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Thread: Bad gas milage in new to me mirage

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    Bad gas milage in new to me mirage

    Okay so me and my wife have four mirages, and we deliver pizza in them. 2020 ES 39mpg city and 46mpg hwy, 2020 LE 37mpg city 44mpg hwy, 2014 DE manual 41mpg city 48mpg hwy, and we just bought a 2015 ES with 105,000 miles and it is getting 28mpg city and 46mpg hwy, I compared the fuel trim and o2 sensor voltage to the other three cars and it is very similar. fuel trim long and short is within 4.0% and voltage on o2 sensors is within specification according to FSM. I changed the plugs and the belt, have done italian tune up and made sure tires and brakes were not the problem. Alternator tested fine. I tried turning the blower fan up to 5 bars instead of 1 and it got 35mpg city, so thought it may be a/c, tried on 5 bars again last night and back down to 28mpg. It has me stumped, unlike the 2020 mirages i can not read the fuel pounds per minute on the 2014 and 2015 so I don't know how much is uses at idle. my 2020ES is .01lbs/min @ 750rpm and the 2020LE is .02lbs/min at 750rpm, not sure why they are different but the LE does get worse mileage than the ES.

    So main question is, what can I check next on this 2015 ES to determine why its only 28mpg

    my secondary question is why are my 2020 mirages using different amounts of fuel?



  2. #2
    1. Are you basing these stats on hand calculated figure or just reading the cluster?
    2. Are you and your wife the only 2 people to drive your 4 cars?
    3. Why do you have 4 cars?
    4. A total shot in the dark here....if there are zero obvious variables(ie:driver,weather,tires(size-tread-weight etc..),brake dragging,then maybe try checking the charging voltage? There is a wire that runs from the alternator along the harness above the intake that is relatively common to break and make the alternator put out a constant 14-15volts and likely bogging down the engine a little more than usual. Sometimes the batt/alt warning light will turn on and sometimes the only way I know is via gps tracker that I once in a while take a look at to make sure nobody is driving obvliously with a bad alternator/idiot light on.
    5. I assume you've already checked or replaced the air filter at this point?
    6. is your new to you car a 5spd too? or did I miss that part? If so maybe replace the fluid? Wouldn't hurt if it hasn't been done and who know's maybe it's full of something thats too thick?
    Mirage videos:

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 37.7 mpg (US) ... 16.0 km/L ... 6.2 L/100 km ... 45.3 mpg (Imp)


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    First - All my responses are constructive, no criticism here. I just don't convey my thinking clearly so sometimes it sounds like criticism, but it is not.

    Second - How much data do you have to support the 28 mpg city number? Just asking as I don't know. Sounds like you may be estimating this tank by tank or by the A/Avg number.

    Third - The 0.01 lbs/min versus the 0.02 lbs/min ... there's just not enough granularity on those numbers to be able to actually distinguish that those are actually different numbers. Or different enough to know they're different. Difficult to describe my thinking. It's like one number is 0.01495 and the other is 00.01505 (and gets rounded to 0.02 because that's all the tool can display). So I consider that whole issue as a non-issue. Your mpg numbers seem good on these two cars so, I recommend you put those numbers out of your mind.

    Fourth - If the problem on your 2015 ES were something like a brake dragging, it would effect your highway mpg as well. If there is a true difference, it would be isolated to the dynamics to do with city driving. Since your highyway mpg on that car seems to be inline, I think I would base my final assessment on said vehicle to be based on overall average mpg of that vehicle versus the others. And I would not just (try to) isolate out the city mpg.

        __________________________________________

        click to view fuel log View my fuel log 2020 Mirage ES 1.2 manual: 42.4 mpg (US) ... 18.0 km/L ... 5.6 L/100 km ... 50.9 mpg (Imp)


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    Quote Originally Posted by Fummins View Post
    1. Are you basing these stats on hand calculated figure or just reading the cluster?
    2. Are you and your wife the only 2 people to drive your 4 cars?
    3. Why do you have 4 cars?
    4. A total shot in the dark here....if there are zero obvious variables(ie:driver,weather,tires(size-tread-weight etc..),brake dragging,then maybe try checking the charging voltage? There is a wire that runs from the alternator along the harness above the intake that is relatively common to break and make the alternator put out a constant 14-15volts and likely bogging down the engine a little more than usual. Sometimes the batt/alt warning light will turn on and sometimes the only way I know is via gps tracker that I once in a while take a look at to make sure nobody is driving obvliously with a bad alternator/idiot light on.
    5. I assume you've already checked or replaced the air filter at this point?
    6. is your new to you car a 5spd too? or did I miss that part? If so maybe replace the fluid? Wouldn't hurt if it hasn't been done and who know's maybe it's full of something thats too thick?
    1. calculated by hand... cluster on 2015 ES reads 34mpg
    2. Yes we are, I drive the 2020 ES and the 2014 DE, she the 2020 LE and the 2015 ES
    3. I am a hedonist... am worried about the 2020's which are being financed getting totaled while delivering and want to keep mileage low to keep 10 year 100000 mile warranty as long as possible so we bought a 2014 and a 2015 at insurance auction for pizza delivery.
    4. I went out and checked the alternator wire for 2 minutes (she was trying to leave for work) harness appears intact and unmolested. Are you recommending that I take the tape off and inspect the individual wires? Which wire am I looking for specifically? I thought I had read on the forum that the North American Mirage's do not have a "smart" alternator. The other day I did a voltage test on the 2020ES and 2014DE and both constantly put out 14-15 volts
    5. Air filter was replaced 3000 miles ago according to carfax records and to my visual inspection looks brand new.
    6. both 2020s and 2015 are cvt. We have scheduled an appointment with dealer to have programming for 2015 updated due to shift shock, they put out a TSB on it. According to Carfax the cvt fluid was last changed at 57000 miles (now 105000miles) and it was done at colony tire and not a mitsubishi dealership, Could they have used wrong fluid? why would this effect city and not highway?

