dc_justin

iTrader: (13)

Very nice. You can get away with a bit leaner I'd bet. Ben @ EFI101 (EFIGUY on the EFI Live forum) is running the semi-closed loop table at 16.5:1 in the lower ranges. Any leaner and he started to lose power, but at that point he did well on his milage.

kbracing96

iTrader: (26)

YA, I'm actually a little leaner and a little higher in the kPa at 2400 range, that's an older screen shot, but haven't gone leaner then 15.8, might have to try that

02sierraz71_5.3

iTrader: (2)

I wish HP tuners had a table like that

Yelo

They DO...you just have to purchase a 2-bar speed density OS (same thing for EFILive)

dc_justin

iTrader: (13)

With EFILive you don't have to be in speed density

I just purchased the upgrade from personal to commercial and will be flashing in a custom OS as soon as I get my smog check.

Yelo

Cool !!

I will say though that I'm not really sure I'd WANT to trust the MAF in a boosted or lean cruise situation....I think for making BIG power that SD is probably the safer (if harder) way to go

dc_justin

iTrader: (13)

I'm running over 8psi of boost through the MAF without problem.
And you would only want to run lean in low load situations, where the MAF would be registering low airflow numbers to begin with and should be more than capable of operating effectively in that area.

dewmanshu

iTrader: (4)

I believe (can't tell looking at his sig) but Blown 364 is still using the maf. That's just crazy to me. It's not so much the low laod area, but man where do they max out at? 59.xx something? He's in the 11.xx's, that MAF has got be saying to the pcm, "You are on your own from here!"

Yelo

8psi is OK throught the MAF...it's when you get to 11psi+ that I start to get worried about maxing out the MAF. Once you max out the MAF you're relying on the VE table for fueling but since the VE table max's at 105kpa all the PCM can do is carry the last VE value the rest of the way up through boost....and if you run lean up top because of this the engine will never even know. THAT is why I'd rather run with a custom 2-bar SD OS...the VE and PE tables are extended out much further so that you can actually tune all the way to 2bar (29psi) without having to rely on the MAF (or deal with the restriction it creates). I'm currently running in NA SD mode and I have to say the truck runs MUCH better because of it, when I finally go FI I'm not going to even try to tune it with the MAF

dc_justin

iTrader: (13)

Once the MAF is maxed you rely on PE to increase fueling, not VE (in a 1 bar environment). That is how you'll see guys running 700+hp motors through the MAF. They have to command insanely rich targets, such as one guy I read about commanging ~8.5:1 to achieve 11.7, but it works for them.

In a 2 bar OS, in order to default to the VE when you've reached that MAF Maxpoint, you'd have to lower the high frequency fail limit to the 12000hz level. Otherwise, once you hit the rpm threshold for airflow calculation (stock at 4000rpms), the PCM would default to using the MAF only for airflow measurement rather than calculating it based on MAF and MAP input. PCM would still assume that the MAF is measuring accurately and would assume 60#s of air is coming in when in fact it could be considerably higher.