19Cutlass94 Posted September 3, 2008 Report Share Posted September 3, 2008 Recently I drove like 390 all highway miles, and i only got 25mpg... on straight highway! I mean maybe it was because it was going like 70-75 some of the time, but that cant be the whole reason as to why. Is it possible I might have an injector thats stuck open or leaking? Would i be able to test this by ohm testing the injectros or no? Quote Link to comment Share on other sites More sharing options...
IRONDOG442 Posted September 3, 2008 Report Share Posted September 3, 2008 you ought to see why my Intyrigue is getting and you would stop bitching about it ~ Quote Link to comment Share on other sites More sharing options...
Crazy K Posted September 3, 2008 Report Share Posted September 3, 2008 you ought to see why my Intyrigue is getting and you would stop bitching about it ~ But you don't count. You only operate the car at 100% open throttle and over 100mph as much as possible. Quote Link to comment Share on other sites More sharing options...
Captain Ficho Posted September 3, 2008 Report Share Posted September 3, 2008 Change your fuel filter lately? Quote Link to comment Share on other sites More sharing options...
Addicted to eaton Posted September 3, 2008 Report Share Posted September 3, 2008 you ought to see why my Intyrigue is getting and you would stop bitching about it ~ But you don't count. You only operate the car at 100% open throttle and over 100mph as much as possible. i get 26 avg in my l67 Quote Link to comment Share on other sites More sharing options...
Captain Ficho Posted September 3, 2008 Report Share Posted September 3, 2008 on average, all highway I get 25 in my LQ1 Quote Link to comment Share on other sites More sharing options...
BIGBULS Posted September 3, 2008 Report Share Posted September 3, 2008 Check the basics: Â Tire pressures. Air filter. PLugs (state of tune). DRIVING HABITS (even a good run of fuel econ can be badly skewed by one top speed pull.........don't ask how I know ). Â Oh.........and here's one...........was it windy?? Â Even a crosswind can fuck up fuel econ very nicely. Â Â Â And finally...........even E10 ethanol gas can hurt 3-4% as compared to regular 87 octane. Quote Link to comment Share on other sites More sharing options...
Breakdown Posted September 3, 2008 Report Share Posted September 3, 2008 Recently I drove like 390 all highway miles, and i only got 25mpg... on straight highway! I mean maybe it was because it was going like 70-75 some of the time, but that cant be the whole reason as to why. Is it possible I might have an injector thats stuck open or leaking? Would i be able to test this by ohm testing the injectros or no? Â That really sounds par for the course to me. Did you used to get lots better? Â My picks - if you did. Â Catalytic converter or EGR. Â Most likely cat, when was the last time that was replaced (if it was?) Quote Link to comment Share on other sites More sharing options...
Addicted to eaton Posted September 3, 2008 Report Share Posted September 3, 2008 my car 97 gtp 3800 supercharged V6  Highway 75mph 30mpg 65mph 34.5-35.5 mpg 55 45-55 mpg  In town 20-23mpg  my avg 26.3 Quote Link to comment Share on other sites More sharing options...
Brian P Posted September 3, 2008 Report Share Posted September 3, 2008 my car 97 gtp 3800 supercharged V6  Highway 75mph 30mpg 65mph 34.5-35.5 mpg 55 45-55 mpg  In town 20-23mpg  my avg 26.3  What's that, based off your trip computer?   Jay, 25 MPG for 70-75 is a little but under what it should get, but remember you're still un-tuned. Even though your PCM fuel trims show it's "alright" there's more to be had by getting it tuned. With my stock L82 PCM I couldn't pull greater than 22 MPG on my commute, but after tuning I range from 24-26 consistently and that was after simple fuel adjustment and timing advancement. Also remember the 3.33 FDR will stop you from hitting much higher at those speeds. The W-bodies with the factory 3400's usually had 2.84's and that's one of the ways they were rated so high on the highway. When I drop my speed to the ~65 mph range, I realistically see around 28 MPG.     Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted September 3, 2008 Author Report Share Posted September 3, 2008 my car 97 gtp 3800 supercharged V6  Highway 75mph 30mpg 65mph 34.5-35.5 mpg 55 45-55 mpg  In town 20-23mpg  my avg 26.3  What's that' date=' based off your trip computer?   Jay, 25 MPG for 70-75 is a little but under what it should get, but remember you're still un-tuned. Even though your PCM fuel trims show it's "alright" there's more to be had by getting it tuned. With my stock L82 PCM I couldn't pull greater than 22 MPG on my commute, but after tuning I range from 24-26 consistently and that was after simple fuel adjustment and timing advancement. Also remember the 3.33 FDR will stop you from hitting much higher at those speeds. The W-bodies with the factory 3400's usually had 2.84's and that's one of the ways they were rated so high on the highway. When I drop my speed to the ~65 mph range, I realistically see around 28 MPG. [/quote']  yeah I guess that makes more sense to me now that I think about it like that. I just thought that I should be getting more than that. Im gonna try to slow down to ~65-66 on the highway and not punch it to get around slower cars on the backroads. I wanna try and get it close to ~28 or so, then Id be happy. But when I hooked up the AFR, it read the correct fuel trims, ok well more correctly speaking the correct AFR, for what it should be. Even though its untuned. WOT it dips down to 12.5AFR. It just seems like the 93 in my car goes a little bit faster than it should be. Quote Link to comment Share on other sites More sharing options...
