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      01-19-2010, 10:05 AM   #9
eg3
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Drives: X6 35i
Join Date: Jul 2009
Location: Boston

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Quote:
Originally Posted by audioquest View Post
I did read. But it did. May be it is not a proper Hartge exhaust, I dont know. All I know is that it take a lots of effort to move the car after the change. Anyway the problem is solve after the tunning. But have to admit the high end is very good.
It might be that you've experienced the similar problem others did: When you get a new exhaust, it disables the valve at the rear muffler but they generally forget to plug the tube that goes into the other part in the body. Basically, whenever you disable that valve, you have to make sure that the tube that goes into that has to be closed off. I believe the ECU thinks that the valve is not opened when you hit the accelerator and limits/delays the power.

In my previous SUV (Infiniti FX35), I've done a complete exhaust except the cat converters. Even with larger-than-necessary tubing & very free-flowing mufflers and even that was a naturally aspirated engine, I didn't feel any noticeable torque loss. Since both you and Henry experienced the same thing, I believe this is an ECU issue (Engine computer), not an exhaust issue.

I've looked at Henry's exhaust pictures and it looks perfectly fine and he only changed the tips, nothing more but felt the same thing which even supports that it's something with the valve. I believe with the tuning you had, they disabled that feature for the valve which helped you out on the low end loss.

I seriously don't want to be a "I know everything, you don't know shit" guy but from experience, I can say that a 2.25" - 2.5" exhaust like you have won't affect the low end torque. You should be even better with it in fact. Also, I'd be very curious to see if you could take a look at that hose and plug it up. I bet you'll even gain some grunt at the low end with that. Here's a pic on that:



It's the same valve control unit that you disable with the golf tee mod. When you change the exhaust, the valve goes away but the hose is still there, plugged into the ECU through that unit you see there. If this hose is not closed, I think the ECU experiences some issue.

Ege
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