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Discussion Starter · #1 ·
Hey All, Just purchased a 1999 S70 with 6700 miles. (I love it) Im doing mild street driving with a light pedal and the trip computer is coming up with avg of 14 MPG. Amazing enough after a tank of fuel and a calc, I came up with the exact same thing . So this comp. is acurate. Sticker and dealer says Street should be 20 and 29 for highway. had dealer check car and says its allright. sounds strange that im getting close to what a yukon is getting??? Is this to be expected from this Motor? (base 5cyl. no turbo)<br> Thanks for any reply's
 

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Re: 1999 S70 14 MPG , Is that right? (NuYRKS70)

Have you tried to just calculate from the most straightforward manual calculation? Meaning...fill up how many gallons you have and set the trip computer to 0, and see how many miles you can go with that many gallons of fuel. I think these MPG trip computers on these cars are always off by quite a bit. With the amount of modification I have done on my car and the driving style, there's just no way I'm doing close 26 mpg for local and close to 28 for highway. When I use that simple manual calculation...turns out I get roughly around 20~21 mph for city/highway combined, which sounds about right, but still a bit too good too be true.
 

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Re: 1999 S70 14 MPG , Is that right? (The_one_n_only)

Hey One,<br> Yes thats why i posted an inquiry for anyone else that may be getting this kind of mileage. I did it manually with amount of gallons and # of miles and what amazed me was the computer was perfectly accurate. By the way this is NYC street driving, stop and go every 5 seconds. just thought it should get better mileage since several friends with big SUV's get close to this number in the same conditions (5 cyl. non turbo automatic trans)
 

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Re: 1999 S70 14 MPG , Is that right? (NuYRKS70)

Wow..that is bad then. But I would imagine with the mileage you have, you probably don't need any serious tune up just yet. Have you checked your spark plugs, cap, and rotors? Oil change recently? Air filter? Maybe it needs some fuel injection cleaning? <br>That is very weird...
 

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Re: 1999 S70 14 MPG , Is that right? (The_one_n_only)

Doesn't the 99 MY for the 70 series have the individual coil packs over each spark plug? If that is true then it can't be his cap and rotors. Please correct me if I am wrong.<p>Unfortunately I can't help. I don't have a clue what it may be.
 

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Re: 1999 S70 14 MPG , Is that right? (NuYRKS70)

Definately sounds a bit low, even for city driving. Our 99 S70 GLT has seen 18mpg around town when I was driving and it's computer is pretty accurate. My 2000 R's computer is a little off, tells me I'm getting 21 when I'm getting close to 25 on the highway<p>
 

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Re: 1999 S70 14 MPG , Is that right? (83caddy16v)

Maybe the thermostat is stuck open. That would definitely kill your mileage.
 

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Re: 1999 S70 14 MPG , Is that right? (petew)

Hey guys , thanks for all the input.<br> I have done a complete trip computer reset in my initial tests. My average MPH seem to be staying at about 11, with the MPG at about 14. (and again i did back those numbers up with manual calculation) Remember this is a 1999 front wheel drive, base 5 cyl. Should be more effiecient than the 4wd and turbo modelsThe dealer just put this car through its 130 point inspection as a certified used car and did change the oil but i dont think they used mobil1. (which i will be using in a few hundred more miles and it will be 5W30 since winter season is appoaching) I do use Amoco high test and i did check the air filter, it seems to be new. I recieved the car with 28 pnds all the way around and even went to 34 to see if it would change much , but it didnt. Now I am running 32 in front and 28 in the rear as most say is more reasonable. Again the dealer says that the car is running right. I feel no misses and plenty of power. Also very consistent shifting and kickdown. I wonder if it is ignition like you suggest, if a scope or code reader would pick it up. I was also considering a dragging caliper. I will jack it up and check for resistance on each wheel. although brake dust does seem even. I will look at the cap and rotor to see its condition, Those are all good suggestions and I will go after them. Any thing else someone can add ill surely give it a try. I hope to hear from more people that are doing the same kind of driving as me to get some numbers. Im sure that will show this car to either be way off or normal in this kind of driving. THANKS AGAIN ALL
 

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Re: 1999 S70 14 MPG , Is that right? (NuYRKS70)

I had this same exact problem ('cept mine was 15 mpg). It happened for the longest time and I took it to the dealer 3 times. The first time, they cleaned the throttle body. Worked for about 5 hours. The second time they said nothing could be found and sent me home. The third (and final) time they decided that it was due to a dirty air filter. I had a K&N drop-in air filter. I went straight to AutoZone and bought the K&N cleaning kit. I spent about 45-60 minutes cleaning and afterwards, my mileage was up to 25 mile per gallon, highway. That's 10 mpg for the $10 the cleaning kit cost me. Check your filter. See if there is a bunch of blackness all over it. Hope this helps.
 

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Re: 1999 S70 14 MPG , Is that right? (epocs)

wow, how long haven't you cleaned your filter?<p>btw my 96 850 NA is getting consistent 21.5mpg over 3 weeks.
 

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Re: 1999 S70 14 MPG , Is that right? (NuYRKS70)

You're quoting NYC street driving and it sounds like with a lot of stop and go. When you're not going you're getting 0 mpg so it kils your mileage. I used to get less than 20 mpg in my Honda Accord around town. Plus cold engines burn more gas so if you make a lot of short trips that will kill your average too.<p>A closer comparison would be my wife and her 850 n/a. She used to drive around city all the time with only short trips. I remember she had to fill up on 10 gallons with only 180 miles on the trip odo. Then when she started commuting via freeway she was up in the 25-30 mpg range.<p>14 does sound a little low, but given where you're driving it doesn't sound horrible. I would say fill'er up and take a trip on the freeway and see what the mileage is.
 

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My suggestion would be >>>>>

to get some really good fuel injector cleaner like REDLINE or AMSOIL PI put like 1/2 of the bottle in there and put a full tank of the highest grade gas you can find. Go on a 1-2 hour drive on the highway this should clean out your injectors and hopefully increase your mile per gallon. Good luck and God Bless. <IMG NAME="icon" SRC="http://********************/smile/emsmile.gif" BORDER="0">
 
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