Cant get better than 18.1 MPG city/highway

[Quick6'n'-K.C.]

Combined city and highway is only 18.1MPG
The chip has the lean cruise setting

My drive to and from work is 21 highway miles, takes about twenty minutes to get to work in the morning, i usually drive 60-65mph
My drive home, with the AC on usually takes 30-50 minutes, stop and go allllllll thhheeee wayyyy hoommmme
The BLM's are right at 131

The rings are starting to go, i can only get 15inches of vacuum when i let off on the highway. 10-11 inches at idle

Does anyone have any tips to get an average of 20MPG?
Tire pressure is 32, new tires
KN air filter is freshly cleaned
lean cruise in the chip
fuel pressure is 43psi

I have babied this thing for the past month, i have a alky chip in the car, and NO METH KIT... So im never getting into boost, actually driving like a commuter
This sucks, i really thought after never getting after it, i would see about 22mpg..

Guess i could turn down the FP

Anybody else trying to squeeze a lil more out of the tank?

I usually get 280 miles, also have factored the 4% difference in running the 255/60/15 tires.

BW

 

[norbs]

Drive 55's mph and turn the a/c off. Should help alot. i think the thrasher chip gets the best mpg.

 

[buickbert]

drive the cummins :biggrin:
whenever i start caring about mpg i drive my girlfriends 2001 new bettle, tdi, 5 speed quick little sucker and gets around 47mpg :biggrin:

buickbert

 

[Quick6'n'-K.C.]

After working outside in the heat, the best thing is the COLD ac once i get into my car... I cant turn it off, not going to happen!!!

I will try slowing it down to 55-60 and see if anything happens.
Thanks for the reply

BW

 

[Quick6'n'-K.C.]

drive the cummins :biggrin:
whenever i start caring about mpg i drive my girlfriends 2001 new bettle, tdi, 5 speed quick little sucker and gets around 47mpg :biggrin:

buickbert

Trying to save the miles on it for long distance trips, 41K since new may 02...
Gets great fuel mileage, actually better than the buick, but i love driving the buicks!

47 no chit? Thats awesome

BW

 

[jpp]

mpg

:biggrin: sell one of your mannnnnnnnnnnnny cars and use the money for gas!

 

[Quick6'n'-K.C.]

Im trying to get better MPG, not sell a car J.P. LOL

Did you get my email with the naked pics of your girlfriend? :biggrin:

BW

 

[my1stgn]

You sure its the rings that are giving out and not a vacuum leak? Id do a wet/dry compression test and see the different numbers to make sure its the rings..... just my 2 cents.

 

[Quick6'n'-K.C.]

Either headgasket or rings.
I used to run 30-35psi in the motor with low timing

All vacuum leaks are in check, check valves, gaskets ect.
BLMs are 131 and INTs are 129 while driving..

I could do a leakdown test and compression test, i know the answer cause ive beat the crap out of the motor for the past 7 years.

Just trying to get some good gas mileage!!! :biggrin:

BW

 

[bison]

Turning down the FP wont help if you BLM and INT are close to 128 and the ecm is in closed loop. I would slow down to 55mph and see what happens. How long is it taking for the ecm to go into closed loop? You should be able to get more than 18mpg even with the AC on unless you have some bad cylinders. On the next engine you build throw a little more compression at it and you will be suprised how much it helps. Ive hit over 29mpg cruising at 55-60 years ago when i had a lockup converter and 210-205 roller cam in it. Compression ratio was 8.5-1 with a plate honed block and gapless rings. 42.5lb injectors and INT and BLM were at 128-130 while cruising. The fuel economy was always good with that one. I wish i had a lean cruise chip in it. Would have hit over 30mpg. I had one that was 8.7-1 with a smaller cam but never tested it. It was at least as good as the one i previously mentioned. Im not sure how the lean cruise option works but i would think your BLM should go higher unless it locks up at a certain light throttle position and load and or goes into open loop. The open loop scenario seems more probable to me. If it goes into open loop then turning down the FP will certainly help unless you turn it too low for the injectors to operate correctly or get a lean misfire. You could always tell your chip burner what FP you will be running to have to avoid turning it down to get better fuel economy.

 

[SS_Sean]

Another suggestion would be to run the car with more air pressure in the tires. It will make for a bumpier ride, but will help with gas mileage.

 

[ThikStik]

You could try reconnecting the throttle body heat lines. I would think this would , for sure, help in winter, especially with on/off cycles. But I'd hate to do it in warmer months. Kinda crazy to intercool, then reheat mixture. But it does help atomize fuel better which would help mpg.

 

[KevinB]

MAFTPro

I can put my BLMs where ever I want them. You can adjust low, mid and high loads and all at different rpms (400, 800, 1200, 1600, etc.)

 

[jurassic five 7]

Usually when I'm on the highway, i'll go 55 or so, and lock the convertor up with the switch. It goes from 2000ish rpms to about 1500 rpms when I do this.

I don't know what mpg I get because I do city and highway, with some boost combined. Also I have a or some vacuum leaks somewhere.

-Adam

 

[lyonsd]

MAFTPro

I can put my BLMs where ever I want them. You can adjust low, mid and high loads and all at different rpms (400, 800, 1200, 1600, etc.)

That would be great if you can get the damn thing to read the MAF signal.

 

[salvageV6]

18.1 with the A/C on approx. 50% and mixed driving isn't bad at all, try 55mph if you can stand it.

