around
04-07-2007, 11:27 PM
#1
Power dropoff at 5800 RPM's and MAF jumps around I just got tuned yesterday, so everything is fine in the tune. At 5800 the power takes a ~15hp nosedive, then continues to climb back up. Also at 5800 RPM's the MAF reading goes from a steady increase in airflow to jumping all over the place.
Here's the dyno graph.
http://i86.photobucket.com/albums/k1...24/LE2dyno.jpg
And here's a video of the pulls, it doesn't sound like the ignition is breaking up or anything.
http://s86.photobucket.com/albums/k1...rrent=dyno.flv
Does this look like vavle float? And what does the MAF reading jump around mean? I'm guessing that is a sign of valve float as well? Also, there is 0 knock retard too, so thats not it.
Here's the dyno graph.
http://i86.photobucket.com/albums/k1...24/LE2dyno.jpg
And here's a video of the pulls, it doesn't sound like the ignition is breaking up or anything.
http://s86.photobucket.com/albums/k1...rrent=dyno.flv
Does this look like vavle float? And what does the MAF reading jump around mean? I'm guessing that is a sign of valve float as well? Also, there is 0 knock retard too, so thats not it.
04-08-2007, 12:14 PM
#2
did you log dynamic airflow in addition to MAF? the two should agree, even when you're running in factory MAF/SD hybrid mode. normally at WOT, even though the PCM uses all MAF once it goes past 4000rpm, it still does 'sanity checking' of the two. thus, if you tweaked only MAF, but not VE table, it might go into panic mode.
do you have your MAF descreened? that usually introduces a lot of noise to the MAF signal.
or it could be just a mechanical issue
do you have your MAF descreened? that usually introduces a lot of noise to the MAF signal.
or it could be just a mechanical issue
