Hi everyone,

I just installed my cold air intake, using the ebay Prelude piping. It runs great (not that I can tell a difference, it feels about the same but with an N/A every little bit counts, right?) except it appears to idle lower on an uphill slope. On a flat surface my idle is usually 1100 to 1000 (higher then before I installed the intake). But on an uphill slope my idle dips back to "normal" 850 to 900.

I suspect this is either:
A) A small vac leak
B) (Since I have an s4) a MAF-being-level issue

I have tightened everything I know to tighten. I am running open smog pump (which I need to fix with a filter from Rotary Performance.) - but I doubt that would cause this. EDIT: Also, I have checked and continue to check the MAF - it is level. Not perfect but close enough. The bubble is well within the two lines on every angle I check.

Overall, it isn't a large concern to me. It drives fine. I'm just curious what you think might be going on.

Cheers & Happy Holidays,
iSP33D-for-J3SUS

 

I am pretty sure it is the MAF. I highly doubt it is a vac leak as a leak would leak regardless. However the maf is supposed to be flat so on an uphill it would seem natural that it would be affected. I wouldn't worry about it if the car runs fine otherwise. If any other issues arise then it could be cause of concern.