I wouldn't kill yourself over this one your car is running normally.

 

[441120]

Is the TCC locking up? Mine won't lock below 55 so cruising at 45~50 my torque converter is slipping, I have a manual lock-up switch that I use to bring up the MPG up and the trans temp down. If you are in stop and go it's going to be tough to bring the MPG up.

Drive Miss Daisy and crank the A/C and stereo to drown out the horns on all those minivans

 

[VadersV6]

You probably remember my be-all end all thread on mileage called "my mileage sucks". Just about every idea possible was throw out there on that thread. The best Ive ever gotten was 18.6mpg. Big improvement from 8mpg when I first bought it! Took alot of work. The 18.6 was with every vacuum leak in check, every sensor dialed in, ignition working great, perfect tune, tire pressure at 40psi all around, cruising at 65-70, and lean cruise on. I actually saw an increase of 1-2mpg by cutting off the IC scoop. Now I just ignore it (MPG) cuz the obsession was driving me nuts. I drive anywhere from 65 to 80mph and get between 16 to 18mpg, always. I have no TCC lockup. Given I climb through a small mountain range on the way to work, my TCC clutch would probably spend most of its time disengaged anyway, so why bother rushing to fix it.
Make sure your alignment is good. That tire dragging can suck up alot of gas. I know my alignment is gone cause the whole front suspension is wasted and is about to fall out from under the car. Also going to synthetic fluids from end to end can get you an extra 1-2mpg. I remember something VERY strange about my cobra and MPG. Cool thing about those cars is I had 4.56 gears, cruising at 3200 rpm at 80mph with 400 N/A HP, and I got 20mpg like that. I remember my MPG would drop ALOT, and it was connected to my PCV valve for some reason. The valve would make a buzzing sound from the plate cycling when it was working right. It would varnish up, stick a little and stop buzzing, and my MPG would drop to 15. Very weird.
Ive often wondered if having the wastegate adjusted a certain way during cruise can have a significant affect on MPG.

 

[bison]

You probably remember my be-all end all thread on mileage called "my mileage sucks". Just about every idea possible was throw out there on that thread. The best Ive ever gotten was 18.6mpg. Big improvement from 8mpg when I first bought it! Took alot of work. The 18.6 was with every vacuum leak in check, every sensor dialed in, ignition working great, perfect tune, tire pressure at 40psi all around, cruising at 65-70, and lean cruise on. I actually saw an increase of 1-2mpg by cutting off the IC scoop. Now I just ignore it (MPG) cuz the obsession was driving me nuts. I drive anywhere from 65 to 80mph and get between 16 to 18mpg, always. I have no TCC lockup. Given I climb through a small mountain range on the way to work, my TCC clutch would probably spend most of its time disengaged anyway, so why bother rushing to fix it.
Make sure your alignment is good. That tire dragging can suck up alot of gas. I know my alignment is gone cause the whole front suspension is wasted and is about to fall out from under the car. Also going to synthetic fluids from end to end can get you an extra 1-2mpg. I remember something VERY strange about my cobra and MPG. Cool thing about those cars is I had 4.56 gears, cruising at 3200 rpm at 80mph with 400 N/A HP, and I got 20mpg like that. I remember my MPG would drop ALOT, and it was connected to my PCV valve for some reason. The valve would make a buzzing sound from the plate cycling when it was working right. It would varnish up, stick a little and stop buzzing, and my MPG would drop to 15. Very weird.
Ive often wondered if having the wastegate adjusted a certain way during cruise can have a significant affect on MPG.

I hope you have temp guage and a big external trans cooler in addition to the one in the radiator if your cruising with the TCC unlocked for extended periods. I would manually lock it and drive in 3rd to avoid overheating the trans. As for the cobra, the PCV actually creates a vacuum leak and leans out the part throrttle mixture some. When its pluged in that instance the ecm probably cant correct for that much difference in air flow so it runs rich at light loads sucking up the gas. Im sure it could be reflashed to run without a PCV and not waste fuel.

 

[VadersV6]

I hope you have temp guage and a big external trans cooler in addition to the one in the radiator if your cruising with the TCC unlocked for extended periods. I would manually lock it and drive in 3rd to avoid overheating the trans. As for the cobra, the PCV actually creates a vacuum leak and leans out the part throrttle mixture some. When its pluged in that instance the ecm probably cant correct for that much difference in air flow so it runs rich at light loads sucking up the gas. Im sure it could be reflashed to run without a PCV and not waste fuel.

Well the fuel trims were never maxed out, so that theory probably wasnt the case, unless the O2's werent reading right, which I doubt.
Ive put about 15,000 miles on this D5 converter with the lockup not working. The slip is only about 200rpm, while the Art Carr 3800 stall N/L i had in there before for 17,000 miles (these numbers are all highway, climbing mountains every day) was slipping alot more and I never had an issue really. I did throw in an external cooler about 3 months ago. Get this. The fluid was sitting in that trans for the 4 years it sat before I bought it. Who knows how long it was in there before that. Ive since put 32000 miles on that fluid. It still looks and smells good and have no issues. I definetely have to change it, but Im waiting until I have cash to get my TCS 9-11 converter cut open to get some shattered fiber ring fixed (I got screwed on a trade), and then Im going to replace the pressure switches, new filter and fluid and lockup solenoid all at once. Pulling the tranny is such a PITA though. I was pretty miserable when doing the D5 swap.