Recently did an ls swap in my 71 GMC 4x4 with a crate GM 6.2 Aside from an annoying radiator issue the mill has been breaking in great.

My issue, I recently popped a code p0507: idle air control system revolutions per minute higher than expected

My idle is great, actually fairly low 600-700 when warm. No surges, runs beautiful. From searches on this forum as well as lstech it seems as though most common culprit for this code is vacuum leak. No other codes thrown just the P0507

Here is what I have done to attempt to fix:

Recent checked and tightened vacuum hose to break booster.

Capped the drivers side valve cover vent

Plumbed passenger side valve cover vent to intake

Capped EVAP

I cleared the code and it was fine for about three trips and then it triggered again.

I am using a GM wiring harness and computer.

I am attaching pictures to see if anything is obvious, thanks in advance.

 

I wouldn't cap the VC vents. Those vents are needed to replenish air pulled out by the PCV system. it's not clear what the blue cap is on in the first pic. The code is setting because your actual idle speed is higher than it is programmed in the calibration.

 

I had the same when I did my swap. At the time I had no vss hooked up to the pcm. That was the reason for my 507 code. Once i hooked vss no more problem. You could turn off the code in Hptuner's until you connect vss to pcm or just leave it off.

 

Thanks for your response. The blue cap is on the EVAP solenoid. Do you think I should run a line from the driver's side vent to the cold intake like the other side?

 

Great feedback, Sounds like I need to get a signal to the PCM, I believe that TCI has a pigtail that allows multiple pigtails. Right now I have my EZ TCU box plugged into the trans. Is this logic on the right path?

 

I piggy backed into my vss from my trans and connected to the pcm