High Idle, valve cover gasket just changed
Thread Starter
Junior Member
Joined: Mar 2008
Posts: 43
Likes: 0
From: San Diego, CA
2013 C63 Coupe, 2006 Evo 9 MR
High Idle, valve cover gasket just changed
Hi guys, looking for some advice. I just changed the drivers side valve cover gasket. Once I changed it out, I drove it around the block, everything seemed fine. I drove it today for 15 miles and I got error codes:
P0507
P0455
P0505
I checked around and noticed the fuel evap line(the rubber hose that connects to a metal line) was a bit loose, so I pushed it in a little more to tighten it up. I let the car cool down for a few hours. Then I drove it around the block again and got some error codes, but I didn't note which ones they were, I cleared them( should have noted them, but I was getting irritated at this point) I did some WOT's and some steady state cruising and I thought all was fine. I put it into the garage. Then I had a thought to see if it would come back again. I fired her up and while in park, it's idling a little high, 1.2k rpm. While in neutral, the idle is at 2k rpm! I put her in reverse, put it back to neutral and the idle seems to drop. I shut her down, then started her back up again and the same thing.
Any idea or thoughts? I thought the next thing to check would be the tightness of the Y-pipe to the throttle body, but that only has 2 clips that secure it right? top and bottom?
P0507
P0455
P0505
I checked around and noticed the fuel evap line(the rubber hose that connects to a metal line) was a bit loose, so I pushed it in a little more to tighten it up. I let the car cool down for a few hours. Then I drove it around the block again and got some error codes, but I didn't note which ones they were, I cleared them( should have noted them, but I was getting irritated at this point) I did some WOT's and some steady state cruising and I thought all was fine. I put it into the garage. Then I had a thought to see if it would come back again. I fired her up and while in park, it's idling a little high, 1.2k rpm. While in neutral, the idle is at 2k rpm! I put her in reverse, put it back to neutral and the idle seems to drop. I shut her down, then started her back up again and the same thing.
Any idea or thoughts? I thought the next thing to check would be the tightness of the Y-pipe to the throttle body, but that only has 2 clips that secure it right? top and bottom?
Super Member
Joined: Apr 2010
Posts: 781
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From: Bay Area, CA
E55 AMG, 72' Toyota Carina, 63' Ford F100, 72' Mercedes 250c, 15' Harley Davidson Softail
it's a vacuum leak. 90% sure it's the hardline which goes into the engine on the driverside. Is the one which is bolted down by the last valve cover bolt. Follow that line underneath the tb and check to see if it came loose. I had to remove the surge tanks to get down there and put it back in,but if you have girly hands you can probably squeeze your fingers in there and re-insert it 
I had the same codes come up and this remedied the sittuation
I had the same codes come up and this remedied the sittuation
Thread Starter
Junior Member
Joined: Mar 2008
Posts: 43
Likes: 0
From: San Diego, CA
2013 C63 Coupe, 2006 Evo 9 MR
Thanks guys! It was that hardline that goes to the back of the engine, got disconnected. What a b*%ch of a job to get it back in, I didn't have to take the surge tanks off, just got on top of the engine and used a flathead to use leverage to push it back in.
Thanks for all the suggestions again all!
On a sour note, I broke the bottom plastic tab off the y-pipe. It doesn't seem to affect much though, I did some WOT's and let off the throttle real quick and it's still on fine.
Thanks for all the suggestions again all!
On a sour note, I broke the bottom plastic tab off the y-pipe. It doesn't seem to affect much though, I did some WOT's and let off the throttle real quick and it's still on fine.
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Super Member
Joined: Sep 2010
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From: Wherever isn't gonna get me hit
'05 SL65, '13 FX4 Eco
Bumping this. I leave the car with my dad for a month and a half and I get it back with the check engine light on. (3rd time this had happened he must drive the **** out of it) Its throwing the P0455 code. So is this that hose that goes into the back of the TB that is loose? Is that the one I follow down to the engine? I'm doing my header install and CF lip tonight so I might as well get this done at the same time.
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Super Member
Joined: Apr 2010
Posts: 781
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From: Bay Area, CA
E55 AMG, 72' Toyota Carina, 63' Ford F100, 72' Mercedes 250c, 15' Harley Davidson Softail
Super Member
Joined: Sep 2010
Posts: 529
Likes: 2
From: Wherever isn't gonna get me hit
'05 SL65, '13 FX4 Eco
I'll take a pic for u today but it is a relatively thick hose that connects to the back of your y pipe on the intake. At least that was the hose that was disconnected for me. Haven't thrown a code since.
Super Member
Joined: Mar 2009
Posts: 937
Likes: 15
From: Alpharetta Georgia
2006 E55, 2006 saab 93 aero, 2010 glk 4m
