6.0 stage 3 leans out and dies

[ChadJ]

i need a little help in the right direction. basically im rebuilding an auction car that had aswapped 5.3 in it. I rebuilt a gen iv 6.0 with basically a com cams stge 3 with a holley short efi intake, 102mm throttle body. this setup is only running a map sensor. I have installed an AEM widband. the issue im having is i can get the VE table to make it idle decent. When i start giving it accelerator it leans out and dies. It has Stock LS3 injectors.68gtowith408strokerinfoloaded1.hpt68gtoidleto2000leanout.hpl. Im sure i dont have my math right in the logging. Still working on that. I have the serial connector from the blue wire coming into the hpt.

[5FDP]

Failing the MAF on this OS reverts to the secondary VE table, so any change made to the primary VE tables does nothing, that is how the early computers operated.

If the MAF is gone forever and you installed a separate IAT sensor you will need to apply the speed density enhanced OS upgrade in the OS tab. This requires a write entire to make it work. It will remove the secondary VE table from this OS to make it only have 1 VE table.

Looking at the file more, the MAP sensor data doesn't make any sense to me. I've never seen linear and offset data like that for a GM map sensor.

Did you apply the correct injector data? To me it doesn't look like it. You'll need to track that information down to get the gen 4 data into the gen 3 computer.

The open loop EQ ratio must be set to 1.00 for all temps basically above 130 degrees, it can not command leaner or richer than stoich for tuning.

The idle timing seems a little high to me and those timing curves are pretty rough. I'd start over with a stock 6.0 timing curve and rework it from there.

[ChadJ]

thank you! the map sensor is a 2.5 bar from holley. This car was thrown together to get across the block and sold. it didnt even have a DLC when i got it. Do i need to install an IAT sensor?

[gtstorey]

thank you! the map sensor is a 2.5 bar from holley. This car was thrown together to get across the block and sold. it didnt even have a DLC when i got it. Do i need to install an IAT sensor?

From Holleys website (without knowing your Holley part number)
"This MAP sensor is a direct replacement for GM # 12592525 sensor"
https://www.holley.com/products/elec...s/parts/870021

[blindsquirrel]

From Holleys website (without knowing your Holley part number)
"This MAP sensor is a direct replacement for GM # 12592525 sensor"
https://www.holley.com/products/elec...s/parts/870021

And what they mean by that is, it's the same physical dimensions and pin orientation. It can't be both a 2.5-bar AND electrically the same as 12592525 which is a 3-bar.

Also, if you call or write to Holley, they cannot tell you what linear/offset to use with that sensor because they do not know. It's meant to be used only with a Holley ECU where you set up the MAP sensor by selecting it from a pre-set dropdown menu. Holley does not know anything about how to make their parts work with a GM ECM/PCM. see also: Holley injectors.

[ChadJ]

Thanks for the help! Yes i read all the info off of the Holley website and researched a linear and offset value. i plugged in several different ones and the car wouldnt even run. Finally a 200 linear and a 10.33 offset got the car running and somewhat reading right? I used the RTT and got the idle dialed in mostly however slowly accelerating it gets to about 2,000 RPM and still leans completley out. I can see on the scanner what its doing to cause it.

[ChadJ]

sorry i meant to say CAN'T see on the scanner whats causing it

[blindsquirrel]

You need a MAP sensor that has real, known values. Sometimes eliminating unknowns is a valid diagnostic step.

It's not impossible to take an unknown sensor, connect it to a gauge, and determine the mV per kPa and then calculate the theoretical kPa at 5.00V (linear) and theoretical kPa at 0.00V (offset). Problem is, a gauge accurate enough to do that costs many times more than just buying a sensor with known values.

Why not just use the real GM/Bosch LSA/LS9 sensor?

[ChadJ]

i will try that. I just got the map sensor with the intake all new from holley. Kinda dumb that they dont have the the data for their parts?

[blindsquirrel]

I sure hope those injectors aren't Holley too.

What are they and where'd that messed-up data come from?

[ChadJ]

The injectors are factory LS3 injectors from a corvette. The injector data i copied from a tune in the repository from a stock corvette tune. Ive looked to try and find data on them but all i can find is injector data from a specific injector company.

[blindsquirrel]

Well your file only has the Injector Flow Rate table changed from stock 2000 Camaro. Injector data is more than just that one table.

https://forum.hptuners.com/showthrea...t-doesn-t-work

[blindsquirrel]

What type fuel system - referenced return regulator, or returnless/non-referenced (no vacuum hose to the regulator)? What is the base pressure if referenced, or static pressure if non-referenced?

[ChadJ]

it has a holley 12-170 fuel pump with the corvette fuel filter/regulator built in at 58psi. The injectors that are in it are the BOSCH 0280-158-051. I thought i transfered the other tables over also from the camaro when i changed the flowrate but maybe i didnt?

[blindsquirrel]

You need to put a fuel pressure gauge on it. That Corvette filter probably isn't happy with that 100 GPH pump.

[ChadJ]

Yeah i was going to do that, im trying to figure out how i want to do that and it look ok. Ive used this combo on a previous stock LS3 Connect and Cruise setup and havnt had any issues. Do you think its not keeping up and thats why its leaning out at 2000? Thats what it acts like which is what prompted me to get the stuff for a gauge so i can see what the pressure is doing.

[blindsquirrel]

I think it's pretty well known that the Corvette filter/reg can't bypass enough volume to keep the pressure regulated when it's fed by a big-assed fuel pump. Pressure will be too high.

[blindsquirrel]

Wrong injector data plus suspect MAP data plus unknown fuel pressure plus this VE:

screenshot.23-09-2022 14.36.15.png

... and you say it doesn't run right? I am shocked.

[ChadJ]

its got a factory LSA/LS9 now and the linear info for the MAP. This VE was just after RTT. Im still looking for correct injector data. It will be Monday maybe Tuesday before i get my fittings for the fuel pressure gauge. i know its a trainwreck but i greatly greatly appreciate your time and help!!!!black68GTOSpeedDensityEnhanced2.1.hpt

[blindsquirrel]

Verifying fuel pressure and injector data is as fundamental to tune file setup as verifying cam to crank timing is to engine building. Don't waste any more time or brainpower trying to figure anything out until those issues are sorted.