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problems after header install

yzboy85

yzboy85

New member
I just got done installing SD headers in my car and have noticed about a 4 mpg drop from what I would normally expect to be seeing. Is this just something I have to live with, maybe something to do with being catless, or is something else going on?
 
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Re: mileage drop

Well, the only code shes throwing is for my bad maf which has been bad for a while now and hasn't affected my mpg before (replacing it later this week hopefully). Other than that she does have a leak which I haven't addressed yet (thinking its the res flange). how do I go about diagnosing this? I have torque app and can read anything needed

Also, I'm seeing about the same amount of kr as I did with stock exhaust....I'm guessing I didn't make enough room for the front o2 (banged it till there was about 1/2" clearance) and its false? from what I've read I should be seeing 0 kr on a stock engine with headers
 
Re: mileage drop

I still see a couple degrees with CAI and Speed Daddy's on 91 octane. Stock pulley. I'm about 99.9% sure it's legit knock.
 
Re: mileage drop

How many is a couple? I'm seeing like 3-4* at WOT which is what I was seeing with the exact same car on stock exhaust, I would think it would at least be less
 
Well there's still a chance even with headers that you'll still see knock. Now some things to double check is that the headers aren't hitting anything causing false knock and that your motor mounts are still in good condition.
 


Re: mileage drop

yzboy85 said:
I'm seeing like 3-4* at WOT...
Click to expand...

Same here. Lower motor mount, torque thrust mount and dog bone bushings are all brand new.

I think mine is due mostly to 2 thinks though...
1.) Stock tune
2.) 91 octane

Sorry, didn't mean to hijack. Just wanted to throw my personal experience out there.
 
lower mounts recently got replaced with solid rubber ones a couple of months ago, the only things I could imagine would be hitting are the tranny dipstick or the front o2, both of which I tried to address when putting them in like you're supposed to (bent the dipstick a bit, hammered some room for the o2) but maybe I'll have to go back and try to make some more clearance. not really sure how to test to see if they're hitting other than just trying to rock the engine?
 
I was thinking of having someone torque brake it? If rocking by hand is the test, then I'm good. That thing doesn't move by hand. FWIW, I hammered enough room between the footwell and the front O2 to slip my fingers between. 1/2"? I know it's enough to actually get the sensor in and out without removing the headers or moving the engine.
 
Disconnect the Boost bypass actuator solenoid to and do a few wot runs and see if you still have knock.

Just pull the little plug from it.
 


solved the mpg problem....

unplugged my bad maf sensor and suddenly I'm seeing amazing mileage, baffles me why that made a difference cause it never affected my mileage before but whatever, im seeing like 35mpg cruising at 60 and can't complain about that
 
And here i was thinking i was the only one who name my car after an actress...lol mine is after Stacey Dash
 
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