Imp558 Posted October 1, 2009 Report Share Posted October 1, 2009 So I'm only getting 15 MPG city, 89 octane gas, and it's been that way for as long as I've owned it. My 1984 Dodge longbed 318 gets 16 city with the original engine so I'm not really thrilled about this. Today I decided to flush the cooling system before winter and did an ECT at the same time. My new ECT and old ECT both read correctly on my Ohm meter, and my IAT is alright too. This spring my fans weren't coming on and I bypassed the relays so I was sure the ECT was the winner. As far as I know it's not holding onto any codes and the MIL is off. Any thoughts? Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted October 1, 2009 Report Share Posted October 1, 2009 city driving is effected a LOT just by driving style... take a look at the MAF and O2 Sensors... they don't have to throw codes to give you shitty economy... Quote Link to comment Share on other sites More sharing options...
xtremerevolution Posted October 1, 2009 Report Share Posted October 1, 2009 The weight difference isn't that great between that and my Regal, and city/highway with constant spirited driving, I average about 20.5mpg. I can get 21-22 if I'm easy on the throttle for that tank of gas, but its not very common. Highway I average 28mpg at 75mph. Go through the standard items. Spark plugs/wires Air filter O2 sensor SES codes MAF sensor (needs cleaning?) Dragging rear brakes/park brake cable (not sure if this is an issue with the Montes) Ever done seafoamed the car? That alone boosted a guy 4MPG here in a similar fuel economy thread a week or so ago. Just scroll down some in this section and you'll find it. Quote Link to comment Share on other sites More sharing options...
Imp558 Posted October 1, 2009 Author Report Share Posted October 1, 2009 20 is my target. I just ran my scan tool on it again and it's all clear. I'll do some research today on testing the MAF and O2 sensors and see what I can come up with. Thanks guys. Quote Link to comment Share on other sites More sharing options...
xtremerevolution Posted October 1, 2009 Report Share Posted October 1, 2009 20 is my target. I just ran my scan tool on it again and it's all clear. I'll do some research today on testing the MAF and O2 sensors and see what I can come up with. Thanks guys. Just remove the MAF and clean it very carefully with q-tips and alcohol. I've done it several times and always had good results. Quote Link to comment Share on other sites More sharing options...
Imp558 Posted October 1, 2009 Author Report Share Posted October 1, 2009 alright, I'm gonna do it now and then it'll take a couple days for me to burn enough gas to figure my economy. I know that a rear O2 makes 0.9V every 3.3 seconds. (I have a good circuit that makes that signal for "testing" of course) Does anybody know what a good MAF and front O2 would look like on my scope? Quote Link to comment Share on other sites More sharing options...
94 olds vert Posted October 1, 2009 Report Share Posted October 1, 2009 My parents GTP 15 mpg in the city. Quote Link to comment Share on other sites More sharing options...
birdman Posted October 1, 2009 Report Share Posted October 1, 2009 i think my regal gets 22-23avg and about 30hwy. Quote Link to comment Share on other sites More sharing options...
Imp558 Posted October 1, 2009 Author Report Share Posted October 1, 2009 Done, I'll have to figure my mileage now. Hopefully I won't have to drive the truck for economy, lol. Still looking for expected signal data on the O2's and MAF. MAP is new and I may block off the EGR and tune it out of the PCM. Quote Link to comment Share on other sites More sharing options...
mfewtrail Posted October 2, 2009 Report Share Posted October 2, 2009 You should be running 87 octane in that car if that 3800 isn't supercharged.. That's all it requires and you'll probably see a slight mileage improvement from using it. Running 89 is just taking money out of your pocket for no good reason. Quote Link to comment Share on other sites More sharing options...
Night Fury Posted October 2, 2009 Report Share Posted October 2, 2009 You should be running 87 octane in that car if that 3800 isn't supercharged.. That's all it requires and you'll probably see a slight mileage improvement from using it. Running 89 is just taking money out of your pocket for no good reason. Wanna know something wasteful? I accidentally put $30 worth of mid grade in the u-haul this morning. Wasted like $13 fuckin dollars!!! Quote Link to comment Share on other sites More sharing options...
Andrew Posted October 2, 2009 Report Share Posted October 2, 2009 So I'm only getting 15 MPG city, i would like a more detailed explanation of your city driving. is it 'drive 1 mile to work/school, 25mph stop and go'? or is it '30mph consistent a couple miles'? the two will have quite different avg MPG's. Quote Link to comment Share on other sites More sharing options...
Night Fury Posted October 2, 2009 Report Share Posted October 2, 2009 So I'm only getting 15 MPG city, i would like a more detailed explanation of your city driving. is it 'drive 1 mile to work/school, 25mph stop and go'? or is it '30mph consistent a couple miles'? the two will have quite different avg MPG's. ^Speaks the truf Quote Link to comment Share on other sites More sharing options...
