DIY: Rough idle in cold start/cold temps LGT 07-09

They only sell the updated part. I didn't have to ask at all about any updates, just ordered new gaskets and for sure they were way different from the origionals.

Would this be the cause to my AFR ranging from high 14s to low 16s and then as i drive and cruise it pulses and runs lean and get some 17s in the mix as it pulses?

So I pulled everything apart today, can't get the old gaskets out of the manifold, any suggestions other than dental pick?

 

Thanks

Dental pick is the way to go. Just a couple bucks from harbor freight or local parts store

 

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I used this:

[ame=http://www.amazon.com/Sheffield-Tools-58780-Hook-Piece/dp/B002KHNCSS/ref=pd_sim_sbs_hi_4]Sheffield Tools 58780 Hook And Pick Set, 4 Piece - Amazon.com[/ame]

 

on passanger side. No way to get even 1/2 clearance on driver's side

You were most of the way there. Should have just pulled the manifold off.

I used a pick tool as well. The 2 on the driver side were a pita. I'm curious to know how folks pulled the entire manifold without disconnecting the fuel line. I could only lift the driver side up about an inch. I guess I could have been missing something but with some patience and careful maneuvering I got the gaskets to line up with the manifold and pushed down on it so they would seat.

First day of below 20 degrees since I replaced the gaskets and she runs smooth!

Cooking with Gas now. Nice!

Had the CEL P0304 for a while and have been dealing with it. Finally decided to deal with it. I just had new plugs put in, but this didn't resolve it, so I brought it back and said, "lets fix this btch!" They couldn't find the problem, but did a compression test and Cyl 4 was showing a little low (~110psi). Now they want to pull the motor and do a bunch of shvt; all of which would cost me a couple grand. No bueno.

 

Decided to do some research to try some inexpensive fixes first. This thread could be my golden ticket. I have all the same symptoms and it makes sense a little vaccum leak would cause a bit lower compression. Will try this out this weekend!!! WHOOOOT!!!

Ok...reading more and I'm back to being depressed.

 

Just replaced my clutch/fw and got 110k service done. I have zero more money to spend on this....

Ther eis light at the end of the tunnel... Keep moving forward youll make it to the end.

It was 10 deg F during my morning commute today, and I'm reporting back that replacing these gaskets totally fixed my cold engine rough idle problem. Warm engine idle is also smoother, and there is much less stutter during 1st and 2nd gear decel / coasting. After seeing the condition of the original gaskets and the oil and dirt buildup around them, I believe they were leaking badly when cold and possibly leaking slightly all the time. So yea, very happy with the results.

 

It's been mentioned by others earlier in this thread, but I would like to reiterate a few things:

1) plan for this to take 3 or 4 hours due to the extremely tight spaces

2) you NEED dental picks and a small mirror

3) removing the air pump and throttle body hose greatly increases access on the driver's side

4) IMO, the easy way to seat the gasket is to place it on the TGV surface, line up the tab, and push the manifold down (instead of working it around into the groove)

Edited February 10, 2014 by cww
spelling

Doing this on Friday

 

 

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Going to be doing this soon as well.

 

Been noticing the rough idle since it's gotten really cold, car acted up today right after the blue light went off and threw a CEL. Scanned it and I got misfire on all 4 cylinders.

I did this change on my 08 wrx with 120k miles on the clock. Same gasket issue as you LGT guys...

 

I didn't use a dental pick - and I was lucky enough that a 2.5mm allen wrench was able to fish the old gasksets out.

 

The old gaskets were much thinner, and rock hard compared to the new OEM ones. Also it is worth taking a look inside your throttle body and cleaning it out with carb cleaner. That caked up black ring might be affecting idle as well.

 

Took 4 hours total. 3 of the gasksets I was able to get out in the first hour. The last one - man... the driver side near the TB is a royal PIA.

Glad you got them replaced, when I did mine I did that hard one first along with the one next to it. I really didn't find it that hard.

Just did this job this weekend. 07 LGT

 

To gain more access to the driver side with the fuel lines, I pulled off the bracked of death covering the fuel lines, then pulled the 2 bolts holding down the fuel rail allowing the manifold to be pulled up a bit more maybe 2-3 inches. Made a lot easier. Also used a ratchet strap attached to the manifold and my rafters to hold it up making a very easy 1 person job

Edited April 1, 2014 by KSAL

KSAL, Any further insight on how you removed that bracket of death?

