Lean after startup at any temp

[kyotey1693]

I've mostly got the VE tables dialed in an starting to work on the MAF but the whole time I've struggled with lean conditions after startup at pretty much any temp. When the truck is warmed up it seems to last about 45 seconds but when it's cold it doesn't seem to clear up until the ECT gets over 150.

I've played with the OLFA tables in those ranges but it doesn't seem to help. I thought maybe it was the afterstart enrich tables but adding to them doesn't seem to help either. It's almost like they're pulling in fuel instead of adding it.

But looking at the log, it's commanding richer than stoich but the WB is super lean. It's an AEM 30-0300. I've used this same sensor (new sensor but same setup) in my car, so I trust it. The placement of the sensor isn't ideal. It's in the center of the crossover pipe between the longtubes. It's a speed engineering kit for an 01 RCSB chevy. So it's farther away and possibly not getting the best airflow until I'm on the throttle. But the truck still runs rough when it's showing this lean so I think it's reading fairly accurately.

I thought about messing with the complex bias but this is the 12216125 OS so I think it should be ok.

My other big issue is transients when letting off the throttle, it goes super rich. I know some of that will change when I turn DFCO back on but I'm not used to seeing this much swing. Any suggestions on that or the lean condition?

Truck is an 01 Chevy, 5.7, Truck Norris cam, 4L80 swap, 80lb siemens, DW400 with external FPR set at 58 psi, long tubes and 3" exhaust.

Here's the latest log and tune.

Now MAF ONLY - Best so far Test 6 perfect shifts in test 5, raised shift RPM, played with TC loc.hpt
23-08-10 21-38-21.hpl

[blindsquirrel]

Misfires show up as lean O2 readings. If it's too rich, rich enough to 'run rough' as you said, of course the O2s (either NB or WB) will spike lean because of the extra oxygen that exits after a misfire. And would explain why adding fuel seems to make it even worse.

[kyotey1693]

Misfires show up as lean O2 readings. If it's too rich, rich enough to 'run rough' as you said, of course the O2s (either NB or WB) will spike lean because of the extra oxygen that exits after a misfire. And would explain why adding fuel seems to make it even worse.

Hmmm makes sense. I've never encountered a lean scenario quite like this but I guess it could be misfires. Would you suggest turning off the afterstart enrich as a test or just reducing the OLFA?

[blindsquirrel]

'external FPR', but not referenced to manifold?

[kyotey1693]

Correct. No manifold reference. It's just static

[kyotey1693]

Doesn't the evap purge run for about 30 seconds after startup? Since I'm tuning MAF only at the moment, does it make sense that the evap could be letting in unmetered air which is causing my lean condition right after a startup?

[blindsquirrel]

Are you logging evap purge status and fuel trim cell?

[kyotey1693]

Are you logging evap purge status and fuel trim cell?

I wasn't until just recently when that idea popped up. But just to be sure I plugged the evap port on the intake and it seems to have helped a little. It wasn't quite as lean on this past start up. I'm wanting it to cool down again to actually test it.

It really seems to stay lean until it reaches about 150 ECT, or if it's over 150 ECT it takes about 30 seconds to get back down to commanded EQ. I'm not sure if I should continue trying to remedy it with after start enrich or OLFA? Any suggestions?

[blindsquirrel]

Purge open will usually make it go rich, as the fuel vapors stored in the canister outweigh the lean caused by the vacuum.

[kyotey1693]

Well it's not the purge. It's showing closed and I still have that port capped on the intake. I have adjusted the OLFA to where it gets the numbers on the wideband to something acceptable but there is still a 30% discrepancy between actual and commanded EQ. It just doesn't make sense that it's pretty close everywhere else with the exception to transients.

I was thinking that it was possibly due the 80lb injectors. I know plenty of people run them with good results but maybe they're harder to manage at such low demand? But again it still seems like 150 ECT is trigger point for everything to start acting right. The only thing I haven't really played with at this point is the complex bias. I guess I'll try adjusting it next and see what happens.

[SiriusC1024]

Idk where you got that injector info. Short pulse adder is definitely wrong. I can tell that just by looking.

Here's the real deal.
https://www.aacorvette.com/injectordatahp.html

[kyotey1693]

Idk where you got that injector info. Short pulse adder is definitely wrong. I can tell that just by looking.

Here's the real deal.
https://www.aacorvette.com/injectordatahp.html

Thanks a lot man! That's definitely not where I got the data. Dumb question time... are the numbers already based on 58 psi? I see the multipliers in the Intro tab but I don't see where to select or input your fuel pressure to get right numbers back in the following tabs?

[SiriusC1024]

It's all for 58 psi. You can tell because almost all injectors are rated at 3 bar advertised. 80 lb/hr @ 3 bar > 92.38 lb/hr @ 4 bar.

unit conversion.png

3 bar with n-heptane is the typical standard for injector specs.

[kyotey1693]

Thanks man. I thought so but I figured I better make sure.