bluebirdvision Posted March 25, 2012 Report Share Posted March 25, 2012 I'm only achieving 16.2 mpg in the city in my Regal. I've heard of people getting a little over 20mpg in these cars. Although I'm 21 I generally drive my car at a snail's pace because I'm terrified about getting a ticket. I had a complete tune up done on the car: Plugs (genuine AC Delco replacements), wires (NAPA Belden) and fuel filter. I have the oil changed every 3,000 miles. What am I doing wrong? Is the fuel mileage lower because of the higher mileage? What can I do to improve it? I was also wondering if the ethanol in the fuel is causing the drop in fuel economy. My Grandma has a 2005 Lesabre, and I've gotten 20mpg in the city with that. Same engine and I believe its got the same transmission. I wish I was able to afford to drive it on the highway more, because it gets anywhere from 27-28.5mpg on the high way, which I think is awesome for a "medium" sized V6. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted March 25, 2012 Report Share Posted March 25, 2012 ethanol will most certainly drop MPGs. 16 in the city is lower than normal, but not by much. EPA ratings are 19/30 for the original test, 17/27 for the "more realistic" adjusted numbers. Quote Link to comment Share on other sites More sharing options...
bluebirdvision Posted March 25, 2012 Author Report Share Posted March 25, 2012 Thanks. I suppose 16mpg is a small price to pay to have GMs premium V6. That ethanol stuff is horrible, I have a little golf cart with a 2stroke engine, and believe it or not, if I don't put the enzyme treatment in the fuel it loses power, runs rough and hot (air cooled) Quote Link to comment Share on other sites More sharing options...
Penglii Posted March 25, 2012 Report Share Posted March 25, 2012 Are you misfiring? I had a fuel injector stuck shut on my '94 3100 and until I fixed it I got 16.4mpg in the city no matter how I drove the car. Quote Link to comment Share on other sites More sharing options...
bluebirdvision Posted March 25, 2012 Author Report Share Posted March 25, 2012 (edited) At idle it has a small misfire , if i put the ethanol treatment in the tank, it stops for a few tanks, and then it comes back. I put it in every third tank. The service engine soon or service vehicle soon telltale lights aren't on... Edited March 25, 2012 by bluebirdvision Quote Link to comment Share on other sites More sharing options...
AL Posted March 25, 2012 Report Share Posted March 25, 2012 I have no torque converter lockup and I saw this doing 75-80 on a 150 mile round trip Quote Link to comment Share on other sites More sharing options...
bluebirdvision Posted March 25, 2012 Author Report Share Posted March 25, 2012 ^ I don't have the DIC, mine is a "stripped" LS. I have to use pen & paper LOL Quote Link to comment Share on other sites More sharing options...
AMP Posted March 25, 2012 Report Share Posted March 25, 2012 I get 15.5 in the GTP I think I need to do some work I think I need a fuel regulator Quote Link to comment Share on other sites More sharing options...
AL Posted March 25, 2012 Report Share Posted March 25, 2012 Your car has a few aerodynamic issues I think Quote Link to comment Share on other sites More sharing options...
AMP Posted March 25, 2012 Report Share Posted March 25, 2012 little bit:lol: Quote Link to comment Share on other sites More sharing options...
gp1991 Posted March 25, 2012 Report Share Posted March 25, 2012 16 is about what i get around town only Quote Link to comment Share on other sites More sharing options...
AMP Posted March 25, 2012 Report Share Posted March 25, 2012 I get 15.5 in the GTP I think I need to do some work I think I need a fuel regulator oh yeah this is in town, I dont drive the Highway much but last time I did I got 30 Quote Link to comment Share on other sites More sharing options...
Schurkey Posted March 25, 2012 Report Share Posted March 25, 2012 (edited) I had a complete tune up done on the car: Plugs (genuine AC Delco replacements), wires (NAPA Belden) and fuel filter. That's not a complete tune-up. It's a good start. Add: Air filter inspection/replacement PCV inspection/replacement Charcoal canister filter inspection/replacement (if used) Cleaning of throttle body including IAC passages Scan-tool verification of no codes and sensor/actuator function Chemical cleaning (gas tank additive such as Techron) of fuel injectors Fuel pressure verification Check tire pressure and condition Check brake drag and condition Check coolant condition/voltage/level Clean battery terminals Verify charging voltage Given a choice, I'd like to see the automotive oscilloscope ignition pattern at idle and under load. This is becoming much more rare, though. Some shops don't even have a 'scope any more. I have the oil changed every 3,000 miles. Almost certainly MUCH TOO OFTEN. While it's not harmful, you're probably spending double or more what you need to for oil changes. 6K might be more appropriate. May go more than that with oil sampling to discover actual oil life. Is the fuel mileage lower because of the higher mileage? Maybe. If piston slap or other "worn-out" engine noises are setting off the knock sensor, the retarded timing will kill power and fuel economy. I was also wondering if the ethanol in the fuel is causing the drop in fuel economy. Yeah. About 3 or 4 percent loss. Edited March 25, 2012 by Schurkey Quote Link to comment Share on other sites More sharing options...
