Possible previous exhaust leak damage?

[stlgrym3]

I’m working with Delicious Tuning on my ACE header and flex fuel tunes. Right now I’m getting revisions on petro since they want to get that part done before moving onto ethanol. I’ve been told by the tuner the last couple tanks of gas have performed sub-par. I’ve used two different brands in those two tanks. Then we brought up the possible exhaust leak from my previous header setup. I’ve only driven less than 1000 miles on the previous setup. Is it possible the damage left by that exhaust leak is causing the car behaving poorly rather than the gas?

By performing poorly I meant the numbers from various logs after each revision, tuner did say it’s getting better however.

[cjd]

What damage? Did you clean things up before installing?


Check all the joints in your Ace also.

[stlgrym3]

Installation was done professionally by a shop.

[RJasonKlein]

@stlgrym3 I’m not clear on what you suspect may be the problem. I have an ACE 4-2-1 Type-A 350 header with a Delicious Tuning ECU reflash and @sales@delicioustuning.com definitely knows what he’s doing. It sounds like he saw something he didn’t like, but what exactly was the problem? Is your car pulling timing or do the logs not look strong? What kind of ‘damage’ was done with your old header due to an exhaust leak?

@cjd makes a great suggestion to make sure all of your exhaust bolts are tightened properly - both he and I had our header bolts loosen on the flange between the header and the secondary collector/overpipe, so you should check yours, too. I can imagine a scenario where loose header bolts could cause erroneous readings by the O2 sensor, which may affect the ECU and and your data logs.

[Irace86.2.0]

Sometimes an exhaust leak can cause a rich condition that can foul spark plugs and o2 sensors, which once fouled, they will cause problems.

[stlgrym3]

Originally Posted by RJasonKlein

@stlgrym3 I’m not clear on what you suspect may be the problem. I have an ACE 4-2-1 Type-A 350 header with a Delicious Tuning ECU reflash and @sales@delicioustuning.com definitely knows what he’s doing. It sounds like he saw something he didn’t like, but what exactly was the problem? Is your car pulling timing or do the logs not look strong? What kind of ‘damage’ was done with your old header due to an exhaust leak?


@cjd makes a great suggestion to make sure all of your exhaust bolts are tightened properly - both he and I had our header bolts loosen on the flange between the header and the secondary collector/overpipe, so you should check yours, too. I can imagine a scenario where loose header bolts could cause erroneous readings by the O2 sensor, which may affect the ECU and and your data logs.

The exhaust leak was brought up by Zach of DT when we were communicating back and forth on the possible reason why my car is “under performing” (his words). My previous header did have some issue with the gasket bolts that might’ve caused exhaust leak. At first we were suspect maybe a bad tank of gas caused the sub-par logging data, but then again I was on a second tank of 91 (2 different brands) since the header install because they suspected the first tank was bad. We don’t know whether the exhaust leak is the culprit but that’s one possibility. But Zach told me he does see improvements on each revision I’ve done so far, so hopefully we can finish the pump gas portion of tuning soon and move on to the ethanol tuning.


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[steve99]

As long as its not leaking now its fine.


If its still leaking it will cause issues isually at lower rpm, will result in high ltft or if using ecutek closed loop fueling high correction values.


Its probably just bad fuel

[mswbrz]

So I have your same setup in terms of header and tune , mine has the jrsc too. Just took my Brz to dealer for a different issue & they said I have a rear exhaust leak , I don't notice any performance issues or lag in the lower rpm. Is that what your noticing with your leak ? What is is the fix for the rear exhaust leak; would it just be new flange gaskets for the rear ?


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[mswbrz]

Originally Posted by RJasonKlein

@stlgrym3 I’m not clear on what you suspect may be the problem. I have an ACE 4-2-1 Type-A 350 header with a Delicious Tuning ECU reflash and @sales@delicioustuning.com definitely knows what he’s doing. It sounds like he saw something he didn’t like, but what exactly was the problem? Is your car pulling timing or do the logs not look strong? What kind of ‘damage’ was done with your old header due to an exhaust leak?


@cjd makes a great suggestion to make sure all of your exhaust bolts are tightened properly - both he and I had our header bolts loosen on the flange between the header and the secondary collector/overpipe, so you should check yours, too. I can imagine a scenario where loose header bolts could cause erroneous readings by the O2 sensor, which may affect the ECU and and your data logs.

Rjk, did your headers make any rattling noise when the bolts were loose in on the flange and over pipe ? How did you know they were lose ?


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[cjd]

Originally Posted by mswbrz

Rjk, did your headers make any rattling noise when the bolts were loose in on the flange and over pipe ? How did you know they were lose ?


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I occasionally heard a noise that was probably the leak and I assumed was just thin header walls... Discovered it when I went to install a new front pipe. I had a leak on my last BRZ and it was as @steve99 said, and obvious in the logs. It may be less obvious because the sensor is on the side that still had a stud, but I also had a suspected bad tank of gas.

[Breadman]

Talking about leak, why is.that weird double threaded post and a nut used and not a nut and bolt?


But I too had it back.out.some and make a leak at the merge

[Irace86.2.0]

The other thing that can happen with an exhaus leak when/if it goes rich is damage to the cats. The thin metal can melt and get gummed up. It happened to me but I was running rich on my Supra for a while before I noticed. Just saying.

[RJasonKlein]

Originally Posted by mswbrz

Rjk, did your headers make any rattling noise when the bolts were loose in on the flange and over pipe ? How did you know they were lose ?


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My car was fine on the beginning of a short ride home one night and minutes later it wasn’t. There was no rattling or noise, but as I pulled in the garage it was obvious there was a leak somewhere - in a matter of minutes the exhaust had gone from sounding great to becoming totally farty and bloated.

[stlgrym3]

Seems new tank of pump gas is behaving better according to Zach.