Exhaust Leak in engine bay

[Cool_Etahn]

Car: 2004.5 A4 1.8T 6MTQ

I have noticed an exhaust leak somewhere in the engine bay on the passenger side of the car near the back of the engine. Also recently especially since the weather has been cooler, cold starts are very erratic with rpm and vacuum fluctuation. I have checked the manifold and down pipe connections they are all solid. What else is around this part of the motor that exhaust travels though? I'm tired of breathing exhaust fumes in the cabin.

[vinny.dtw]

Your best bet really is to poke your hand around the manifold, test pipe, downpipe area to see if theres any air blowing out when you first start your car, so everything is still semi cool, and you can feel moving air, rather then heat. I'd also check UNDER the car as well, as it could be as easy as just one minor gust to blow everything into the engine bay.

Are you still on stock manifold, cat?

[Cool_Etahn]

I did just that this morning... No the car is an APR STG3+, the leak is on the back of the head i am sure of that. I was looking at my bentley manual and I am thinking that the combi (EGR) may be leaking from somewhere. If that's the case, would this cause and erratic idle?

[old guy]

It very well might since it will change the exhaust gas mix a little going past the front wide band O2 sensor.

[vinny.dtw]

If you think it's in the vacuum system, your best bet is just to do a boost leak test, or do a smoke test to find a leak. Any leak in the vacuum system can cause erratic idle. So go ahead and check that out. good luck!

[Cool_Etahn]

well, I just pulled 2 codes from the car. Not sure why these didn't throw the mil though.

16621 - Manifold Pressure / Boost Sensor (G31): Signal too low
P0237 - 002 - Lower Limit Exceeded - Intermittent
16490 - Manifold / Barometric Pressure Sensor (G71) / (F96): Implausible Signal
P0106 - 008 - Implausible Signal - Intermittent

This is not what I wanted to do this weekend.

[Duchenbagen]

If it's the kombi valve that thing looks like a pain in the ass to get to. I just ordered a block off plate for the SAI. Not looking forward to the install.

[Cool_Etahn]

Alright guys, I have been seating here and other sites. What is the easiest was to remove the combo valve? I see in ETKA that there is a manifold for the combi valve. Is it easier to remove the whole unit? I'm wondering how to attack this thing from the top or the bottom of the car? Also, this thing is quite pricey around 200 bucks. There is a cheaper way to go from 034 motorsports with an SAI block off plate. Will removing this system from the car harm anything else except for the environment? I know thats a lot of questions, but thanks for the help...

[old guy]

I removed mine when I replaced the rear coolant flange just to make things easier to get to. It really wasn't too bad. It helps to remove the air box so you can have more room to maneuver around the side. A small mirror helps to see what's back there. You will probably have a permanent CEL from disconnecting the SAI cold start function. If you are running a cat it may shorten the life just a little.

Edit: Here's a pic as to what you are removing. Remove the three bolts holding the combi manifold to the block. Then after you pull the unit out you remove the two bolts and separate the valve from the manifold. Ignore the red notations. They are part of the DIY for the rear coolant flange.

[Cool_Etahn]

Fletcher, Thanks for the info. So just to clarify, unbolt the manifold from the bottom and pull it out from the top?

[old guy]

Fletcher, Thanks for the info. So just to clarify, unbolt the manifold from the bottom and pull it out from the top?

I undid it from the top. I removed the air box, kinda stretched out over the motor and reached around the riders side with a small ratchet to remove the three bolts.

[Cool_Etahn]

Sounds great, thanks again.