Brian P Posted September 4, 2008 Report Share Posted September 4, 2008 you're a richer guy than me I stick with strictly 87 octane laced with ethanol. I have enough fun filling the F-body tank with premium. Â Do you get any knock retard running 87? Quote Link to comment Share on other sites More sharing options...
AWeb80 Posted September 4, 2008 Report Share Posted September 4, 2008 A Post So I Can Follow This Thread Quote Link to comment Share on other sites More sharing options...
BXX Posted September 4, 2008 Report Share Posted September 4, 2008 you're a richer guy than me I stick with strictly 87 octane laced with ethanol. I have enough fun filling the F-body tank with premium. Â Do you get any knock retard running 87? Â After seeing your timing maps, how the hell do you get away with using 87 and seeing no KR??? Hell, I see KR with 89 Quote Link to comment Share on other sites More sharing options...
Brian P Posted September 4, 2008 Report Share Posted September 4, 2008 because of my cam. There is a lot of valve overlap and duration which causes #1 natural exhaust gas recirc; #2 lower dynamic compression. Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted September 4, 2008 Author Report Share Posted September 4, 2008 Im almost positive i have KR on 87. I just dont know how much. using 87, the car has no balls at all. 89 was better, but it seems to run the best on 93. Quote Link to comment Share on other sites More sharing options...
Fleeingpepper Posted September 4, 2008 Report Share Posted September 4, 2008 I almost got to 20 mpg once when it was 70-80% highway. Yeah! I'm jealous! Quote Link to comment Share on other sites More sharing options...
92GPSpeeder Posted September 4, 2008 Report Share Posted September 4, 2008 My '92 averaged 20.5 on 93 so be happy with 25. Â As Obama said, check your tire pressure! Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted September 4, 2008 Author Report Share Posted September 4, 2008 tire pressure is right around 36psi every tire. Quote Link to comment Share on other sites More sharing options...
Brian P Posted September 5, 2008 Report Share Posted September 5, 2008 then get tuneups Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted September 5, 2008 Author Report Share Posted September 5, 2008 tuneups?! Quote Link to comment Share on other sites More sharing options...
AWeb80 Posted September 5, 2008 Report Share Posted September 5, 2008 ya, inflate your tires Quote Link to comment Share on other sites More sharing options...
kwk39018 Posted September 6, 2008 Report Share Posted September 6, 2008 I'm only getting 25mpg with 40 psi in my tires.It seems to be common the 1st gens get poor gas mileage. Quote Link to comment Share on other sites More sharing options...
Lumineer Posted September 7, 2008 Report Share Posted September 7, 2008 I just skimmed through this thread and skoffed because MY Lumina gets shittier mileage, I think. I estimated probably lower than 20 to the gallon. But, then again, I've done so much high-speed driving and rev limiting that I probably haven't helped the engine much.........and I accelerate HARD. Quote Link to comment Share on other sites More sharing options...
AL Posted September 7, 2008 Report Share Posted September 7, 2008 it wouldnt hurt to check your plugs/wires... if they get bad, they can hurt mileage Quote Link to comment Share on other sites More sharing options...
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