Performing Idle Tuning - Motion 102tb and LSXrt onto 5.3L

[BROWNSTONE]

Just Upgraded from the LM7 truck intake. I made a carbon fiber CAI with an LS7 MAF (4") using stock air box, as well as the FAST intake and Motion 102 TB.

Looking for some basic pointers on getting the truck ('00 Silverado RCSB) to idle and behave enough to start scanning. Not sure if I can scan dynamic AF and compare to IAC counts as I have not completely thought through the effect of going from the 3" LM7 MAF to the card style. maybe fine? IAT will need to be scaled, but not certain on AF.

Was running very well prior to the intake and TB swap yesterday. It's 12:1 static CR and 231 degrees intake duration.

I had VE and MAF calibrations dialed in exceptionally well prior to this.

Won't idle for more than 5 - 10 sec... tried several combos on IAC vs Effective area , and BRAF but by no means have I covered all options.

Just trying to spend 2 - 4 hours instead of 2-- 4 days! LOL :-)

thanks!!

[Alvin]

A log would be helpful.

IAC vs effective area is just how the throttle body flows at different IAC positions.

If anything at all changed how that MAF was mounted it likely needs to be retuned.

[kevin87turbot]

Just Upgraded from the LM7 truck intake. I made a carbon fiber CAI with an LS7 MAF (4") using stock air box, as well as the FAST intake and Motion 102 TB.

Looking for some basic pointers on getting the truck ('00 Silverado RCSB) to idle and behave enough to start scanning. Not sure if I can scan dynamic AF and compare to IAC counts as I have not completely thought through the effect of going from the 3" LM7 MAF to the card style. maybe fine? IAT will need to be scaled, but not certain on AF.

Was running very well prior to the intake and TB swap yesterday. It's 12:1 static CR and 231 degrees intake duration.

I had VE and MAF calibrations dialed in exceptionally well prior to this.

Won't idle for more than 5 - 10 sec... tried several combos on IAC vs Effective area , and BRAF but by no means have I covered all options.

Just trying to spend 2 - 4 hours instead of 2-- 4 days! LOL :-)

thanks!!

That's likely the most difficult combo to get to idle properly that you'll ever tackle. I've tuned a lot of the LSXRT intakes, and they are absolutely terrible.

If you watch the intake manifold as you rev the engine, the entire intake manifold swells and contracts as you blip the throttle. The throttle body flange itself can deflect up to 1/8".

That being said, here are a couple tips that I'll give you if you decide to do it.

Add another 100-150 rpm idle speed over what you think the combo will need. That combo would normally idle fine around 750 rpm. I'd recommend 900 rpm to start with on this combo.

Keep the idle timing conservative and let over/under speed tables help you.

Keeping the MAF functional seems to help idle stability over a regular SD tune.

Run your IAC at a lower number than normal. You'd typically want it to be 50-70 on the IAC count. In your case, I'd start around 10-20.

Best of luck to you!

[edcmat-l1]

Couple things. First, going from a GEN3 MAF to a card style, it'll never run on the same MAF table. The table will be drastically different. Most of your "won't run" problem is going to be the MAF table is so far off.

Best thing to do is have your scanner running, fire up the engine and immediately turn on closed loop with your scanner controls. Let it start adding fuel. You'll see quickly how far off the table is. You could also start by just adding 30% to the table to get it closer.

Second thing is, the intake and throttle body are overkill for a 5.3.

[gametech]

I would go the easy route and tune out the MAF until I got it running good in SD. Then log dynamic airflow vs MAF hz and plug the resulting numbers into a new MAF table. This gets you a very close starting point for a MAF table that can then be fine tuned. Seems easier than guessing at new numbers for the completely different style MAF.

[BROWNSTONE]

Thank you! I have all MAF funct locked off for now. Temp iat is.close... I currently have a Math issue preventing AFR error logging. Does anyone have insight to this mat equation? Attempting to use AFR voltage transformed and "commanded AFR [sensor]"

..not sure why the sensor descriptor is on the commanded variable....

[BROWNSTONE]

Thank you! I have all MAF funct locked off for now. Temp iat is.close... I currently have a Math issue preventing AFR error logging. Does anyone have insight to this mat equation? Attempting to use AFR voltage transformed and "commanded AFR [sensor]"

..not sure why the sensor descriptor is on the commanded variable....

--


Now experiencing a hanging idle at about 1800.....

[Alvin]

Is TPS % returning to zero when this happens?