 

I attempted to replace these gaskets once and couldn't clear enough space to even attempt to take the drivers side out and replace. Had the car at subaru this morning and they want $675 bucks to replace the gaskets. I just can't imagine paying that much so i may be attempting this yet again.

 

Also since you so recently just did this... what did you do with the coolant resevoir on the passenger side of the intake manifold? did you just disconnect everything and remove it or did you figure out any tricks for that?

 

thanks for any help you can provide.

Intake can be taken off. Look at the fuel lines again. Clamps at the fire wall side can be removed in addition to the one clamp at the bracket of death. They are just hose clamps. Be ready for some fuel to come out (rag).

 

Of course thered are other items to disconnect. Intake tube support, Intercooler, wire harness support and throttle body connector... I'm probably missing a couple.

 

Don't fight it trying to keep it all connected. It should not take that long.

 

While your in there replace the fuel line clamps with somthing better than these poor hose clamps used. The ones facing the case on top of the motor. Max had also suggested earlier to wire wrap them. Your choice. It will help later if you have not had fuel vapor it may happen in the future.

BLKGT07

 

The best way to go about that sucker is to pull off the air mattress inflater thing. That will allow you access to the bolt that faces the front bumper. behind this

http://i236.photobucket.com/albums/ff290/KSAL02/image_zpsca9ace2c.jpg

 

the second bolt is located behind the air lines at on the top of the valve cover under the fuel lines, easiest to access with the battery out obviously, then with a shallow 12mm 1/4 with an extension.....OR if you have fancy tools like im so lucky to have swivel head extensions make it accessible with a 3/8 extensions and a shallow 12mm

http://i236.photobucket.com/albums/ff290/KSAL02/image_zps3ff5c4e2.jpg

 

lastly the back to bolts face the firewall, the top and easy one to get at doesn't really require anything special should be able to see that and get it with an extension. the bottom one.....is the killer. i tired to take as best a pic i could using a mirror to show where it is. it is WAYYY easier to get at if you pull the TGV off. ONLY PULL THIS OFF IF YOU HAVE 2007 and newer as those TGV's do not need to be rest and are not spring loaded. the pic shows UNDER the TGV and that open hole (i didn't put the bolt back ) is where the bolt is. the bolt that is in the pic is the bottom 10mm that holds the TGV in place.

http://i236.photobucket.com/albums/ff290/KSAL02/image_zpsba1cfdf3.jpg

 

As for the passenger side collant res. there is 1 12mm bolt holding it in place. I just took the whole thing off. I didn't worry about the lost coolant if i notice something i will top off another day. I DID NOT remove the manifold completely. I just took off enough to get 2-3 inches of space which is plenty and below is my redneck engineering on how to hold up that manifold so you have enough room to do this job solo (yes that is a rachet strap attached to my rafters in my garage). DO NOT crank the hell out of the strap just enough to get it up and out of the way. HOPE THIS HELPS SOMEONE!!

http://i236.photobucket.com/albums/ff290/KSAL02/image_zpsc68c154b.jpg

Edited April 10, 2014 by KSAL

^that's a quality 2nd post right there. good idea to use the strap to hold the manifold

thanks so much for the explanation and the great pics! I think this will help alot, will probably be attempting this weekend.

 

thanks again

I own 2008 Legacy GT and had the same issue (rough idle and flashing warning lights in cold temperatures) discussed in this thread for three consecutive winters. Visited Subaru dealer at least 10 times for diagnoses/repairs but the issue kept coming back.

 

Finally, last December (2013), I printed parts of this thread, brought it to the dealer and asked them to read it while I was waiting, which they did, and after my "gentle push" they agreed to change the gaskets between the plastic intake manifold and the tumbler valves.

 

It appears that this fixed the problem, as the issue has not reoccured at all, despite it being an extremely cold winter.

 

Thank you everyone for contributing to this thread, and especially to @bmx045, who correctly diagnosed the problem.

Edited April 21, 2014 by vkrupinski

Just wanted to post a little update for anyone interested. I completed this process a few weeks ago (Quite the extensive and frustrating task haha). I ended up getting the CEL again a few days later and finally gave up and brought it to subaru.

 

Either my intake manifold gaskets were ok or I had multiple leaks because when they did a smoke test on my car the leak is coming from below the TGV gaskets. In order to replace these they need to take apart everything I already did and more and they estimate its a 7+ hr job.

 

Bottomline, estimated cost of $900+

 

so heads up to anyone who can get a smoke test done first.. might be worth it to make sure which gaskets are leaking before tearing your car apart and finding out you had an additional leak.