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

You don't need to take apart everything for the TGV's to head seals. See my click here link, you'll see I pulled the whole intake assembly off in one piece, just remove the 8 bolts that hold the TGV's to the heads. Granted I did this with the engine out of the car, but it can be done with it installed.

 

Sorry to say it's not 7 hours.

My leak was a crack in the manifold by the throttlebody couldn't see without removing it and smoke came from under so that was hard to tell till it was all apart

 

 

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Just did this while going stage 2... wow the oem gasket inside is about 1/2 as tall...

 

No more shuttering at stoplight and no shuttering at cold-start (today was cold in NYC).

 

Can't 100% say it was the gaskets, maybe the ots stage 2 map? but whatever it was, problem solved.

 

No greater joy than coming to a stop and not getting hiccups!

just did this over the weekend, couple things to note:

 

I have never ever taken the engine cover off. Prior to this I've only done oil changes and front end links on my car so I must have taken a bit more noob time. (I also took my fuel pump out but thats just unscrewing shit)

 

It took me all in all ~4 hours. If i had to do it again i think I'd be <3 hours.

 

Have some coolant on hand or make sure you catch all of it coming out of the turbo coolant resevoir.

 

MAKE SURE YOU GET A DENTAL PICK (I got an 'o ring pick' at canadian tire) i would NOT have been able to do it without that.

 

I did not have to move the fuel lines - I wedged an allen key in between the intake and TGV where the bolts screw in (dont do this on the gasket mating surface) and was able to lever up the manifold enough to get all the gaskets out. but i did have to take off that air mattress pump thing that KSAL posted a couple posts up. Made angling the pick to get the drivers side rear gasket out much easier.

 

I used the method of putting the gaskets on the TGV valve and carefully pushing the intake manifold down onto them to push them into place - worked perfect.

 

this thread really helped me thanks! seems like it solved my idle issues! Now if only I hadn't snapped off my stupid plastic nipple on my BPV (i jb welded it back into place - I think its fine)

Has anyone used gasket part number 14035AA492 on their 05-06 LGT? I'm experiencing a rough idle and RPM drops until my engine is warm, and was looking to replace these gaskets.

 

When I search this part number it looks like these fit on all 4th gen GT's, but several posts here tell me that they don't.

Not sure what the p/n is but they are orange and much larger.

 

I'm sure no dealer would sell you the old black ones.

 

tighten the gas lines clamps too.

I'm in the middle of this job on my 2007 LGT. Everything is almost apart, except for one bolt. I cannot find a good angle/space to get to the passenger side's back-most inner-most bolt.

 

There is the coolant hose in the way, but the real issue are two hoses that have a mesh cover over them. They are not moving and I'm reluctant to force anything.

 

UPDATE: Got it. Just needed to move around the hard lines. Lots of interconnected pieces back there.

 

UPDATE 2: Completed the passenger side. The original gaskets were tough to get out. My guess is that these get a bit more heat due to proximity to the turbo. The driver side was a no-go. The fuel line bracket simply didn't allow sufficient vertical movement to get more that a 1/4 inch or so. I did try to get the gaskets out and the section with the tab dropped much easier than the passenger side. I buttoned it back up. Hopefully the issues were all on the passenger side. Time will tell.

 

While this job can be done in the driveway/garage, it is not a job for a novice. For my '07, that fuel line makes it apparently more complex than others have experienced, though I know others have mentioned it as a problem. I'm just passing this along in case others want to dive in. I think the job is doable, just takes a bit more for some. I have no idea what the year to year differences are, so YMMV.

 

I might tackle the driver side in the spring if the symptoms come back when it gets really cold.

 

Eville Rich

2007 LGT

Edited November 23, 2014 by Eville Rich

I'm in the middle of this job on my 2007 LGT. Everything is almost apart, except for one bolt. I cannot find a good angle/space to get to the passenger side's back-most inner-most bolt.

 

There is the coolant hose in the way, but the real issue are two hoses that have a mesh cover over them. They are not moving and I'm reluctant to force anything.

 

UPDATE: Got it. Just needed to move around the hard lines. Lots of interconnected pieces back there.

