First Time Tuning

[lnash92]

Needing some help first time tuning on a cammed 5.3.

This is the run down on what I know about the car. It came to me as a fresh rebuilt 5.3 with a Howard's cam. I do not know the specs on the cam. It has a Velocity intake manifold with 92MM cable throttle body on it. The car is a 69 Chevelle with a 3.08 rear gear and 4l60 trans.
The car runs ok at startup and at temp. But stumbles sometimes at stop signs and red lights.

I changed and remapped the MAF to a 5 wire with the internal IAT sensor,after adding a different intake tube and filter.
Changed MAP sensor to a Bosch style to fit the Velocity intake.
Verified the lbs/hour on the injectors.
Used wide band O2 to map the VE tables.
I added timing but seems like it does not like it.

any thoughts on what i could do to help it perform better

Here is the log and tune

Thanks for any help.

[blindsquirrel]

Which MAF, is it still a 100K thermistor or a newer one that uses 50K? IAT scale is unchanged from a stock '99 LM7, is why I ask.

Changed MAP sensor to what? What part number? Does it have the same linear/offset as the one you replaced? MAP linear/offset is unchanged from a stock '99 LM7, is why I ask.

"Verified the lbs/hour on the injectors" how exactly? What injectors are they? And left the rest of the injector tables (Min Injector Pulse, Default Injector Pulse, Offset vs Volts vs VAC, Short Pulse Limit, & Short Pulse Adder) with the stock '99 LM7 data in them, I see. The flow rate is least important of all those. If flow rate is off you'll just have higher or lower numbers in the MAF/VE than reality and everything pretty much carries on without a hitch. But when it comes time for the PCM to calculate an injector pulsewidth that's very small, the numbers from those other untouched tables make up a much larger percentage of the final number. And one of your complaints is that it stumbles sometimes. I bet.

Used WB to map VE, yet the ST trims are showing that it's mostly around 10-20% too rich. Think that WB is to be trusted more than the stock NBs? You have two sensors from a factory system that both agree with each other, and disagree with the aftermarket DIY-installed sensor. Which one should you trust in that situation?

[blindsquirrel]

Is a 'Velocity intake manifold' one of those commodity Chinesium sheetmetal things?

[lnash92]

The MAF is a newer style card type.. I cannot find if it is a 100K or 50K thermister with the IAT built into it.

MAP sensor is a Bosch PN 0261230289 1 bar.

The injectors are PN 12580681.

I see your point on the ST trims. I was more worried about it running lean and burning a piston. I will slowly start pulling fuel out of it.

[IamKuahn]

I barely have an idea of what im doing with my tune as im still SUPER green to all this but my truck had idle issues at first and i messed with the idle settings and it got it to stop stalling at stop signs and red lights and decel. ill post my tune and see if you can use it as a reference. but again im going to say im still super new so take everything ive done on my car with a grain of salt and use caution....

edit- which honestly the idle settings i messed with couldve just been a bandaid for a really bad ve not 100 percent sure, but ever since changing em i havent had stalling issues.
edit 2 - you also have a p01 ecu mine is p59... there are alot of differences between our ecus so my file may not be of any help to you so sorry in advance if thats the case

[lnash92]

Where can I find all of this info at? I have looked for specs on the MAP sensor and injectors with no luck.

[blindsquirrel]

Find GM part numbers. Reverse search for which applications used those numbers. Go find stock file from something that used those parts.

[Alvin]

This needs lots of tuning.

The fuel trims are all over the place. I don't see a wideband on the log.

You'll need to pay attention to STIT and LTIT to know how far the base running airflow is off.

The throttle body might be a good part of the issue. There are a lot of really junky throttle bodies sold even by big companies right now.

As it sits your IAC at temp is over limits. Your TPS is occasionally sticking at 0.4% at zero throttle. See this link for info on how to setup a throttle body.

https://www.pcmofnc.com/2021/03/05/i...throttle-body/