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Big surprise, you guys nailed it. 63 psi of fuel pressure at idle/cruise, dropping very linearly and smoothly to 38 psi at 6k rpm. The fuel pressure also drops rapidly with key off. Going to build a...

Just posting an update.

Cruising around under CL VE, the LTFT look pretty solid. +/-2% or so except for deceleration coast (DCFO is disabled) and at idle. I'll have to read up on getting the AFR...

I'm using a walbro 255 with hydromat through a wix corvette filter/regulator. I can throw a gauge on it and see what that looks like as well. The pump or the regulator was a little loud when I first...

I do my best to buy quality parts from reputable sellers. The NB sensors are new denso units if I remember correctly.

I need to brush up on filters. I'll try giving this method a shot and see...

Right. If my tune matches the WB (which it does for the most part), the ST and LT trims will show the wide band error.

If I redo the tune with ST and LT trims only, the wideband would show it's...

This is the first time this setup has ever thrown a misfire code. Doesn't seem like the fueling should have change enough to start triggering misfires. But the lean logic makes sense.

I know it's...

Got a quick log of some CL MAF only driving on my way to work. Both the wideband and the fuel trims are pointing toward lean now, not rich. I did get a p0300 for multiple random misfire. I did not...

Those logs may not have any high load, low rpm. It does have tr6 plugs in it and they're new.

The afterfiring is worse when the engine is cold as well. I can get a log tomorrow on the way home...

Got it. Thanks for clearing that up. I'm starting to get my lists of channels and graphs built up. Nice to know I can log cylinder air mass regardless.

After correcting the MAF Fail Hz issue, I...

blindsquirrel

I started out using the stock scanner charts that have spark vs RPM vs MAP. I've moved on to the GRG charts (and some of my own).

Is it true that if I collect cylinder air mass,...

SiriusC1024, sometimes you can't fix stupid...

I'll go take new MAF only logs with the fail frequency restored. Totally missed the setting because it was under Diagnostics, not Airflow.

1Hz...

Hey all.

I'm working on my lq4/4l80 swapped suburban. Truck norris cam, 862 heads, 50lb flex fuel injectors, TBSS intake, ls7 MAF in a 4" tube, running 93 octane.

I've got the VE tune pretty...

Got some time to work on the Suburban today. Mostly mechanical stuff and putting the interior back together.

I did more reading up on tuning with a wideband. I moved to doing OL VE tuning and took...

Alright, two more drives down but no tune changes. Looks like I can remove quite a bit of fuel at mid load and low-mid rpm.

Anyone have any ideas on why it's still targeting 14.68 after I lowered...

I drove the suburban to work (about 13 miles of mostly highway) on the new tune. It seemed to idle quieter and run better overall. I haven't had the chance to review the log yet.

At least for now,...

That's quite a few changes compared to my posted tune. I can make sense of some of it but I'll need to do some research on the rest of it to understand what's going on. Still learning what I don't...

Hey all. I finally got my 1990 suburban with a 6.0/4l80e swap started for the first time last night. Took it on it's first drive this afternoon. List of drivetrain mods are as follows:

Engine:
-...

Great info on ethanol content here. I'll throw in that some simple mixtures math tells you that even if you run the tank down to 15% capacity with E10, then fill up with 100% gasoline, you're still...

Looked up the part about stoich. I'll probably keep it at 14.68 so if I do happen to get a "pure" batch it will be a little rich instead of lean. This thing will never see anything higher than 87 for...

I hadn't considered that at all. There's been ethanol in gas since before I started driving. So that really might be the last piece of the puzzle I'm looking for.

I have another MAF on my suburban...

Hmm that's frustrating. I'll repost them tonight.

While I agree that the MAF was probably 90 percent of the issue, I'm still getting LTFTs over 10 percent in the limited rev range I was logging...

Alright guys.

I reviewed my tune and the ONLY difference compared to the stock 4.8 tunes I have was the VE table. No idea when or how it happened, but whatever. I copied the 4.8 VE table over and...

Shotgunning is probably the best word for it. Plus I only work on it in fits and starts so the info isn't fresh in my mind. I'll pull together a 4.8 tune (much closer to the 6.0 tune you posted than...

Blindsquirrel I checked the primary VE table and see all that extra fuel you're talking about. 124 percent at 4800rpm, 105kpa. That makes zero sense. Checking it against the tunes I pulled data from...

Fuel pressure is officially ruled out.

A vacuum leak should affect high vacuum, low flow situations more heavily, right?

I will fail the MAF tomorrow and see how it does. That's a step I...