 

UPDATE 2: Completed the passenger side. The original gaskets were tough to get out. My guess is that these get a bit more heat due to proximity to the turbo. The driver side was a no-go. The fuel line bracket simply didn't allow sufficient vertical movement to get more that a 1/4 inch or so. I did try to get the gaskets out and the section with the tab dropped much easier than the passenger side. I buttoned it back up. Hopefully the issues were all on the passenger side. Time will tell.

 

While this job can be done in the driveway/garage, it is not a job for a novice. For my '07, that fuel line makes it apparently more complex than others have experienced, though I know others have mentioned it as a problem. I'm just passing this along in case others want to dive in. I think the job is doable, just takes a bit more for some. I have no idea what the year to year differences are, so YMMV.

 

I might tackle the driver side in the spring if the symptoms come back when it gets really cold.

 

Eville Rich

2007 LGT

 

Hey man, I did this job just two weekends ago and I am a very novice car wrencher dude. I had the same issue with the drivers side but I managed to succeed by doing them one at a time and taking it very slow. Use the fuel lines in the centre as a kinda fulcum and rock the manifold up on the front and rear.

(so the rear will be down pressed against the tgv when you're doing the front and vice versa)

 

What I did for the drivers side:

 

pulled up on the mainfold so I could get an allen key (the biggest one I have - just a smidge taller than the new gasket) in where one of the bolts (TGV -> intake) sit at the very front (dont put this between the TGV-intake, only at the bolt hole). I then had just enough room to pick out the gasket and I could put the new gasket on the tgv and use the manifold to seal it in. I used the allen key as a lever to push up on the manifold when I needed more room. Do the same thing for the rear. Its very tight, and I didn't think i'd have enough room because of the fuel lines, but rocking it up allows you to have enough room. You can pull pretty hard against those lines as well. There is enough room.

 

IT CAN BE DONE

Has anyone used gasket part number 14035AA492 on their 05-06 LGT? I'm experiencing a rough idle and RPM drops until my engine is warm, and was looking to replace these gaskets.

 

When I search this part number it looks like these fit on all 4th gen GT's, but several posts here tell me that they don't.

I bought some a few days ago for my '05 and I'll post my results after i get around to installing them later this week. On top of my super-slipping clutch, my car's low idle (and occasional misfire) are driving me bonkers.

I picked up some gaskets today from the stealership as well. I plan on installing them sooner or later when I come back from Kentucky. I'll let everyone know as well. I don't know why these wouldn't fit, in fact I'll be surprised if they don't!

I picked up some gaskets today from the stealership as well. I plan on installing them sooner or later when I come back from Kentucky. I'll let everyone know as well. I don't know why these wouldn't fit, in fact I'll be surprised if they don't!

 

Where at in KY are you heading? I'm in Florence, about 20 min South of Cincinnati. Stop by and we can install them together!

Where at in KY are you heading? I'm in Florence, about 20 min South of Cincinnati. Stop by and we can install them together!

 

If only I had spare time!

 

I pass through there a few times a year, I'm headed down to London, going to visit family for Thanksgiving... and probably visit some nice roads while i'm at it. (Weather permitting )

Just did this on my 07 due to super cold weather here in maryland, and the rough idle and misfire codes. So far so good! Thanks for the detailed post!

I bought some a few days ago for my '05 and I'll post my results after i get around to installing them later this week. On top of my super-slipping clutch, my car's low idle (and occasional misfire) are driving me bonkers.

I ended up putting these in my car a couple of weeks ago and it didn't fix my problem.

As it turns out there's something wonky with one of my injectors (here).

As someone who is both cheap and not mechanically gifted, I have to ask this question.

 

As an alternative to replacing the gaskets, as my 07 LGT is showing the symptoms described in this awesome thread, can I just push in the clutch and give it more gas to stop from stalling? That's what I've been doing the past couple days, and other than looking like a knob at a red traffic light revving his engine, it's kept me from stalling out. It's only at a couple red lights, in that 10 minute window of engine temp from "blue light off & heater just comes on" to "some other point higher on the gauage that I forget to take note of"

As someone who is both cheap and not mechanically gifted, I have to ask this question.

