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Discussion Starter #1
I drive a 2013 si coupe, which has been fairly beat on, by the previous owner and my self for the last 3 or more months. Recently, my mpg went from 25-26 to 17-18mpg. I’ve read that replacing the air filters (not done yet), replacing the spark plugs(not done yet), and running fuel injector cleaner (done but no results, stayed terrible). I’m checking my tires tommorrow and will be doing all these things in the next few days. Is there anything i am missing??
 

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Get back to us once you do the air filter and spark plugs. Both are relatively simple to do. How is it idling?
 

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Truck? What truck?!
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How many miles are on the car? That would help determine the necessity for replacement maintenance items.
 

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Truck? What truck?!
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27,503 Posts

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2012 Honda Civic Si
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I recently bought my Si and ran Techron almost immediately through the fuel and saw no results. I thought nothing of it but my mpg started to decrease rapidly so I tried it again after a thousand or so miles but I did it on a quarter tank this time and forgot to fill up and guess what, mpg shot back up. I’m going to try Seafoam next the same way just for science because I saw a video where a guy experimented with comparing Seafoam and Techron and they apparently cleaned different parts of the engine better or worse.
I’m not super knowledgeable about cars, that’s just my personal anecdotal experience. Also my car is still all stock except a resonator delete (yeah I know, rice AF, but I like how it sounds) so IDK if that affects anything.
 

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Discussion Starter #10
I recently bought my Si and ran Techron almost immediately through the fuel and saw no results. I thought nothing of it but my mpg started to decrease rapidly so I tried it again after a thousand or so miles but I did it on a quarter tank this time and forgot to fill up and guess what, mpg shot back up. I’m going to try Seafoam next the same way just for science because I saw a video where a guy experimented with comparing Seafoam and Techron and they apparently cleaned different parts of the engine better or worse.
I’m not super knowledgeable about cars, that’s just my personal anecdotal experience. Also my car is still all stock except a resonator delete (yeah I know, rice AF, but I like how it sounds) so IDK if that affects anything.
I’m gonna be honest, I have no idea what Techron or seafoam is
 

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2012 Honda Civic Si
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4 Posts
Yeah he definitely knows what he’s doing. I started watching because his video on Costco oil came up on my YouTube and was impressed by his test methods
 

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I Need A Vacation
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13,558 Posts
I lose 2 or 3 mpg, but 8 or 9?
To suddenly drop 8-9 MPG than there is something wrong with his car. I would probably question how he is doing his calculations assuming his driving habits haven't changed.
 

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Discussion Starter #18
To suddenly drop 8-9 MPG than there is something wrong with his car. I would probably question how he is doing his calculations assuming his driving habits haven't changed.
I’ve been driving it the same since I bought the car a few months ago, and am using the little distance traveled and average mpg. I filled up and did some driving in town today and it is at 18mpg. I installed some acuity shifter cable bushings a few weeks ago when the bad mpg started so I tightened up the tube which connects the air box to the engine. My tires were all at different psi so I filled them up to the recommended 32. Air filter tommorrow, and spark plugs next week.
 

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2012 CBP FG4
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284 Posts
Oh yeah. Every morning. I only drive 6 miles to work, but I let the car warm up to at least 140degs before driving as that's the low side temp for VTEC engagement on my tune. So for a 10 - 15 min drive, the car idles for around 3 - 4 mins and I lose about .2-.3 MPG every start up. (at least from a cold start. Obvs a warm start is a bit different)
 
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