kbob999

Car: 2003 SL55 with 89K miles.

Issue #1 : P0505 Idle Air Control keeps popping up. Rough idle occasionally 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? Any ideas where to look next?

Issue #2 : P0455 Evap System Large Leak - intermittent fault shows up maybe 1/2 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.

Any help would be appreciated. Will post results when they are found.
Thanks!

kbob999

Found it! There is a small pipe buried under the left intake that supplies vacuum to the purge valve, and created a vacuum leak into the supercharger. Plugged the pipe back in, after removing the left intake, and all is well. Cannot be seen without removing the intake.

cadbob

Nice find and lots of patience!

Afr00t

Can you please take a more detailed picture of the location and how to get access to it? I think i'm having the same issue i got p0455 and a loss of power

kbob999

The E55 has this vacuum line visible w/o taking off the intake manifold, but the SL55 does not. You have to remove the intake to see it. Not sure about the CL55. Here's a shot of the intake removed on the SL55...

Previous shot is a closeup of the left rear intake bank in this same picture.

Note that the issue can one of the following: purge valve; gas cap or gas cap seal; vacuum lines to the gas tank; vacuum sending unit sensor in the gas tank fuel level; seal to the gas tank fuel level; gas tank filler neck or vent hoses; charcoal canister and the valve on the canister; something else in the fuel system???

I have some of these used parts on the shelf in working order if you want to buy and test with them (purge valve, tank sending unit, gas cap seal). Send me a message and I'll send you part numbers of what I have.

Start by seeing if you have vacuum to the purge valve. To do this, remove the intake to the purge valve. Then start the engine and put your finger on the purge valve intake line. If you have vacuum, work your way downstream to the tank by testing the purge valve next.

The SDS is an excellent tool to walk you through the process. I used it to see that I had no vacuum at the purge valve, which told me it was upstream (toward the engine) of the purge valve. Most people start at the gas tank cap, which is cheap and easy to fix, but at the far end downstream. This is where I started, which was a mistake.

Good luck and post your results for others to see.

Afr00t

Did your cars performance hinder as a result of the line being out of place? Or did it drive fine? Can you explain the symptoms if possible? Thank you for the helpful replies and info

kbob999

There was a stumble just off idle due to a lean mixture. No affect on wide open. That was the only issue I felt during driving. Idle was a little higher, but the computer could not close the throttle any more, so it raised the idle. That was it.