 

As an alternative to replacing the gaskets, as my 07 LGT is showing the symptoms described in this awesome thread, can I just push in the clutch and give it more gas to stop from stalling? That's what I've been doing the past couple days, and other than looking like a knob at a red traffic light revving his engine, it's kept me from stalling out. It's only at a couple red lights, in that 10 minute window of engine temp from "blue light off & heater just comes on" to "some other point higher on the gauage that I forget to take note of"

 

This relieves the stalling symptom, but does not fix the underlying problem, which is that you have air entering the engine after the Mass Air Flow sensor (MAF) at the intake. This means the car's computer (ECU) is always having to correct the fuel added in order to maintain the proper air-to-fuel ratio (A/F) in any situation in which the manifold is in vacuum, which includes idle and cruising on the highway at constant speed / incline. If it is a minor leak, this means you're hurting your fuel economy. If it is a major leak, things get worse because the most your Subaru ECU can correct for is about 15% error in A/F. If you have more air entering at the leak than the car can correct for by adding fuel by this 15% margin, you will be running LEAN at idle, and worse, while cruising. This means there is less fuel than is needed to keep things in the cylinder from getting too hot, which can cause damage to the engine internals over the long term.

 

Even if the stalling goes away after the engine warms up, it is still possible you have a leak all the time but it is not enough to cause an obvious symptom (the major leak "fixes" itself into a minor leak). For my car this showed itself as a stutter while coasting down in 1st gear, like while going slowly down a long hill. I would always have to push the clutch in while trying to do this, even after the engine had been warm for many hours.

 

Long story short: this is a PITA to fix but the parts are cheap. Either turn a wrench or pay someone to do it for you... but you need to fix this problem if it is indeed a leak at the intake manifold gaskets. Good luck!

CWW - thanks for explanation & the warning about not fixing this issue.

 

My car may also displays a "stutter" in first gear at low / no throttle input. I thought it was just twitchy. It is annoying in stop & go traffic for sure.

Just to let everyone know there are other causes for idle stuttering..

 

This happened to me and I changed my O-rings. It did help, but didn't fully solve the problem.

 

I looked for solutions for about a year until my motor definitely had a problem running at idle and low RPM. I took it to the shop for diagnosis. They reported that Cyl 2 exhaust valve was most likely burned but they couldn't see it with a bore-scope, but compression was shot. They tore it open and sure enough, a wicked crack in the valve with a gap burned through it from running over time. The gap was enough that Cyl 2 didn't have compression.

 

They said this typically starts out as a rough idle because of low compression and progresses until the speed of the engine cycle can no longer make up for the loss of compression through the crack as it widens.

 

So, if changing your O-rings doesn't solve it, pull a compression test. If one cyl is low - you're probably looking at pulling the head on that side and a valve job. This happened to me @ 250k miles, so I went with a motor rebuild.

<snip> This happened to me @ 250k miles, so I went with a motor rebuild.

Wow! It's taken me 7 years to do 38k miles. At this rate it'll be 25+ years before I catch up to that kind of mileage. Thanks for the extra info on compression.

Stuttering and off idle stumble can also be the oil control valves. I fought my car for a long time till I changed these. IT's 180 bucks well spent if you have these symptoms. But intake leaks need to be fixed first.

Thanks for this. I had my fuel pump changed which didn't fix the problem. Time to do this. Hope it finally fixes my problem. I've had this problem for years, just getting worst and worst.

I fought it for a year or more as well. The intake gaskets not fixing it was the nail in the coffin for the old OVCS.

'08 here (of course, bought it in July...three months before they changed the gasket design) with 121,500 miles...just changed out the gaskets, car idles great again. But thanks for the tips for the other stuff...would have been scratching my head if the gasket change didn't fix the problem.

Just changed mine out last night on my 07. Idle is still pretty low, after I check my TMIC, I may check my OCV as well.

I did post this on the what did you do to your... thread, but that's moving fast. So back here:

 

Found the cause (one of) of my high A trim. My IM gaskets that I just replaced are leaking on the drivers side, seems to be right at the cross bar/bracket. I have it pulled back up, trying to clean under there but there is no room. Gaskets look to be all seated and I did have it secured flush previously. Any suggestions?

 

EDIT: I saw a vid of an 07 OBXT and it looks like the IM has grooves/teeth in the gasket recess. I would assume the LGT has the same and I wonder if I have it pinched a bit and not quite lined up.

Edited March 20, 2015 by gimpydingo