2014 5.3 Silverado Turbo Idle.

[Badassbird]

OK to all those who are much more educated than I. I have a 5.3 Silverado with custom turbo and camshaft. The base tune has been written but I am trying to get the idle in the ball park before commensing any real tuning. With a commanded idle of 680ish it will pull timing badly negative and idle roughly 200 rpm lower than target. This also tries to spool the turbo at idle which is kinda funny. I have tried all the normal things I have done with cammed C7s and no matter what I change,both up or down, it does NOT make a difference at all. I have tried the torque reserves,driver demand in idle area,external limit and spark everywhere. I raised the spark and lowered the spark but it only increases or decreases the TM spark. I raised the minumum spark at one time but it makes the idle very eratic. The file and log are attached. Any insight would be appreciated.

[GHuggins]

Tried your airmass a,b,c,d and spark tables under the torque management engine section yet? Increase the a,b,c,d tables by torque percentage gain hypothesis and your spark airmass tables by 1.05 to 1.1ish at a time. Then the idle-torque limit-external load and limit offset are also some other good ones... External load, just increase the positive numbers although with your setup you might also want to increase the negatives or make them more negative for any possible throttle hanging open problems that might occur from the added boost and airflow. Just keep all of your mapped tables smooth with the changes being made to them... The limit offset you can just increase up to around 100ish and that should be good enough.

Haven't checked your tune out, but if all else has been set, this is where I would start.

[Badassbird]

Tried all of that but made zero difference at all. I will play with them again.

[GHuggins]

Well, the idle reserve is more or less your idle airflow equivalent table, then your airmass tables are your overall torque model... How much have you increased all of these by exactly? Have you tried raising ALL of the torque coefficient tables in unison? I typically like to raise the airmass a,b,c,d tables in all of the coefficient sections by torque expected gain from dyno results then raise the other tables by 40 to 50% of that, but sounds like you might need to do more? I haven't had any issues with this method yet, but who knows, I'm probably doing something wrong. You could also copy and paist over all of the Z06 vette tables and start off with them, but it is a different engine with the added drag of the supercharger...

Then there's the adaptive idle tables which more or less look just like the gen 4 proportional and integral tables, but I'm unsure how to adjust these just yet as I've not played with them any. Would imagine they would be the same though.

Jarrah does quite a few of these newer gens and understands them much better than I. Perhaps he will chime in...

Final thought. With the added ease of airflow due to the turbos, what happens if you cut the speed control reserve and positve sections of the external load in half? Only reason I ask is because I've also seen where timing will increase and the engine will idle better with the two tables lowered in some instances instead of raised... Again I've only tuned a few of the gen 5's so far and not as keen as others on what the tables do. Something possibly worth trying though...

[Badassbird]

I have raised and lowered the idle reserve by double and half. No difference. I have also raised and lowered the torque tables by 10 percent up and down to no avail. Just doesnt make any difference at all no matter what I do.

[Ben Charles]

Commanded Tq IS WAY TOO LOW at 236ft lbs, that's why the negative timing. Try increasing Peak tq at Idle ranges and hit the Tq coefficient tables with a decent change ( that's one way of increasing "Max Engine Tq")


IF you want a easy way to get timing back at idle, put the Minimum spark to something close to desirable this will keep the timing up. Not the right way to do it, but it does work at keeping timing back in, but may make things unstable due to "cheating"

For what its worth my stock C7 idle Max tq was around 345 ft lbs, after modding the Tq C tables around 385 (10 percent change) and timing increased about 5-8 degrees (less Tq managment spark)

I didn't look through the tune a ton, but unless this rig is making 1000rwhp the DD table needs some work.

[ayousef]

are you using the stock throttlebody? Im asking because I tried a 6.2 throttlebody on my 5.3 and it went absolutely nuts and wasnt worth the effort trying to hack the coefficient tables to make it work. However if you are seeing such low timing you need to REDUCE your airmass torque coefficient tables

[GHuggins]

are you using the stock throttlebody? Im asking because I tried a 6.2 throttlebody on my 5.3 and it went absolutely nuts and wasnt worth the effort trying to hack the coefficient tables to make it work. However if you are seeing such low timing you need to REDUCE your airmass torque coefficient tables

Don't know if you got your problem fixed yet or not, but ayousef is correct. Just ran across this myself on a stroked motor. Reduce your torque coefficient airmass a,b,c and d tables in the idle rpm areas. By the looks of it, you could probably start by multiplying them by .8 and be OK.

If you haven't already figured it out, hope this helps.

[Ben Charles]

When you change any rpm value in the tq coefficient table even if its just 1 cell it remaps the entire table. I was modding the table in the 2000rpm range and noticed idle and wot changes on the scanner

[GHuggins]

When you change any rpm value in the tq coefficient table even if its just 1 cell it remaps the entire table. I was modding the table in the 2000rpm range and noticed idle and wot changes on the scanner

Boy these things just get more and more confusing

What kind of changes were you seeing when you were messing with the 2000 rpm cells such as if you increased them, would they increase the other areas respectively? Or would it be the oposite?

Thanks Ben

[Ben Charles]

I was experiencing a Max Engine Tq dip from 1800-2600 rpms (like a 200 ft lb dip), couldn't feel It, but I was seeing it in the scanner. I played with the Tq coefficients only in that RPM range. What I noticed was a about a 30ft tq difference (increase at idle) and the part throttle areas still had the same "Curve" but the Max engine Tq values were much higher now like 125 ft lbs higher (I performed a 20% increase) and throttle felt terrible/laggy.

What actually fixed the Max Engine Tq curve was me dialing in the GMVE table. Figured out even if you disable the SD portion of the tune, the E92 still uses it to calculate data so its basically a requirement to tune now.

I think it all goes back to dialing in the GMVE/MAF tables, get spark where it needs to be, make sure nothing it limiting throttle, play with the Tq Coefficient tables to get the correct Tq curve for the engine, and play with the DD tables to get the correct feel. You can alter DD to some extent for "feel" but you still have to play nice here b/c if you go too much the throttle will be way laggy. Too low of a value and the car won't move (did that today haha)

[Badassbird]

It seems I was fighting a mechanical issue. Owner took it back to the shop that did the install ,brought it back and now it is good. Thanks for all the help guys.

[totalengine]

It seems I was fighting a mechanical issue. Owner took it back to the shop that did the install ,brought it back and now it is good. Thanks for all the help guys.

What did the problem end up being with this truck? What mechanical issue? I have a car that does the exact same thing.

[Badassbird]

Had a cracked plug and a burnt plug wire.