99 L29 454 build

[L31MaxExpress]

Reading back through your posts and looking closer at your screen shots. The MAF, MAF calibration and or VE tables are definitely out to lunch. Bad or wrong injector data programmed into the PCM could also be contributing to the fueling error. Those long term fuel trims are sky high and it is also showing up as an extremely rich WOT air/fuel. Your narrowbands are reading 950mv and 980mv at WOT from all the added fuel the long term fuel trims being nearly +20% are causing the PCM to add. Even at lighter throttle the long terms are correcting for an extremely lean condition in the base fueling. My buddies truck with the extremely rich 11.8:1 commanded power enrichment air/fuel ratio and zero'd fuel trims from me correcting the injector data on his otherwise stock truck with LS1 injectors is running around 900mv on the narrowbands, much leaner. If you get your fueling corrected, I bet that engine wakes up alot.

You must be registered for see images attach

You must be registered for see images attach

 

[L31MaxExpress]

This was a L31 with a Lunati 218/228 cam, 1.6 rockers, 80mm BBK throttle body, Volant air intake, hooker 1-5/8" long tubes, dual 2.5" pipes to the muffler, high flow cats, magnaflow dual in, single out muffler. Fairly hot little engine. Bank 2 02 is dead because the wideband was in its bung. I was tuning in open loop anyway. At 12.7:1, Bank 1 narrowband is reading 867mv and MAF is reading 11,090 hz which means the engine is moving a ton of airflow. This was while I was dialing in the fueling, still fairly low total advance.

You must be registered for see images attach

 

[L31MaxExpress]

One point I forgot to make, is at +19.5 fuel trim, your PCM is fueling Bank 1 at the equivalent of ~289 gms/sec worth of fuel, enough for 345 hp and that is if the injector data is correct.

 

[Scottm]

Ok thanks! The latest tune came back last week. They reduced wot timing to 22-24deg and kept the cruise part throttle timing up where it belongs. Fuel trims are down to 1-2 percent, so they figured out the injectors, finally after 6 adjustments. There are strange glitches all over the chart. AFR is stuck at 14.17 until wot, then it drops to 11.8, which is pretty rich. The map sensor doesn't register at all until after the wot run, then it goes all over the place. The ecm has to be seeing the map accurately or it wouldn't run at all. Then the O2's always glitch out after every wot run.

In the early tunes with 22 deg wot timing, there was not even a hint of knock or knock retard. This pic shows 3 deg of kr and only 22 deg of advance. At 11.8 afr there is not a lack of fuel, so what other reason could there be to explain the knock at 22 deg, when it never did before? Injectors hit 56%, but who knows if they actually flow 36 lb/hr. Here is the actual log. I changed the extension from .efi to .zip, so download and rename it .efi

 

[BeXtreme]

Ok thanks! The latest tune came back last week. They reduced wot timing to 22-24deg and kept the cruise part throttle timing up where it belongs. Fuel trims are down to 1-2 percent, so they figured out the injectors, finally after 6 adjustments. There are strange glitches all over the chart. AFR is stuck at 14.17 until wot, then it drops to 11.8, which is pretty rich. The map sensor doesn't register at all until after the wot run, then it goes all over the place. The ecm has to be seeing the map accurately or it wouldn't run at all. Then the O2's always glitch out after every wot run.

In the early tunes with 22 deg wot timing, there was not even a hint of knock or knock retard. This pic shows 3 deg of kr and only 22 deg of advance. At 11.8 afr there is not a lack of fuel, so what other reason could there be to explain the knock at 22 deg, when it never did before? Injectors hit 56%, but who knows if they actually flow 36 lb/hr. Here is the actual log. I changed the extension from .efi to .zip, so download and rename it .efi

If you are running regular gasoline with 10% ethanol content, then 14.17 is Lambda=1.00. 11.8 is a pretty standard conservative 1.20 PE fueling ratio. You could go leaner if you want, but you won't pick up much(if any) power from it.

The glitches are concerning... maybe check continuity on all the ground points while moving the harness around? It sounds like maybe a loose ground connection.

 

[L31MaxExpress]

As long as the engine is warmed up and power enrichment or catalyst overheat protection is not adding fuel, the commanded air/fuel will be at whatever the stoichiomatric value is set at. MAP looks to be reading in that screen shot. Generally at low rpm, WOT it will read near the key-on barometric pressure and drop off a bit as the engine revs out and the intake tract starts to become a restriction.

Commanded air/fuel of 11.8:1 is exactly what I run my buddies 454 at since he works it hard towing. I do have his set to enable PE sooner than factory. His is setup to go into PE around 50% throttle, which is where I set most stuff.

 

[Scottm]

What is PE? power enrichment? Open loop?

 

[L31MaxExpress]

What is PE? power enrichment? Open loop?

Power Enrichment, which is open loop with a richer commanded air/fuel ratio.

 

[Scottm]

So that screen shot shows the afr at 14.18 all the way across except at wot. That's not right is it?

 

[L31MaxExpress]

So that screen shot shows the afr at 14.18 all the way across except at wot. That's not right is it?

It is once the engine is warmed up.