Premium or Not?

R

RACER-X

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Hi Guys;

My dealer and the gas cap says Premium Unleaded only. I just picked up an 09 AWD FX35. I know theres legitmacy to this but what can go wrong if 89 is used vs. 92.

RACER-X
 
89 is OK, 92 is prefferred. Most here run premium. Cali 89 knocked on mine when it was stock. I'm tuned now, so there's no choice but 91 & up.
 
Running regular will not hurt your car. But you will lose some performance. If you want to run at optimum levels use premium.
 
I was noticing a loss of power and MPG's. While gas was around 5 bucks a gallon I was using regular and didn't have any knock issues but the dealer told me that low octane fuel can cause injectors to become dirty.

I ran some injector/fuel system cleaner through a couple of tank fills and checked MPG over three weeks of driving around town,up and down the mountain,and on freeways now I'm back up to 18.6 MPG from 13.2 MPG

So I'm only running premium now and adding fuel injector cleaner at around same interval as oil changes.
 
you will actually lose mpg when going lower than 91 ... and in the end 91 or 93 comes out to be cheaper trust me see it urself and do 1 tank of 89 and do 1 tank of 93 and seee the result
 
Pupp said:
Running regular will not hurt your car. But you will lose some performance. If you want to run at optimum levels use premium.
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I ran the next level down from Premium once and my car started to knock. I can't speak for what you should or should not do, but that's what happened. I took it to the dealer and he said, USE PREMIUM.
 
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MTN FX said:
I was noticing a loss of power and MPG's. While gas was around 5 bucks a gallon I was using regular and didn't have any knock issues but the dealer told me that low octane fuel can cause injectors to become dirty.

I ran some injector/fuel system cleaner through a couple of tank fills and checked MPG over three weeks of driving around town,up and down the mountain,and on freeways now I'm back up to 18.6 MPG from 13.2 MPG

So I'm only running premium now and adding fuel injector cleaner at around same interval as oil changes.
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Bro when ever you get a chance try cleaning the body throttle.. The fact that we used cheap fuel got it dirty. I know my fuel injector are clean but not the throttle. My first incident happened today. I have to do a major cleaning to it now.

---------- Post added at 04:08 PM ---------- Previous post was at 04:05 PM ----------

You have a 09 and you are asking what fuel you should be using?

Use 89 and tell me what happened!(jk)

93 and up if there is any!
 
gto said:
FYI, Be real careful with the TB. You get it outa wack & it's gonna need a consult reset. Trust me
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Thanks Dave I read your post too about being really careful while doing this.

---------- Post added at 05:08 PM ---------- Previous post was at 05:03 PM ----------
StuLax18 said:
Why would using regular fuel make the throttle body dirty? They aren't connected...
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Odd there was recidue in there that seeing to be carbon deposit..

So my question is.. I know dust gets in there but we put filters for that reason. So where did the carbon residue come from?
 
gto said:
FYI, Be real careful with the TB. You get it outa wack & it's gonna need a consult reset. Trust me
Click to expand...

gto said:
Carbon buildup is normal. If it aint to bad, just leave it
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I cleaned my TB when I removed the upper plenum (MD spacers install also painted the plenum). I didnt have any problems moving/cleaning the butterfly, as long as you make sure its in the same position (closed) when you plug everything back in and start the motor.

there is a throttle position learn procedure here.
///799

I think cleaning the TB is a good idea because, left alone, you may experience the problems members had (hard starting, wont stay on, irregular idle). Of course work on this at your own risk.
 
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