ReBlown47 Posted March 25, 2012 Report Share Posted March 25, 2012 yeah i was gettin around 19-20 last summer then i added a ported tb, ported lim, hv3 insert now i'm gettin around 16-17mpg. Quote Link to comment Share on other sites More sharing options...
bluebirdvision Posted March 25, 2012 Author Report Share Posted March 25, 2012 How would I know if the car had a Charcoal canister? I had the fuel filter changed, the brakes & rotors are new in the front, worn in the rear, I'm going to worry about that around inspection time. I do the LOFs around 3,000 miles, as its an old engine, and I need it to last, its cheap insurance if you ask me. Coolant was flushed and replaced in October 2011, Transmission fluid and filter was just done. Air filter is 8 months old. NAPA replacement. There are no codes, I have those checked every time I have the oil changed. (My Uncle owns the garage where i get it serviced/repaired.) What are you guys running for tire pressure? I'm running 33psi in mine all around. What PCV are you talking about? The PCV Valve??? If I had the money I'd get a cold air intake, but I'm poor. LOL What fuel system cleaner should I use?? Quote Link to comment Share on other sites More sharing options...
Schurkey Posted March 26, 2012 Report Share Posted March 26, 2012 (edited) How would I know if the car had a Charcoal canister? Check service manual or underhood decal for location and whether it has a replaceable filter. I do the LOFs around 3,000 miles, as its an old engine, and I need it to last, its cheap insurance if you ask me. Changing oil more often than you need to is not helping you achieve your goals. The engine is not grateful. If the oil and filter is fit for use...might as well continue to use it. What are you guys running for tire pressure? I'm running 33psi in mine all around. About 35 here. What PCV are you talking about? The PCV Valve??? Yes, along with the rest of the plumbing. If I had the money I'd get a cold air intake Total waste of time, money, effort, and enthusiasm. What fuel system cleaner should I use?? Chemical cleaning (gas tank additive such as Techron) of fuel injectors Edited March 26, 2012 by Schurkey Quote Link to comment Share on other sites More sharing options...
bluebirdvision Posted March 27, 2012 Author Report Share Posted March 27, 2012 I shall purchase some Techron at the time of the next service. Thanks Quote Link to comment Share on other sites More sharing options...
bluebirdvision Posted March 29, 2012 Author Report Share Posted March 29, 2012 I looked up the cost of a PCV valve, and its cheap so I'm going to replace it soon. Quote Link to comment Share on other sites More sharing options...
Andrew Posted March 30, 2012 Report Share Posted March 30, 2012 run some Seafoam. Do a search on it if you are unfamiliar. Quote Link to comment Share on other sites More sharing options...
pitzel Posted March 31, 2012 Report Share Posted March 31, 2012 Oxygen sensors, at least for me, only last 60-80k miles. So if it has never been replaced.. The O2 sensor will be significantly degraded and mileage bad far before the ECM ever complains. Quote Link to comment Share on other sites More sharing options...
bluebirdvision Posted April 4, 2012 Author Report Share Posted April 4, 2012 I had the PCV replaced today, we shall see if the mileage goes up at all. It seems slightly more responsive, if that makes any sense. Quote Link to comment Share on other sites More sharing options...
ChibiBlackSheep Posted April 4, 2012 Report Share Posted April 4, 2012 I was going to suggest Seafoaming (gas tank, crankcase, and through brake booster vacuum) o2 sensor (just the one on the rear manifold) Also, pull the vacuum line off your fuel pressure regulator. Does it smell like gas (or is it wet with gas) that might be going bad also. And you might as well buy a can of MAF cleaner and give it a good spray. Quote Link to comment Share on other sites More sharing options...
bluebirdvision Posted April 5, 2012 Author Report Share Posted April 5, 2012 When I pulled the fuel pressure regulator hose off, the RPMs barely changed at all, it ran SLIGHTLY rough, but not bad, I didn't drive it like that, just sat at idle. Its not wet, looks new, like it may have been replaced. Quote Link to comment Share on other sites More sharing options...
bluebirdvision Posted April 13, 2012 Author Report Share Posted April 13, 2012 20 mpg. SLIGHTLY more highway driving involved. I'd imagine 18-19mpg is more what I'll get normally as I only drive 14 miles to work three days a week Quote Link to comment Share on other sites More sharing options...
skitchin Posted April 13, 2012 Report Share Posted April 13, 2012 That's what I'm getting with my 3100. I average 23MPH and get about 19MPG, constant stop and go traffic to and from work. Seems with 3.33(?) gears and my 3100 that 50-55mph is the butter zone for fuel efficiency. Was coming back into town late the other night and my average was over 40mpg for a short time. I'd say low to mid 30's would be the norm for every day highway driving conditions over flatter land. Quote Link to comment Share on other sites More sharing options...
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