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I've been fighting this issue for a while to no avail. Thought I would see if you guys have any opinions. Essentially, the engine goes lean briefly when I'm doing a pull in PE. It almost always happens, regardless of whether I am running SD or MAF only, the MAF trace is smooth, injector pulse width doesn't dip and the spike never seems to happen at the same MAP value or MAF frequency. I can't wrap my head around it. The only thing I keep coming back to is my fuel system. It is a LS3 C6 with a BAP and ID1000s.
I know the hobbs switch is supposed to activate at 4psi, so I would expect to see the spike occur around the same MAP value each time, but it doesn't. Thoughts?
Happens all of the time on E67s but not so much on E38s, and no it's nothing to do with the prediction coefficients. I'm assuming you turned this off??
I did not. This is the first GenIV or GM that I've tuned.
I'll give that a shot. Thanks NicD!
The more time that goes by with all this I'm really starting to think going with Holley would have been a good idea... So many nuances to these factory controllers.
The more time that goes by with all this I'm really starting to think going with Holley would have been a good idea... So many nuances to these factory controllers.
Well look at it this way, anybody can go fast on a standalone. Accomplishing it with a factory ECM is much more difficult. It's the same reason I'm not switching to a standalone in the C6 Z06 until it runs a 7 just because.
Good grief... 3.5PSI, 6* of timing, 11.4:1, what's going on there? Seems awful fat and no timing for such low boost.
I agree. I don't know why the knock sensors keep picking up so much activity. Once I get this dialed in I'm going to throw some E85 in the tank to see if it goes away. It's probably false knock but who knows.
I agree. I don't know why the knock sensors keep picking up so much activity. Once I get this dialed in I'm going to throw some E85 in the tank to see if it goes away. It's probably false knock but who knows.
What target AFR would you recommend? 0.8?
Granted I don't know what power adder you have. But with a turbo I'd generally still be .82-.85 or so at such low kpa, I don't drop down to .78 until its lit.
Hopefully, you should be able to run double that timing! Granted even 12* still isn't that much.
NicD, turning off Desoot was a game changer, your the man. Fuel traces are far better now.
Still seeing crazy amounts of knock retard with seemingly minimal timing advance. At one point I get up to 10.1 degrees of KR with 22deg commanded at 3500rpm and 109kpa. That doesn't seem like too much timing to me...
I'm running an Novi 1500 centrifugal at 7psi. I'll be going to the strip on Wednesday so hopefully I can get a few passes and play with things a bit more.
10-07-2019, 09:22 AM
Lean spike during PE 
It's the same reason I'm not switching to a standalone in the C6 Z06 until it runs a 7 just because. 
