Car: 2003 SL55 with 89K miles. Me: Above average wrenching skills.
: P0505 Idle Air Control keeps popping up. Rough idle when warm, but not all the time, only when it idles for about 2 minutes, and occurs infrequently.
What I've done: replaced rocker cover vent hoses; replaced throttle body (used) and TB gasket (new) and reset TB; replaced throttle pedal (used); shot some brake cleaner to find vacuum leaks around the intake and got nothing. Is this a vacuum leak possibly in the manifold somewhere? Could it be related to issue #2
: P0455 Evap System Large Leak - intermittent fault shows up maybe 1/3 of the time I've driven - may be related to Issue #1
What I've done: replaced gas cap, purge valve, charcoal canister, and even the fuel tank level sensor and gasket with used parts...all without luck. Checked evap lines for visual issues and added new clamps where removed. Nothing found. Do I need to get a smoke test to find this leak? Any DIY I have not done so far? The used parts may still be the issue, but I'm betting they are not the problem.
Solution: I knew these issues had to be related. And they were.
I found there was no vacuum being applied to the purge valve which meant there had to be a vacuum leak to the supercharger. I chased the line and found where it goes into the supercharger, and sure enough the little pipe was loose.
I had to remove the intake on the left-hand side to plug it back in. It is impossible to see and fix without doing this.
Hope this helps anybody else who has this issue.