Gen 4 e38 dfco tuning

[04silverado6.0]

What is the strategy for tuning dfco on gen 4 trucks? What tables need to be altered? How much to start off and how can i verify my changes? Specifically with a cam swap.

[07GTS]

camshaft prob just raises the airmass a little for decel so it may not be getting low enough now to trigger DFCO, just look at your logs and adjust the thresholds to suit

[Cringer]

What is the strategy for tuning dfco on gen 4 trucks? What tables need to be altered? How much to start off and how can i verify my changes? Specifically with a cam swap.

What exactly are you want to change with this? I feel like most people either enable or disable DFCO. Is the truck doing something strange with it enabled?

[04silverado6.0]

The dfco does not come on after the cam. I would like to get it working.

[GHuggins]

07gts hit the nail on the head. You can also play with crank ref to enter and exit along with timing for both once it's properly going in.

[Cringer]

The dfco does not come on after the cam. I would like to get it working.

How big is the cam and did you install a high stall converter too? On my setup, to prevent bucking and surging on decel, I had the unlock the converter at 0% throttle which causes the engine to idle down so fast that DFCO is pointless/rarely kicks in.

[Alvin]

There is no harm in turning it off I've found. Can clear up return to idle issues on some cammed or heavily modified vehicles.

[LS ROB]

There is no harm in turning it off I've found. Can clear up return to idle issues on some cammed or heavily modified vehicles.

I've been wondering about this. My car cuts fuel fairly quick and the WB goes full lean. Normally get concerned when exiting the interstate as I have quiet a decel stretch and was questioning the effects of this. I normally push the pedal enough so that the WB reads numbers again. When you say turn DFCO off, does that mean there is no fuel cut or there is fuel cut? Forgive my ignorance.

[Alvin]

I've been wondering about this. My car cuts fuel fairly quick and the WB goes full lean. Normally get concerned when exiting the interstate as I have quiet a decel stretch and was questioning the effects of this. I normally push the pedal enough so that the WB reads numbers again. When you say turn DFCO off, does that mean there is no fuel cut or there is fuel cut? Forgive my ignorance.

Are you also worried about how lean the engine goes when you key it off?

There is absolutely no way you can hurt the engine lean in decel.

[LS ROB]

Are you also worried about how lean the engine goes when you key it off?

There is absolutely no way you can hurt the engine lean in decel.

Thanks for simplifying that. Next time ill just key off while coasting so i can use the hydroboost to steer better.

[Cringer]

Thanks for simplifying that. Next time ill just key off while coasting so i can use the hydroboost to steer better.

This forum needs some type of react emojis or something! Good stuff man! LOL

[04silverado6.0]

It is a truck norris in a 13 5.3 silverado. Stock converter. I believe I can figure this out with the info provided so far. What would be a good ballpark number to add to the airflow tables to begin with?

[mememe123]

Measure you cylinder air on cast down, and steady state driving. Let's say on coast it goes below .08g, and steady state is .10g. So you would have it activate at .07, and shut off at. 09. Just an example, you will have to mess with numbers a bit, if it gets too "jumpy". Same with TPS %.

[GHuggins]

^^^^ what he said. Make sure to adjust re-entry the same amounts as your adjusting the exit table with. Keep them .02 grams away from one another roughly if you have to adjust them a little separately

[GHuggins]

I've been wondering about this. My car cuts fuel fairly quick and the WB goes full lean. Normally get concerned when exiting the interstate as I have quiet a decel stretch and was questioning the effects of this. I normally push the pedal enough so that the WB reads numbers again. When you say turn DFCO off, does that mean there is no fuel cut or there is fuel cut? Forgive my ignorance.

You can play with the entry and exit crank ref's if you don't necessarily want it kicking in quite as quick, but want it coming out quicker. This is sometimes necessary for track cars that still use dfco, but don't necessarily want it kicking in right away - such as when they're in and out of throttle rather quickly and then to the other side of the spectrum lower crank ref's to exit, so it comes back "alive" quicker... You would need to increase to delay entry to keep it from kicking in so quick and lower exit to get out quicker.

[04silverado6.0]

I appreciate the help.

[LS ROB]

You can play with the entry and exit crank ref's if you don't necessarily want it kicking in quite as quick, but want it coming out quicker. This is sometimes necessary for track cars that still use dfco, but don't necessarily want it kicking in right away - such as when they're in and out of throttle rather quickly and then to the other side of the spectrum lower crank ref's to exit, so it comes back "alive" quicker... You would need to increase to delay entry to keep it from kicking in so quick and lower exit to get out quicker.

Thanks Greg. I appreciate you explaining the effects of raising vs lowering these tables.

[morepowerjoe]

Sorry ahead of time for the newbie question but I have to ask. Are you guys saying that you can run with the dfco disabled all the time if you want to? Because I disable it every time I tune my maf with my wideband. But I think I noticed the other night when I was out scanning with it disabled I was hearing a lot of pops out of the exhaust when I let off of the gas at high speeds. Is this normal? Thanks guys.

[04silverado6.0]

I would say that is normal in a way to have pops while dfco is off. Especially in ol, assuming rich conditions. But if you are shooting 9 foot flame balls out the tailpipe something is way off.

[morepowerjoe]

I would say that is normal in a way to have pops while dfco is off. Especially in ol, assuming rich conditions. But if you are shooting 9 foot flame balls out the tailpipe something is way off.

Yeah I was in open loop for maf tuning so I can see that now. But do you need dfco or can you disable it for good? The reason I ask is because I have an issue with my current tune when returning to idle when coming to a stop. My cam is a GPI SS3 vvt 228/246 646/638.