Issues with idle after lt4 supercharger install on 2017 silverado

[LT4pwrdTexed]

Hello everyone. I have a bit of an issue that's driving me crazy. I have been working with Ben Charles on tuning my 2017 silverado 5.3 with an lt4 supercharger. Ben is doing a great job on the tune, but i have an idle issue that i can't seem to find a solution for. The truck just wants to idle high, between 1,300rpm and 1,500rpm in park, 850rpm-900rpm in drive. When in park, i tap the gas pedal and it will drop the idle to about 1,100rpm. But then it will slowly climb back up. The truck has an LT4 throttle body. I have tried everything and it just keeps idling high and throwing a CEL. I have done the factory relearn procedure- didnt work- no change, i have tried the throttle body clean on VCM scanner- didnt work- no change, I have switched back to my L83 throttle body- didnt work- no change. I have used carb cleaner to test for vacuum leaks around the intake couplers, and around the intake manifold runners. I just want to make sure i havent missed something. Ben has tried multiple different tunes, with no change happening. Any help would be appreciated. The codes its throwing are as follows:

P0121- Throttle/Pedal position sensor A circuit range/performance
P0507- Idle air control system RPM higher than expected
P1101- Mass airflow sensor out of self test range

[smokeshow]

I saw you post about that on pt.net. Have him post the file. We've been discussing torque modeling a lot here recently...this would be a good guinea pig example for virtual torque calibration.

[LT4pwrdTexed]

I’m not sure what pt.net is. I haven’t posted anywhere but here.

[LT4pwrdTexed]

Performancetrucks.net?

[smokeshow]

I’m not sure what pt.net is. I haven’t posted anywhere but here.

Ah, well then someone else has the same exact build and a similar name. Disregard

[Jonblarc7]

Ah, well then someone else has the same exact build and a similar name. Disregard

I thought the same exact thing.

[LT4pwrdTexed]

Oh ok, haha! What are the odds

[Ben Charles]

Just seeing this! Sent ya an email! Idle set point is at 650 roughly warm idle and we are at roughly 850-900 rpms with map kpA about 10 kpA too high and ETC at 3.x percent with timing at a low 1-2 degrees (which the ECM is doing its best to pull out spark/tq to lower idle speed..

I believe we have a small vac leak that’s introduced in the system by the KPA/throttle/spark reading...

[smokeshow]

Just seeing this! Sent ya an email! Idle set point is at 650 roughly warm idle and we are at roughly 850-900 rpms with map kpA about 10 kpA too high and ETC at 3.x percent with timing at a low 1-2 degrees (which the ECM is doing its best to pull out spark/tq to lower idle speed..

I believe we have a small vac leak that’s introduced in the system by the KPA/throttle/spark reading...

Post it up here! And the data

[Ben Charles]

I do a lot of Programs using the LT4 on many transplant setups (3 this week) that individuals pay for.. not fair for anyone just to grab that work for free and use it!


You seem to be a seasoned calibrator not worries about you... but many would use that work and profit off it.

[smokeshow]

I do a lot of Programs using the LT4 on many transplant setups (3 this week) that individuals pay for.. not fair for anyone just to grab that work for free and use it!


You seem to be a seasoned calibrator not worries about you... but many would use that work and profit off it.

Yeah I get it. I'll have to go solicit someone's freshly modded vehicle to use as an example lol.

[LT4pwrdTexed]

Just seeing this! Sent ya an email! Idle set point is at 650 roughly warm idle and we are at roughly 850-900 rpms with map kpA about 10 kpA too high and ETC at 3.x percent with timing at a low 1-2 degrees (which the ECM is doing its best to pull out spark/tq to lower idle speed..

I believe we have a small vac leak that?s introduced in the system by the KPA/throttle/spark reading...

I got it!

[LT4pwrdTexed]

We got it! Turns out, im and idiot and ran the LT4 pcv port on the bottom of the blower back into the intake. Rookie mistake by me! Ben Charles was the one that figured it out. Thanks Ben.

[smokeshow]

Oh man, I thought he was joking about a vacuum leak. lol

[Ben Charles]

Glad to help... when people work with me they typically get much more then just a program, they get knowledge and information with it. So for reference now we are at 9 percent throttle, mid teens timing, map KPA around 37, commanded and desired AFR match, MAF G/sec follows what I speculated and fuel trims within few perfect at idle

[GMCfast]

We got it! Turns out, im and idiot and ran the LT4 pcv port on the bottom of the blower back into the intake. Rookie mistake by me! Ben Charles was the one that figured it out. Thanks Ben.

Me and Ben have been working on my lt4 setup and I had a vac leak as well that caused the same issue turned out i missed the little nipple below the actuator. I was going to use it for boost gauge but forgot to cap it since I haven't installed the gauge yet lol.

[LT4pwrdTexed]

Lol, the smallest things cause issues when modding. It’s nuts.