Imp558 Posted October 2, 2009 Author Report Share Posted October 2, 2009 So I'm only getting 15 MPG city, i would like a more detailed explanation of your city driving. is it 'drive 1 mile to work/school, 25mph stop and go'? or is it '30mph consistent a couple miles'? the two will have quite different avg MPG's. It's 1 - 5 mile trips. most of it is 35 mph stop and go. Occasionally I get 10 miles of highway driving. Has anybody figured 3800 actual mpg with different octanes yet? That could make a neat study. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted October 2, 2009 Report Share Posted October 2, 2009 you should NOT have mentioned that... now the whole octane wars are gonna start again, so i'm going to try to ninja this response in: on the same tune, if a car runs fine(as in no knock detected) on a certain grade of gas, going higher will net you nothing at all. going lower(if no knock gets picked up) can keep the same economy. once you start picking up knock, your economy WILL drop. so: use the cheapest gas you can without picking up knock. don't use your ears either, the knock sensor is MUCH more sensitive.... and beware: some stations have 87, then 89 which is 87 with a little ethanol added to bring the octane to 89. you WILL lose economy with ethanol blended fuels. Quote Link to comment Share on other sites More sharing options...
xtremerevolution Posted October 2, 2009 Report Share Posted October 2, 2009 that would also depend on things like your engine's age and wear, your location's altitude, humidity on a given day, temperature, tire sidewall stiffness, Quote Link to comment Share on other sites More sharing options...
Imp558 Posted October 2, 2009 Author Report Share Posted October 2, 2009 True. I'm in Erie, so we're at great lakes altitude like many of the guys here. My driving is a little aggressive mainly it depends on what's going on around me with other drivers. My tires are descent quality, but they're about done, and I have my own compressor so they're always aired up. It's never really hot and sunny here, for the most part. I think the car's got about 120K on it but it's pretty strong. And one of my wheel bearings is a little grumpy but I haven't had a chance to replace it. My mileage was poor before it started grumbling too. I still think it should be better than 15. Quote Link to comment Share on other sites More sharing options...
AL Posted October 2, 2009 Report Share Posted October 2, 2009 I averaged 26 last tank, but I do 90% 55 mph highway driving, thats also with many WOT runs from stoplights and a couple 0-107 runs... I have 96000 on my car Quote Link to comment Share on other sites More sharing options...
MonteCarloChick Posted October 2, 2009 Report Share Posted October 2, 2009 Try using Mobil gasoline with no ethanol if at all possible Quote Link to comment Share on other sites More sharing options...
xtremerevolution Posted October 2, 2009 Report Share Posted October 2, 2009 Mobile here SUCKS. I don't know about you, but even using their premium here, I can feel the bonneville's northstar idling rough with their gas. it runs like shit in my regal too. The two (and only ones available in the us) cleanest and best fuel companies (rated at some site, I forget which) are Shell and Phillips. Phillips makes 76, route 66, and conoco iirc. Quote Link to comment Share on other sites More sharing options...
mfewtrail Posted October 2, 2009 Report Share Posted October 2, 2009 The two (and only ones available in the us) cleanest and best fuel companies (rated at some site, I forget which) are Shell and Phillips. Phillips makes 76, route 66, and conoco iirc. This is probably what you're referencing: http://www.toptiergas.com/retailers.html Quote Link to comment Share on other sites More sharing options...
MonteCarloChick Posted October 2, 2009 Report Share Posted October 2, 2009 Mobile here SUCKS. I don't know about you, but even using their premium here, I can feel the bonneville's northstar idling rough with their gas. it runs like shit in my regal too. The two (and only ones available in the us) cleanest and best fuel companies (rated at some site, I forget which) are Shell and Phillips. Phillips makes 76, route 66, and conoco iirc. I switched from other gas to Mobil and noticed an improvement in fuel economy plus a little more get up and go in my 3100. We only have Mobil, Noco and Sunoco here.. plus smaller chains Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted October 2, 2009 Report Share Posted October 2, 2009 interesting page: http://www.fuel-testers.com/state_guide_ethanol_laws.html unfortunately all three states i'm within 5 miles from DO NOT require labeling on the pump when it contains ethanol... Quote Link to comment Share on other sites More sharing options...
xtremerevolution Posted October 2, 2009 Report Share Posted October 2, 2009 Mobile here SUCKS. I don't know about you, but even using their premium here, I can feel the bonneville's northstar idling rough with their gas. it runs like shit in my regal too. The two (and only ones available in the us) cleanest and best fuel companies (rated at some site, I forget which) are Shell and Phillips. Phillips makes 76, route 66, and conoco iirc. I switched from other gas to Mobil and noticed an improvement in fuel economy plus a little more get up and go in my 3100. We only have Mobil, Noco and Sunoco here.. plus smaller chains I guess if that's your only other option over Noco and Sunoco, then that's the best choice. I just assumed you had a Shell or Phillips station nearby. The two (and only ones available in the us) cleanest and best fuel companies (rated at some site, I forget which) are Shell and Phillips. Phillips makes 76, route 66, and conoco iirc. This is probably what you're referencing: http://www.toptiergas.com/retailers.html That's the one. They've updated it since I last checked it. Quote Link to comment Share on other sites More sharing options...
PROTESTtheHERO Posted October 4, 2009 Report Share Posted October 4, 2009 when i run 87 i get shit milage (20mpg) but when i run Shell's new V-power 91 octane i get at least 40% better milage (up to the 30s). believe me if u will, but it works and i know it. it also gives a bit more bite to my series 1 when i put 'er to the rug. i know that im never guna run regular again, its more of a waste in the long run with the 5 cents per litre i save and the 40% fuel consumption i lose, theres a clear winner. V-power FTW! Quote Link to comment Share on other sites More sharing options...
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