Exhaust leak

[Ultimatedsm]

Hey how are you guys doing? My car has been very loud lately, kind of sounds like a mini diesal truck. I went to the track and managed to pull a 14.4 at 91 mph. My car felt really slow and the boost was set at 10 psi but would hit 15 psi at redline (Creep). My mods are:

FMIC (26x12x3) side to side /w 2.5 inch piping
T-clamps and 4 ply couplers
HKS Mega Flow intake
1G BOV
3 inch turbo back exhaust with 3 inch high flow cat
DSMLINK
14B turbo with the JDM 6 bolt
Tein SS suspension


My logs seemed good as well, got 18 degrees of timing at redline which isn't too bad (Haven't tuned it yet, there was zero knock).

Anyway, today I installed my t-clamps and 4 ply couplers, no more blow outs , and when I started the car, I noticed the loud truck noise was coming from the exhaust manifold/o2 housing area. I put my hand right infront of the o2 housing connects to the turbo and I felt a lot of air rushing out. I reved it and even more air was rushing out. Well, that explains my shitty performance. I think the bolts that connect the o2 housing to the hot side of the turbo came loose a bit, and one of the turbo bolts from where the exhaust manifold connects to the turbo was loose as well (You can turn it with your hand).

I am just wondering, what kind of performance loss I might of gotten from this stupidness. Thank you guys,

Ultimatedsm,

 

[JBDdsmer610]

My buddy just had the same problem he took it to get dyoned and he was at like 260 and that was the second time he got it dynoed. the first time he dynoed it ity was at 286. then droped to 260 with an exaust leak he fixed it and kno hes back to about 280 he has almost the same mods as you

 

[Ultimatedsm]

I also noticed when the gas pedal is on the floor, the throttlebody doesn't open all the way. There is still a 1/4 of an inch to go. I think I would of had a better time if these things were fixed .

 

[No_Skillz]

Exhaust leak post turbo won't hurt your performance. You put your hand there next to fresh exhaust gasses and it's not barbecued? Throttle body cable can be adjusted: follow the cable to a bracket behind the intake manifold, has two bolts on it.

 

[Ultimatedsm]

Well if I did burn my hand, I would warn you guys not to do it. However, the car has been sitting for 24 hours and started it. I then checked for leaks etc. I don't recommend doing that when the car reaches its operating temperatures.

The exhaust leak was right at where the turbo meets the o2 housing. So I know I was losing power.

 

[No_Skillz]

The exhaust leak was right at where the turbo meets the o2 housing. So I know I was losing power.

Can't be. Exhaust has already gone through the turbo, past the blades. Where it goes after that doesn't matter. As a matter of fact, a big leak will reduce back pressure, possibly increasing performance. However, there is the possibility that your leaking exhausts are making your engine bay hotter 'n hell, increasing your intake temps, melting your fans, and heating your coolant.

 

[Ultimatedsm]

I don't have the AC fans in there. Coolant temps were a constant 196 F maybe 206F at WOT. I did notice high intake temps. There were around 100-110F. Temps out side were around high 80's to low 90's.

Thats weird, I thought a leak between the turbo and 02 housing would hurt performance. Well one of the bolts where the exhaust manifold connects to the turbo was completely loose, this has happend a few times and I have tightened the to spec everytime. Weird.

 

[funkbuster]

I would guess a pretty good loss seeing as the turbo uses the exhaust to an extent, and if the exhaust never makes it there, you are loosing something.

 

[No_Skillz]

I would guess a pretty good loss seeing as the turbo uses the exhaust to an extent, and if the exhaust never makes it there, you are loosing something.

O2 housing is post turbo. Ultimate, fix that throttle body problem and see where that gets you.

 

[Ultimatedsm]

Well, I noticed a little my fuel trims were off, thats probably due to the leak before the o2 sensor and that is definetly hurting my performance right there. Lesson to all, if the leak is before the o2 sensor you are screwed somehow and need to get it fixed. In additional, yeah sure there is less back pressure, but it has poor airflow characteristics, or its not smooth etc, which again hurts more performance.

 

[jumpfroggy]

I don't think a leak post-turbo (pre-o2) would not affect the turbo that much (aside from the slight "dump tube" effect, lowering backpressure). However, wouldn't this affect O2 readings? And that's why the fuel trims would be off... ECU reads more (or less) O2 because of the leak, then compensates and screws stuff up.

 

[shadowdrag]

Yes, that leak will hurt ## performance. My car is doing the same thing, I used Seafoam and idle the car at 2k. Smoke blew out from between turbo and o2. also, my data log tells me that when boost bulds up, I am running pig rich. My performance went down hill, so I had to turn my boost down to stock until I fix the leak.

I just order a new turbular o2 housing with complete gaskets, hopefully my car performance will be back to normal after I install it.

 

[No_Skillz]

Good call on the O2. I didn't think of that.

 

[jumpfroggy]

shadow, out of curiosity where are you getting your tubular o2 from? I'm trying to plan out what parts I'm going to put on my FWD (modest tuneup, until I get my AWD and go nuts). I'm looking at first doing the O2, downpipe, and exhaust.

 

[spyderturbo007]

Well, I noticed a little my fuel trims were off, thats probably due to the leak before the o2 sensor and that is definetly hurting my performance right there.

You won't notice any performance change between a dead O2 and a working O2. The O2, along with the FT's, are only used by the ECU at cruise and idle. They have no effect on the WOT performance of the vehicle. The jacked O2 sensor signal, resulting from the exhaust leak, will only screw up your gas mileage.

As said above, I can see the performance being effected from the added heat along with the possible recirculation of the exhaust gasses back into the intake.

 

[shadowdrag]

shadow, out of curiosity where are you getting your tubular o2 from? I'm trying to plan out what parts I'm going to put on my FWD (modest tuneup, until I get my AWD and go nuts). I'm looking at first doing the O2, downpipe, and exhaust.

I went into a 2.75" inlet DP and my ported O2 housing flange hardly fits. I had to use Alen top style screws to bolt the flanges together. So when ever I take out the DP, its a Biatch to bolt it back up to the housing. So I just order one right off of this site, I know its pretty spendy, but try Ebay. A buddy of mine bought an Turbular and DP off of SSAUTOCROME and its stills perform very well for 2 years now (still a 12 sec car), so I would go with ebay stuff if you low on cash. But, if you need a ported one I can offer you mine for cheap, it was ported by SlowBoyRacing. This O2 housing housing will be out of my car by next week. 30+shipping its yours.