so i have noticed that on my 2007 SS/SC with GMS2 i am only getting on average around 19 city. now i drive pretty averagely and don't romp on it to often, once a week or so. i just dont understand what it could be, is this normal? i have changed the oil, air filter, spark plugs. could it be my high altitude (3,500ft) and cold weather?

 

Are you running rich at all? What are the spark plug gaps?

 

I find it amazing you guys actually get more than that with city driving. I average 26.3mpg on the highway cruising at 80mph and 19-20mph city.

 

Stop and go kills mpg's. How often are you on the highway compared to city driving?

 

it doesnt feel like it, no codes are being thrown, gaps are 0.035', mostly all city

 

How are the conditions of your tires?

Do you check the air pressure regularly?

You only romp on it once a week? Whats the fun in that, lol.

 

I say it's because of city driving. Im glade I live in the country and only drive country roads and highways. So I'm always adv. 29 but one time when I drove down town DC and sitting in traffic for an hour it went down to 24 mpg. So I could only imagine if you drive In the city everyday

 

I usually get in the 21-24mpg range in mix of 70% city/stop and go and 30% highway.

 

Same here.

 

Around 20 city 30 hwy is normal.

 

Averaging 20.7 right now on the DIC, changed my o2 switching voltage from 500 down to 425-450 in hptuners, which helped bring it up above 18.5. lol Havent tested it on the highway yet, just been workin on making corrects to what it did to the maf scale.

 

I'm down to 300mV in the lower zones here. Works like a charm. Nice consistent AFR switch at cruise. Plus or minus .3 points from target AFR. Also halved prop airflow and swapped stoich for 15.0. No KR or excessive heat. Then again I'm not boosted... yet.

 

Hesitant to change the stoich for AFR because that effects every table in the tune that relies on knowing what stoich is for gasoline. Hear alot of guys on LS1tech running 375mv with no issues, might drop it down a little bit more see how it does.

 

I'm an 06 and i don't get more than 20 in city (80% of my driving) with very few pulls and fairly light footed. it sucks. but then on the freeway i average between 29-32 so it's a weird balance, because that's higher than reported for these if i remember right

 

I can because I'm N/A and don't have to worry about blowing up. Power Enrichment gets really interesting. But everything is ironed out now.

 

I'm also N/A

 

Really? For some reason I swore you were a boosted guy. Oh well. You'll be fine with a changed stoich if you ever decide to. I have to command 12.5AFR to actually achieve 13.0AFR, which is my car's sweet spot. My PE table looks like this:



Maybe I should start another thread???

 

I dont have a wideband to verify the AFR's yet so I dont play with the PE EQ ratio, only try to keep the o2mv around 865-875mv when tuning WOT until I have something that can actually tell me where im at exactly. With the longtube headers and no cat I presume the o2 sensor element runs a little cooler then stock so I use a reference of something similar to this. It's a ballpark measurement, that I just go by how the car feels. Stock WOT o2mv is somewhere around high 700s low 800s which correlates to the hottest o2 temp scale there.

 

Cool. I never felt comfortable using the narrowband to tune WOT. I'm definitely taking the wideband with me for every car I own in the future.

 

It's not ideal by no means because there are so many variables to it, but ive done it on several car's over the past 10 years with great success. Before the advent of the wideband, narrowbands were the only thing available for determining the AFR. Ill probably be getting an LM2 over the next few months to share with two buddies of mine and then I can see what the actual o2mv are against the AFR the wideband reads.

 

FWIW I just got 335km to 36L, which is 9.3km/L or 10.75L/km or 21.9MPG.
Only 100km was a nice highway cruising stint, everything else was urban stop and go type stuff.

 

My 06 stock SS/SC with intake and exhaust and full tune up manages between 23-26. As soon as I do any sort of city driving, it takes a **** hard. Really disappointed with that.

 

Since changing my front wheel bearing which got to the point of being quite noisy and really rough when spinning by hand, my mileage has gone up noticeably. I will post up my results at the next fill up, but even with the colder weather, it seems to be around 10L/100km now.