Poor fuel mileage
Senior Member
Joined: 06-25-07
Posts: 6,003
Likes: 0
From: Kissimmee, Fl
If your ltft is that high, then your short terms are most likely hitting double digits quite often since that number is just an average over time.
Again, I'd be surprised if there's no code.
Again, I'd be surprised if there's no code.
Yeah 23mpg is not right bro. Unless you're idling that car like mad in drive-thru's and traffic.
What type of tires you running and are they in good condition and at proper PSI?
Spark plugs? You're approaching gm recommended 160,000km change. (I've change mine every 75,000km cheap investment)
Last Oil change? Fresh oil can make a noticeable difference.
Driven with that zzp tune in winter before? Could just be geared towards making more power.
When have you last reset your fuel estimate? I always reset it every few tanks. And ignore results until you've put on 200km+.
What type of tires you running and are they in good condition and at proper PSI?
Spark plugs? You're approaching gm recommended 160,000km change. (I've change mine every 75,000km cheap investment)
Last Oil change? Fresh oil can make a noticeable difference.
Driven with that zzp tune in winter before? Could just be geared towards making more power.
When have you last reset your fuel estimate? I always reset it every few tanks. And ignore results until you've put on 200km+.
You might want to get those fuel trims adjusted.
I'm astounded at people riding around with fuel trims that out of whack. And I'm shocked you're not throwing a "too rich at idle" code... Assuming you don't have a CEL or if you do don't even bother to check it.
By the way, I wouldn't rely on your interceptor gauge alone for that. If you are tuned you need to be logging the car and going back to review your logs. You will be absolutely amazed at the nonsense you miss just by trusting an interceptor. Because let's face it, when you are WOT or in heavy traffic, you're not putting your eyes on that gauge long enough to retain any valuable amount of information. There's going to be a ton of peaks and valleys where your trims probably spike into the double digits or just plain zero out on you under certain driving conditions.
The cheap tuners way to fix things like this is "let's just command more fuel here and take fuel out there in this table".
Come on kids!
I'm astounded at people riding around with fuel trims that out of whack. And I'm shocked you're not throwing a "too rich at idle" code... Assuming you don't have a CEL or if you do don't even bother to check it.
By the way, I wouldn't rely on your interceptor gauge alone for that. If you are tuned you need to be logging the car and going back to review your logs. You will be absolutely amazed at the nonsense you miss just by trusting an interceptor. Because let's face it, when you are WOT or in heavy traffic, you're not putting your eyes on that gauge long enough to retain any valuable amount of information. There's going to be a ton of peaks and valleys where your trims probably spike into the double digits or just plain zero out on you under certain driving conditions.
The cheap tuners way to fix things like this is "let's just command more fuel here and take fuel out there in this table".
Come on kids!
Last edited by Speed_Thrills; Dec 22, 2014 at 02:45 PM. Reason: Automerged Doublepost
Ltft in the 7-9 range? U need to get off that trifecta tune lol should be around 0
Look at your intake valves. I'm betting your valves are pretty coked. Pull the brake booster nipple and use a bore scope to look at #3
Also where in MI are you?
Also where in MI are you?
Last edited by ECaulk; Dec 22, 2014 at 10:57 PM. Reason: Automerged Doublepost
How many tanks of gas are we talking? One bad tank possibly? Secondly I believe winter gas if for all of the US not just part of it, which plays another big factor.
Forgot about the valves, check that first, a very common issue that's not all that hard to fix.
Forgot about the valves, check that first, a very common issue that's not all that hard to fix.
I didn't think of that.. Though I'm not sure it would cause such an abrupt change. I'm getting ready to do 80k maintenance so I'll be sure to make that part of it.
I'm talking 2 months worth of tanks, probably 9-10ish. I'm leaning toward O2, like I said, but I'm sure winter gas isn't helping.. I know my car and how it acts in the winter (3 previous winters anyway) and this is uncharacteristic.
Def should check that out. I'm in hillsdale for the time being, if you where close and didnt know where I was talking I could of meet up and showed you
Yeah should be around 19inHg vac at idle. If the AC is on then it'll come up to 17 or so. FYI, your idle vac numbers shouldn't be directly affected by anything upstream of the throttle body (eg boost leak), if that helps your diagnosis. Things upstream could indirectly affect it tho.
Yeah should be around 19inHg vac at idle. If the AC is on then it'll come up to 17 or so. FYI, your idle vac numbers shouldn't be directly affected by anything upstream of the throttle body (eg boost leak), if that helps your diagnosis. Things upstream could indirectly affect it tho.
Senior Member
Joined: 06-03-07
Posts: 14,142
Likes: 71
From: NY
Please tell me you're not resetting the DIC at 72 mph and going "omg, my gas mileage is so bad!"
Do it the right way and fill your tank to full. Record odometer at this time. Drive and then fill to full again. Note odometer again. Divide miles driven by gallons filled. There's your mileage.
Only way to do it. My LSJ gets 30 on the "highway", exactly what the window sticker says. Driving on county roads gets between 22 and 25, again what the window sticker says. The dash computer can be off by 2-3 mpg, sometimes more.
Do it the right way and fill your tank to full. Record odometer at this time. Drive and then fill to full again. Note odometer again. Divide miles driven by gallons filled. There's your mileage.
Only way to do it. My LSJ gets 30 on the "highway", exactly what the window sticker says. Driving on county roads gets between 22 and 25, again what the window sticker says. The dash computer can be off by 2-3 mpg, sometimes more.
Please tell me you're not resetting the DIC at 72 mph and going "omg, my gas mileage is so bad!"
Do it the right way and fill your tank to full. Record odometer at this time. Drive and then fill to full again. Note odometer again. Divide miles driven by gallons filled. There's your mileage.
Only way to do it. My LSJ gets 30 on the "highway", exactly what the window sticker says. Driving on county roads gets between 22 and 25, again what the window sticker says. The dash computer can be off by 2-3 mpg, sometimes more.
Do it the right way and fill your tank to full. Record odometer at this time. Drive and then fill to full again. Note odometer again. Divide miles driven by gallons filled. There's your mileage.
Only way to do it. My LSJ gets 30 on the "highway", exactly what the window sticker says. Driving on county roads gets between 22 and 25, again what the window sticker says. The dash computer can be off by 2-3 mpg, sometimes more.