not only are the gas prices so high i use premium only on my 06 mcs. the car drive fine its completly stock. i checked all the filters, oils, spark plugs, and wires and everythings fine. i dont drive fast and its the 6 speed manual i shift between 2k-3k. guys give me a hand?

 

how long are your trips? do you only do city driving or highway driving? mixed? I try to keep my trips 50/50 and not make short 2 mile trips. I'm getting almost 30, sometimes 31 if I really baby it

 

i do mixed driving almost 50/50. but it feels like the car has no power. it eats gas like crazy.

 

Down on power and poor fuel mileage; sounds like a good time to have it looked into at the dealer/shop.

 

did you check tire pressures?

Cheers,

Charlie

 

after 3k rpm's the power kicks in it feels like i have a dang vtec at 3k!! and the car has never been modded.

 

your sig shows cia and exhaust mod


my mpg went down when i installed a cia and less restrictive exhaust

 

Brakes dragging? Feel wheels (gingerly) after driving to see if one is much hotter than its opposite. Parking brake dragging could also be an issue.

 

I took off the cai and went back to stock thinking it might of been the problem but its still the same. And I did the one ball exhaust mod but its still the same.

 

There ya go - that vtec feeling consumes gas. On my '06 MCS auto, if I shift around 2200 rpm (boring, I know) I can get 33-35 mpg. Mostly I average around 32. 21 is terrible - check tire pressures, O2 sensors, etc. Good luck!

 

Check the supercharger bypass valve to see if it is closing all the way.

Ken

 

Around town, that is about what I used to get. Highway I could get 25mpg, but I was low twenties all the time (calculating gallons vs miles on trip Odometer)

While at the RMW tune, I saw how pig rich my car was running. It is thought the previous owner put in a higher pressure fuel pump which would have done that, but I can't say for sure.

Anyway, the entire process of dyno tuning is to get the fuel/air mix perfect with no waste. Believe it or not, a dyno tune would probably give you more power and better fuel economy (assuming you drove the same way...)

This is not really helpful, but I figured I would post it. I just filled up today after a tune Monday (wacky wednesdays - 10 cents off premium) and it will be a while before I need a refill and can say anything definitive.

 

Iv heard about the r53's bypass valves leaking how can I make sure its not?

 

You will need to remove it and take a look at the plate inside to see if it is fully closed in it's relaxed state.

 

ok, so i went ahead and romoved it. its leaking.

 

The good news is.. it's a relatively easy and not so expensive fix. Your mpg should get right back up, not the mention the lost power.

K

 

how would i be able to fix it? i had an r56 so im kind of new to the SC world.

 

All you do is replace it, usually the spring that closes it disintegrates and there isnt anything you can really do from there.

 

Even though I have an R56, this is good info!

 

I work at my fathers mechanic shop so they have springs laying, around do u think I can swap one in?

 

springs are springs - but I'd be mighty careful to match the rate, free length, and diameter. if 'twas me I'd use the OEM part just to be sure.

close enough might not be...

 

I see, because I really can't afford 110$ for a bypass valve at the moment. Im just looking for a diy fix.

 

Sorry for reviving this, but i have an 04 MCS and my gas mileage has fallen rather sharply.. It runs great, but is using more gas.. Could this also be a bypass valve?

 

You could try, but if you screw it up, you will be without a car until you can fork out the $110. ALso, your gas milage is not uncommon and I don't suspect that a good bypass valve is going to drive it up that much, maybe 1 or 2 more MPG. My guess is that living in the Miami area you are doing a lot of stop and go which will eat gas.

On that last note, if you are worried about fuel, I would seriously considering dumping any future mod ideas. None of them will increase your milage and that 19% in Miami heat is a bad idea.

 

Im also having the same problem, but with a P1498 unmetered air after compressor code, and the EML light on....ive searched high and low for a vaccum leak, changed quite a few parts all with no change....could it be the bypass valve?