Any suggestions are welcomed! I noticed while tuning and data logging my MAF voltage and load(VE) were low...MAF voltage max was just under 4volts, load would max about 70%. I cleaned my MAF and no help.

Swapped MAF for 90mm lightening and CAI (same price as stock MAF), and I have the same condition, MAF voltage max just under 4V, load 80% max.
any ideas?

This is on a 99 5.4l 2v Superduty, NPI block with PI cams.

Thanks,
NCON

 

You'll never see 100% load with a N/A Triton (if you're running a truck intake), and rarely will see that with most other 4.6L's. 80-85% or so is about the best it gets.
I've seen approx 98% load with spikes of just over 100% at certain RPMs with my Tbird in datalogs, but it's not a good comparison. That car has ported heads, cams, high compression, etc, etc, etc.
JL

 

Thanks Johnny, I thought I was leaving ponies on the table...but this makes sense with the torque focused truck intake. The MAF voltage seems ok also?

And what do you think about O2 sensors with 150Kmi? I hear they slow down, would this impact fuel economy? I am cautious to lean my afr without a wideband, but feel this is the next stage to higher fuel economy...do you think there is much room to play by leaning it out Johnny? 15mpg would be great, I have only seen 12, with a good HP gain.

Thanks again,
Neil

 

This post could get very,....very long, so I won't do that. O2 sensors, if they're over 100K miles, they probably are in need of replacement. They don't last forever,and over time, they shift their switching point and economy will suffer. As for leaning the fuel mixture, at low load cruising under closed loop (stoich), there's not much that can be done for economy-that's about as good as it gets. You can bias the O2 sensors a bit lean and that helps some,but we're talking about tiny amounts. The best thing is to use a good shift/lockup schedule if it's an automatic, keep it in closed loop as much as possible, and reduce parasitic drag. How are you tuning it?
One other thing...that 90mm Lightning MAF is WAAAYY overkill for a N/A 5.4L. I run an 80mm Lightning MAF on my Tbird simply becasue it was cheap,and had more range than the OE Tbird MAF. I'm still not able to use the entire range of the MAF-it's good for quite a bit more HP than what I currently have, and would be good to use even with a mild SC setup That 90mm MAF may be causing some fuel economy issues since it can't get as fine of a resolution with the airflow that your engine is consuming since it's got a wider airflow to voltage range than a MAF that's more suited for N/A applications.
JL

 

Good input JL! Yeah the new 90mm MAF (with 9in superstack filter w/ plate) was less than a stock replacement MAF at the local parts stores...and I needed to see for myself air was flowing enough! It makes sense the bigger MAF doesn't go full voltage as it clearly bound by the longer intake...but maybe I should skew it up a bit.

I do still have that "ramhead" early y-pipe in the exhaust, w/ gibson cat-back...and could be costing me some flow in exhaust restriction, understanding some restriction is needed [2 into 1 here] to keep peak torque in a lower RPM range.

Using the Sniper Special forces stuff, very easy and flexible w/ datalogging, and for the same price as a canned hand-held unit. Idling, the engine sounds completely different running a 93tune and global timing +2degrees, is that normal? Also I note my closed throttle TPS voltage is .96volts, and might be an issue...but I haven't found much info on tuning 5.4's except from the mustang folks.
NC

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1999 F250 SD/SB/SC Lariat 4X4 5.4 2V(NPI w/ PI cams) / 3.73

 

I read something about a tuning feature to cut fuel in a hard decel condition, has anyone tried this? JL?

 

Can't help you with that Sniper software....sorry.
JL

 

Thats cool JL, I like the sniper because I know computers and it opens options to us end users...

Do you think a new y pipe is worth the $200 it will cost me to swap it out?

NC

 

I noticed a difference when I swapped it out on our Excursion....but it has the more choked up later version.
JL