So, I've been trying to figure this out for a little bit, but I'm stumped.

My car is seven years old about 126K on it, but it sounds bad when idling. It sounds like it might stall out or makes puttering noises I guess you could say. I have no problem with power and it still drives good.

I have done all the following: cleaned MAF, cleaned throttle body, did all pedal resets (car idles between 600-700), re-torqued plenum, replaced a lot of rubber hoses with silicone (some were frayed), and put NGK iridium plugs in.

The only thing I can think of now is maybe taking the fuel injectors out for cleaning. I also noticed the sounds don't even sound like they are coming from the engine. Mostly towards the middle and back of the car. So, I was thinking maybe cat, O2 sensor, or something but I have not gotten any type of CEL.

I also heard a faint hissing sound coming from the master brake cylinder and brake booster. I'm thinking that might be a leak, so I'm awaiting a new mbc and brake booster just in case. My brakes work fine, but bought these parts just in case.

Anybody have any ideas?

 

After my plenum spacer install I forgot to install a vacuum hose beneath the TB... Check that mate because sometimes the simplest things are the answer. Also, the oil fill cap has a rubber ring around it. Check if it got lodged under the plenum.

 

an exhaust leak maybe? id lay under the car while its running and see if you can hear leaks from behind the headers(from the cats on back) exhaust holes would cuz puttering. does it sound weird when you rev it up in neutral as well? like a tingy can sound?

 

It does sound kind of weird when I rev it up from neutral or park. I was thinking it might be an exhaust leak also. It kind of reminded me of those Hondas you see that sound like a coffee can is attached to the exhaust, but nowhere near like it. It definitely doesn't have the G sound anymore that I love though. Wouldn't an exhaust leak cause some kind of trigger though or is it probably to minor for the computer to pick up on it?

 

Exhaust leaks can be tricky to diagnose by just listening. They can sound completely different depending where they are in the exhaust trail and what kind of exhaust system mods you have. I've had quite a few and they all sounded different, some I couldn't hear but found them while troubleshooting other noises. And I don't think there is any sensor that would pick up an exhaust leak specifically. Best bet is to get under there and take a good look.

 

I did a 10 dollar smoke test and purchased some SeaFoam, lol. I jacked up my G sucked in the SeaFoam through the brake booster line. So much smoke came out from the flex pipe it was ridiculous.

 

You can try plugging the vacuum port that feeds the master cylinder to see if the car idles better.

 

I vote exhaust leak.

I had similar symptoms with my car. Tossed it up on a lift and found this



If you take an old t-shirt or rags and stuff them into the tailpipes, you can then easily find exhaust leaks.


To find vac leaks, spray a little bit of carb cleaner in the area you suspect. If there is a leak, idle will rise slightly

 

I do have an extremely bad exhaust leak at the flex pipe on the driver's side. I put some SeaFoam in through the brake booster and it was pouring out there. I ordered a Megan Y-Pipe and will be installing that when I get a chance. Hoping this is the only issue I have.

I tried the carb cleaner and didn't really notice idle change at all. I'm going to make a DIY smoke machine when I have some time.

 

Well, my car sounds 98% better, lol. It was definitely an exhaust leak and I had several; I got the V2 Megan Y-Pipe which is based off the HR style. When I attempted to install a few days ago my mid-pipe was shot. All the bolts were rusted and liquid wrench didn't help and they stripped with one turn. I put in order at Advance Auto for a Walker resonator, but the same day found someone local selling their mid-pipe, so I picked it up for 80 bucks and the reviews I read here were hit or miss. Advance Auto said they will give me a refund, so I'll find out on Wednesday.

I jacked the G up and whipped out my Sawzall and cut that bitch out! I now have another dilemma involving my muffler. The flange is full of holes and one of the bolts came off when I turned the nut. I might reach out to that guy I bought the midpipe from, since I think he has a muffler for sale and several other parts. I was thinking of just getting rid of the flange and having a small straight pipe welded in though also depending on price.

The grounding wire also just literally fell of and it looks like there are two wires that should be grounded, but now I have none. Anyone know of a decent place to re-route those wires?

My car sounds so much better though and I'm not embarrassed to drive it around, lol. Still have a little bit of a coffee can noise though towards the end of the car, so I want fix the muffler ASAP. I'm pretty happy with the Megan pipe though and would recommend it for someone who needs a new Y-Pipe, but just make sure you keep all your old nuts if you still have the OEM CATS! The nuts and bolts they give you are 17MM and don't fit on the stock CAT bolts.

 

Some pics.

 

how much is a exhaust leak fix ? I have the bottom of my 2010 G37XS leaking. Not sure what it is

 

Take it to a reputable muffler shop, most of the time it's less than $100 if it's just a cracked pipe they can weld up easily.