454 411 Swap

[Supercharged111]

I'm on 7.5.5 build 72. All I tune is my old garbage so no need for me to update. I was gonna ask how the hell to see what the idle wants but it looks like a peek at B4108 is going to tell me. If idle STFT is disabled, why does there appear to be LTFT active in that same RPM? Or does it just use the STFTs to influence LTFTs at idle when disabled without applying them? I'm used to a rich condition causing a fart smell to come out of the exhaust but judging by the O2s low voltage it seems a lean condition may do the same? I'm more familiar with what rich vs lean smells like on non-catted exhaust systems. A quick view of my most recent cruise logs are showing LTFTs in the 7-9 range so I'm thinking a quick easy 10% VE bump ought to help, no? I'm torn between making this run correctly on as stock of a tune as possible vs just hooking up the wideband and doing a calc.vet to cover something else up that I might be missing by using a small block PCM to run a big block. Like whatever is not allowing all my low load timing through, I think there are like 6 or 8 pids to log for that.

[Supercharged111]

So changing the O2 switchpoint to 450mV vs 480, adding 10% to VE, and enabling the idle STFT made a noticeable difference. Fuel trims are now in the -4-5 range which is a bigger swing than expected but the response is better and the TCC finally locks as I tuned it to. Seems it was misfiring a bit before. You know what I haven't done yet? A CASE relearn! Now that the laptop took a shit I think that ship just sailed. . .

[Supercharged111]

Well I'm at a complete and total fuckin loss with this thing. I used the bidirectional controls to play with adding and subtracting fuel and timing at an idle to no avail. It just sits there and lopes and misses at idle with good LTFTs. It never pulled this with the blackbox, I'm completely fed up and out of ideas. None of this makes sense. It has the proper proportion of air, fuel, and spark so how the hell does it idle like it has a donkey dick cam?

[Supercharged111]

And the case relearn won't work. All I get is no reply, try again or an instant OK and no stumble when I rev.

[joecar]

Bidir control might not be working on this PCM.

Is it running from the MAF or from VE...?

[Supercharged111]

Both. Fuel and spark bidirectional is working, but it didn't cure the lope. I bumped base airflow to the point that I believe it now trims air and LTFTs are now all negative. Timing is definitely good enough.

[joecar]

You don't have any air leaks at the intake manifold...?

[Supercharged111]

Not that I'm aware of. Only thing I changed was the PCM. Idled great before and now it sucks bigtime.

[statesman]

It has the proper proportion of air, fuel, and spark so how the hell does it idle like it has a donkey dick cam?

Post a log of your idle and your latest tune file. Include the following in your log...

IAC counts
Spark
MAF
MAP
RPM
TP
Front O2 sensors
Short and long fuel trims

[Supercharged111]

Here's some of that, we'll see how many reboots it takes to capture all of those pids.

Dually Log 10 Idle After Idle Airflow Bump.efi
Dually Log 8 quickie idle.efi

After log 10 I bumped VE at 400 and 800 RPMs up to 55 kpa as there was a weird dip there in the stock map. I did that because I saw 3.9% positive LTFTs at idle on occasion. Fuel trims ought to be all negative if I can capture a suitable log.

As far as I know, firing order is the same from the 5.7 to the 7.4 (cylinders are also numbered the same), so I really don't know what the asspain is here. I double checked pin colors and locations, the only CEL I'm getting is for EGR which is turned off anyway. Unless it's stuck open? Drivability is good, just seems to not be responding and giving me the power I was expecting. It's better than stock, but not dramatically so. Off idle stumble sometimes isn't that bad. That feels tunable, but this lope from a steady state idle just feels like something is broken.