2003 Chevy Avalanche Idle tune help

[woodywoods]

I have a 2003 Chevy Avalanche 1500 Z71 with 5.3 liter.
The mod list is as follows
TBSS intake manifold
90mm GTO throttle body
LS2 cam and valve springs
shorty headers

The truck runs good except at operating temp idle.
At idle the truck runs erratic, the LT fuel trims change, sometimes it stalls.
I looked at some other posts about this type problem and got a list of the parameters that would be needed for the scan to get help

Avalanche minor tune changes.hpt2003 Avalanche idle scan.cfgAvalanche Idle and short cruise.hplAvalanche Longer cruise with varying conditions.hpl

I hope I attached all that right. There is the tune file, the config file, and two scans.

Ok I did some additional research and found how to adjust running airflow. I adjusted it till it was nearly perfect at operating temp, shut the truck off, went back later to scan and adjust for the lower temperatures, ran it till it was done doing its adaptive thing, adjusted a little on the lower temp cells till it heated back up to operating temp. The fuel trims at operating temp were all messed up. They keep changing. The LTITs changed also. They were within a few 10ths. Now they changed to about positive 5. I can't figure out why stuff keeps changing. I can't get it right if stuff keeps changing.

[mowton]

Are you resetting the trims after you have made a tune file change just before the next logging session?

Ed M

[woodywoods]

I did not reset the trims after I made the tune file changes. Should I have? By reset, you mean just go into the scanner VCM controls, to the fuel spark tab, and click on reset fuel trims right. Please forgive the ignorance. I'm pretty new at this and never had to deal with something like a throttle body change that totally changes how the idle air is controlled. Thank you very much for replying.

[mowton]

I did not reset the trims after I made the tune file changes. Should I have? By reset, you mean just go into the scanner VCM controls, to the fuel spark tab, and click on reset fuel trims right. Please forgive the ignorance. I'm pretty new at this and never had to deal with something like a throttle body change that totally changes how the idle air is controlled. Thank you very much for replying.

Yes, use the VCM function.....i press it several times, like the elevator up/down button :-)

Ed M

[woodywoods]

Cool thanks. Tomorrow morning I am going to try it out. The truck will be cold and I can get more done with the different temp fields and I will definitely hit the trim reset several times. I'll post how it goes and an updated scan file.

[woodywoods]

It worked great. Once I got in there I saw exactly what you meant about pushing it several times. I got the whole P/N fields done. I still have to do the in gear fields. After I did the RAF, I found a couple minor adjustments that needed to be done in the VE table. The truck idles much better and doesn't stall now. Thanks so much for the tip.

[mowton]

It worked great. Once I got in there I saw exactly what you meant about pushing it several times. I got the whole P/N fields done. I still have to do the in gear fields. After I did the RAF, I found a couple minor adjustments that needed to be done in the VE table. The truck idles much better and doesn't stall now. Thanks so much for the tip.

my pleasure, glad it worked out good.

Ed M

[HPtunergirl]

Having kinda same problem 2003 chevy 4.8 just put new aftermarket cam in and did the idle tune and the truck wont stay running or idling. having hard time starting truck as well!! please help!

[woodywoods]

Do you have the instructions on how to do the idle tuning? I have that thread on my desk top at home. I could shoot you a link later. Another thing and the best advice I have ever received about tuning. "If you're having a hard time and it just won't work, throw it all down, go back to stock tune, and mess with as few tables as possible." If you can't get it and you find yourself tuning in circles you messed with something unnecessary. All of the pre adjustments that need to be done for a cam are explained in the idle tuning guide. That will guaranteed get it to at least idle. After that you can clean up the quality of the idle.

[woodywoods]

Do you have the instructions on how to do the idle tuning? I have that thread on my desk top at home. I could shoot you a link later. Another thing and the best advice I have ever received about tuning. "If you're having a hard time and it just won't work, throw it all down, go back to stock tune, and mess with as few tables as possible." If you can't get it and you find yourself tuning in circles you messed with something unnecessary. All of the pre adjustments that need to be done for a cam are explained in the idle tuning guide. That will guaranteed get it to at least idle. After that you can clean up the quality of the idle.

https://www.hptuners.com/forum/showt...de-(w-pictures)

Hit that up, check it out, see if you missed anything. The base for a good idle with cam is to get the pre adjustments done that they explain in here, then your base running airflow. While doing the base running airflow scan pull up your scanner controls for fuel and while it is scanning repeatedly hit reset fuel trims so your BRA is set for a perfect fuel trim. When that is done put the new BRA into your tune, then do a scan for your VE table, letting it sit at idle for a good while when the O2 sensors are in closed loop to get that area very well. you want to get your VE table as close to perfect at idle as possible since you set you BRA to a perfect fuel trim.

Every adjustment you make to BRA changes your VE table so after every adjustment you have to go back through and re scan and adjust the whole VE table up to 4000 RPM and 50% throttle. Since the VE table is what the computer uses to check the MAF sensor and readings you will have to go back in and scan the MAF table and adjust it up to 4000 RPM. After all this is done you should have a great idle. These three tables are the basis for a good idle.