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Post by marksommer on Dec 31, 2013 14:54:02 GMT -6
Hi everyone, in the past 6 months I have changed my plugs and wires. AC Delco 41-950 with four Carquest Gold wires on the rear and four Duralast wires in the front. This was due to replacing the rear wires two years ago due to squirrel eating them; and I could find no other wires day of tune up. Also I have removed the baffle on the air hose, plugged it with a test plug and cut the white plastic out of the air box and replaced air filter. Throttle position sensor was changed. Idle Air Control valve was extensively cleaned and lightly oiled with a few drops of household oil. Ran a couple bottles of redline SL-1 over the course of the last couple oil changes. Also changed fuel filter a couple times and sealed leak in top of gas tank, also cleaned fuel pump and replaced sock. All four brakes are new and tires are balanced. My MPG is now around 18.6 on the highway, using cruise control when I'm not aggressively passing. A couple years ago I used to get 21 or more on my 65 mile drive to work. I ran some seafoam thru the oil last time, it seemed to have no effect. The car seems to be running quite well. My oil is Valvoline Maxlife nextgen 5w30 with Mobil 1 EP filter, so maybe I should try to obey the speed limit for a week and see how it goes. Btw, my tires are set at 35 psi when slightly warm (driven about 4 miles to the station with free air). Any suggestions?
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Post by oldsAURORAmobile on Dec 31, 2013 20:35:43 GMT -6
The MAF sensor should not have any oil or residue on the wire. Also a TPS sensor re-learn may be in order:  |
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Post by lanceslambos on Jan 1, 2014 20:37:09 GMT -6
I'd say your tires are 9 pounds low to start with (44), your using thicker oil than you should be (10W30) and are you using premium fuel? Also, you will always get worse fuel mileage when using fuel injector cleaners. Pull a plug and see how the tip looks. You could be running lean. If applicable use your cruise control more often. The air box mod won't change your fuel mileage.
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Post by sall on Jan 1, 2014 20:54:37 GMT -6
What is your RPM at 70mph? Check fuel trims and fuel pressure at rail. Check plugs to see if they look lean as mentioned by Lance. your using thicker oil than you should be (10W30) No. 5w-30 is perfectly fine for this time of year. 5w-30 is the same weight at operating temp but 'thinner' when cold(easier cold start starts). A 5w-30 would be a-okay all year. I am running 5w-40(Rotella T6). |
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Post by marksommer on Jan 1, 2014 23:52:11 GMT -6
Thank you. I made a mistake in the original post saying that I had oiled the MAF sensor. It was the idle air control valve that I cleaned and then put a few drops of oil on the part that moves/spring. I did that TPS sensor relearn the night I put it in. 5W30 is called for in this weather and I have no intention of inflating my tires to 44 psi during the winter. I ran 40 psi over the summer. The ride was harsh and the mileage didn't go up at all. Also, it has been over a month since I ran any type of fuel system cleaner. By the way the MAF sensor and throttle body have both been cleaned. I do it twice a year.
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Post by marksommer on Jan 2, 2014 0:03:16 GMT -6
The RPM at 70 MPH is just above 2,000 same as it has always been. I have changed my trans fluid twice to Valvoline Maxlife dex/merc. Also I pumped it out with the hand pump about 4 different times in addition to draining and refilling the proper way twice. It has a new AC Delco filter and gasket. In total I replaced about 18 quarts of fluid doing all this. The level is about halfway up the hot crosshatch marks after properly warmed up.
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Post by sall on Jan 2, 2014 7:52:57 GMT -6
Just a FYI. 4t80e is dry sump. No fluid present if car not on when looking down fill hole. Checking the fluid needs to be done at operating temp, on a level surface, cycle all the way through gears and then check the level.
Grab a scanner and check fuel trims, check fuel pressure at rail with gauge, check plugs and check for vac leaks. Report back!
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RCA1186
Administrator 
Rob
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Post by RCA1186 on Jan 2, 2014 12:53:18 GMT -6
I'd say your tires are 9 pounds low to start with (44), your using thicker oil than you should be (10W30) and are you using premium fuel? Also, you will always get worse fuel mileage when using fuel injector cleaners. Pull a plug and see how the tip looks. You could be running lean. If applicable use your cruise control more often. The air box mod won't change your fuel mileage. Go off of the sticker on the driver door not the Max Pressure on the tire. Classic is recommended 30PSI. |
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Post by lanceslambos on Jan 2, 2014 18:14:48 GMT -6
rca99aurora is right, I just haven't seen a car tire in years and years that wasn't a 44 psi tire. I remember my Mustangs from highschool having 33( or 30 something) psi tires though. I just assumed they didn't make them anymore!
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Post by ntrenn on Jan 2, 2014 19:57:46 GMT -6
Low fuel economy:
1. Winter gas (2-3 mpg)
2. Cold weather with short trips
3. O2 sensors reading lean (had a Silverado shooting fire out the exhaust pipes due to this)
4. Dribbling fuel injectors
Get the car on a good scanner and watch the 02 sensor switching and the fuel trims. They will lead you to the answer you seek.
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Post by lanceslambos on Jan 3, 2014 9:32:00 GMT -6
oh ya...duh. ntren is right. how could I forget, winter gas and cold weather are likely the major culprit!
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