Sicktght311

iTrader: (2)

So i went to drive my car today after sitting in the driveway all of yesterday and something is different. I can hear what sounds like a slight exhaust leak. The exhaust tone i had with an open downpipe is there very slightly, and my wideband now reads 14.7-15 for a second or two at idle, and then creeps down to 17. If i rev the car the numbers go back up, but like i said, if its sitting at idle the AFRs will go down to like 17. Sound like i'm leaking air into the exhaust system pre wideband o2 sensor?

Wallesasuaz

iTrader: (23)

yes.... wideband reads accurately and if it's giving you 17, there's definitely leakage before it gets to wideband. But, damn, it has to be a major leak...

I have a narrowband and mine reads at idle, between 14-15. When I rev it goes up and usually just sweeps back and forth. ( Yes i know, it doesn't read as accurate as a WB). But, I'm not tuning, so it's just for flash.

anyways, Have you been messing around w/ your exhaust lately? Maybe a gasket is pinched or gone. Have them all checked.

Sicktght311

iTrader: (2)

Thats the weird thing, Theres def an exhaust leak, because i can hear it, but it has developed literally within just a day and a half of my car sitting in the driveway. I'm going to try to pull the DP off tonight and see if theres any holes anywhere. I'm thinking maybe the weld for the o2 bung for my wideband might be the culprit. It was the last thing welded in there (about a week ago) and perhaps it just cracked or something. Unfortunately i dont have time to bring it to a shop to get fixed until the weekend so i'll see what i can find int he meantime

Sicktght311

iTrader: (2)

Soooo i had an hour or so tonight to take a closer look. I cant find any exhaust leaks, but now i may be leaning more to an air leak. Idle seems to be the only thing affected AFR wise. STartup everything is normal, once everything is boosted and hot it starts. at idle, 2 out of 4 times the AFR will dip down to 16-17 for 3-5 seconds then slowly come back to 14.7-15.3. I guess the ecu readjusting. The other thing i noticed since i took it for a few pulls on boost is although the AFRs under everything except for idle read normal but the turbo seems louder than before. I can hear it sucking in air earlier and harder and under full throttle full boost there is a large hissing sound, like (duh) an air leak. I checked up and down the entire Intake side and there is no way any air is getting in through any leaks, so that leaves me to believe it is boost side. Would a boost leak cause a minute amount of air to be sucked in during idle causing a temporary leaningout, but still retain full boost and correct AFR's at cruising and WOT?

Wallesasuaz

iTrader: (23)

If you had a leak, wouldn't air only come out? I don't think it would be possible for air to come in unless the car would just fall into vacuum. Tough question.

Sicktght311

iTrader: (2)

Well under idle you are at vaccuum. So yeah, air sucks in during idle and cruising, and is forced into the car during boost, and pushed out of the pipes.

Sicktght311

iTrader: (2)

So it turns out its a definite exhaust leak. I took the car for 10 mile drive today and within that 10 miles the exhaust got louder and its a definite leak somewhere between the turbo and the cat, most likely before the 02 sensors. I had a custom downpipe made after i turbo'd the car so i'm hoping its just a faulty weld or a gasket blew out. bringin it back to em thursday to check it out

rice_rocket88

iTrader: (9)

You got a flex pipe? Maybe there are some threads that have deteriorated.

Also don't know your setup, but there could be leaks in the manifold, the manifold to turbo, and the turbo to downpipe. Worst case is a warped flange, but you still should see some soot where the leak is. Unfortunately it's not winter or you could take a peek on startup and watch the smoke puff away.

Sicktght311

iTrader: (2)

Yeah i dont see any major soot building up any forward facing flanges, i'm dropping it off to the shop that made my downpipe thursday and i'm gonna let them throw it up on the lift. If its a faulty weld on the downpipe then they can fix it for free since its their fault, if its a loose flange or dead gasket then i'll do it myself

Sicktght311

iTrader: (2)

So its the gasket between the manifold and the turbo, tons'o'fun. I ordered a replacement gasket offline today, hopefully have it by tuesday in time to drain the coolant, and completely take the turbo off the head. At least it'll give me a chance to tighten up some oil fittings and clean the thing up. Pain in the ***

SLVROZ_03

iTrader: (10)

Glad to see you found the culprit !

rice_rocket88

iTrader: (9)

Dang, it must be a pain with the Oz... I figured that that gasket is also easy to replace, at least on the DSMs and the Evos.

Crank 4 bolts holding the O2 housing and slide the gasket out.

Good that you found it though, I'm sure you'll be boosting much happier!

Sicktght311

iTrader: (2)

Its not the gasket on the 02 housing. Its the gasket between the Manifold and the Turbo, so i gotta unbolt the turbo from the manifold, which means i gotta unbolt the downpipe, the intercooler pipes, the oil inlet, oil outlet, the water lines, and at that point i might as well unbolt the whole manifold from the head and clean everything up. PITA but whatever, i'll just put the car in the garage for 2 nights next week

Wallesasuaz

iTrader: (23)

basically take the whole turbo assembly apart...

sucks

Wallesasuaz

iTrader: (23)

hey Sick, how far in long island are you?