01 4.8 swap stumble on accel

[nobox351y]

01 4.8 in an 87 suburban w t400

Stock 01 fuel pump in 87 tank
pcm and harness are original to the engine
Shorty headers and a 1500 stalled converter are the only mods.

Swap has been up and running about year but never right. It has stumbled on acceleration consistently, especially after coming to a stop. I looked at a tune in a the repository and it has made it much better. Added some timing and took some fuel away.

Not expecting the truck to scream around town, just drive good w/ a little better fuel mileage than the old tbi 454.

The bank 1 Ltfts seem to be off the charts but this is the only thing I have looked at.

Would appreciate you guys taking a look at the tune to help me figure it out. I expected the stock tune to run fine. Not sure what the issue is.

Thanks,
Chrisburbnew1.hpt7 20 17 1.hpl

[5FDP]

Well, you have some problems going on for sure.

For one you either have a massive vacuum leak or it's starving for fuel, those fuel trims are horrible. Maybe even a leak in the exhaust before the sensors.

Bank 1 o2 sensor should not just drop out to under 50mv once you get into the throttle.

What is your fuel pressure like, it needs to be 58 psi.

Please put the stock timing map back in this, you can not run 30+ degrees of timing in this thing at 70-80%+ throttle, you are just asking for knock. Which you also aren't logging, add knock retard, injector pulse width, commanded AFR to your logs.

Remove the 5,500rpm delay for PE.

[nobox351y]

Put the stock timing map back into the tune. Will write the tune in the morning.

The 5500 delay for pe should be set to what?

Ill verify the the fuel pressure again in the morning. Checked it a few times and it was good. I am using the stock burb lines. 3/8ths feed and 5/16 return I believe.

Should knock through a code?

Im what you would call ignorant. No idea what things are supposed to look like.

Thank you. When I get this thing figured out ill be sending a case of whatever you like your direction.

[5FDP]

You can set the RPM delay to 0 rpm. Use the map kpa and your pedal % as the trigger for PE. Normally the 55-75 kpa and 50-70% throttle is always a good spot for PE.

Knock won't throw a code, only if one of the two sensor's or harness had problems would that happen. Spark knock will show in the logs if you have any. Most of fueling and timing related for why you see knock. Regular 87 octane is going to show knock, it always does. Too much timing or too little timing could cause knock as well, it's a game you play to find the right balance. For your sake I would run at least 89 octane in the truck prevent some knock and keep the power the motor could make.

I'd first try and figure out why your o2 sensors do what they do. Make sure the wiring is not mixed up side to side.

[nobox351y]

02 Sensors are not mixed side to side. I swapped the wiring and it would barely run. Bank 1 went extremely rich, and bank 2 went extremely lean. Swapped them back.

Does the bank 2 fuel trims look okay? If so, is there a chance the 02 sensor on bank 1 is bad? The wiring for bank 1 was not touched when working on the harness.

I reset the timing back to stock and have been running 91 octane fuel. During the last drive there was no knock.