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    Quote Originally Posted by 7milesout View Post
    First - All my responses are constructive, no criticism here. I just don't convey my thinking clearly so sometimes it sounds like criticism, but it is not.

    Second - How much data do you have to support the 28 mpg city number? Just asking as I don't know. Sounds like you may be estimating this tank by tank or by the A/Avg number.

    Third - The 0.01 lbs/min versus the 0.02 lbs/min ... there's just not enough granularity on those numbers to be able to actually distinguish that those are actually different numbers. Or different enough to know they're different. Difficult to describe my thinking. It's like one number is 0.01495 and the other is 00.01505 (and gets rounded to 0.02 because that's all the tool can display). So I consider that whole issue as a non-issue. Your mpg numbers seem good on these two cars so, I recommend you put those numbers out of your mind.

    Fourth - If the problem on your 2015 ES were something like a brake dragging, it would effect your highway mpg as well. If there is a true difference, it would be isolated to the dynamics to do with city driving. Since your highyway mpg on that car seems to be inline, I think I would base my final assessment on said vehicle to be based on overall average mpg of that vehicle versus the others. And I would not just (try to) isolate out the city mpg.
    2. tank by tank at the end of each delivery shift, so only half a tank is used when this is calculated. this is based on 5 fill ups one of which was 35mpg other four were 28mpg
    3. Thank you I will put that to rest in my mind now.
    4.The average mpg would still be 37mpg Which isn't terrible, so do you think that it shouldn't be of concern? I did a compression test when spark plugs were changed 150,160,155 Which is within specification according to FSM but still on lower side for this engine, Could that be a factor? Am I over thinking this?

  6. #6
    Alternator wire was a blind shot in the dark. Doubtful that's your problem. I'll assume it isn't.

    Some people claim mpg gains after cvt fluid change. I try to replace it on the fleet cars every 30,000miles(ish).

    I don't pay much attention to the average(trip b) lifetime fuel economy on the work cars. For my personal 2014's (both cvt)that I have owned, they were pretty close to the same. One car had about 30k miles(then engine was replaced under warranty for knocking) then I sold it last Feb when I bought my fancier one with 283k(176k miles) with a questionable cvt. It got similar fuel economy with that many miles as my lower mile car did. I replaced the engine(and cvt) with ones that had under 6000miles after it developed a bad rod knock. Economy went up slightly for a little while but I blame that on me trying harder and running the stock dunlops. I've been running taller 175/winter tires since last fall(ish) and manage around 40-43 mpg(mostly driving at 50-55mph). 28 seems awfully low.
    I'd consider a cvt fluid change and maybe replace(and inspect) both filters. Or at least replace the cartridge filter and drop the oil pan to get the most fluid out and inspect the pan for treasures.

    I just use universal cvt fluid that meets the J4 spec. Seems to work for me. These things are pretty picky about fluid level. FSM says to use a scan tool to measure fluid temp then compare to chart. I usually just measure what comes out and pour the same amount back in. When I do just a drop and not change any filters I usually get 2.5L(2.6qt) from the drain plug with the car level on a 4post hoist. That might be able to get you a rough baseline if you figure your level is incorrect?
    Mirage videos:

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 37.7 mpg (US) ... 16.0 km/L ... 6.2 L/100 km ... 45.3 mpg (Imp)


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    Just a thought, as I do mobile blood sampling and physicals, I spend quite a bit of time idling with the AC on. This will kill your mpg fast. Do you know if your wife is doing this when she's working?

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    Yes the car usually idles with the a/c on, and so do the others while delivering so I'm not sure why the mpg is that much different.

    Last night 7/27/22 she did not use the a/c at all, she rolled the windows down and never turned on the a/c, and the results were 2.303 gallons and she went 127.3 miles =55.28mpg....

    These figure seem a little ridiculous, but I talked to her through her shift and around 80 something miles she still was showing seven bars for the gas tank which means at 80miles she still hadn't used 2 gallons.

    Although she didn't use a/c car still idled a lot while delivering.


    So with all the fuel trim data, o2 sensor voltage and this, I guess we are left to examine the a/c.

    two things with the a/c
    1. does not blow as cold as the other three mirages, so I suspect it is low on refrigerant;
    2. the clutch on the compressor makes a clunking noise when car is started but is quiet when running.

    Could poor mileage be result of low refrigerant, a bad compressor, or both?

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    Quote Originally Posted by hkpotts1 View Post
    4.The average mpg would still be 37mpg Which isn't terrible, so do you think that it shouldn't be of concern? I did a compression test when spark plugs were changed 150,160,155 Which is within specification according to FSM but still on lower side for this engine, Could that be a factor? Am I over thinking this?
    At 37 mpg doing delivery, you're probably KILLING any other delivery driver's fuel expense. I don't know, but I believe lower compression would lead to lower mpg. Maybe not substantially lower, but lower. Lower power too, but again, maybe not noticeable except maybe if you were on a drag strip racing against an equivalent Mirage with higher CR.

        __________________________________________

        click to view fuel log View my fuel log 2020 Mirage ES 1.2 manual: 42.4 mpg (US) ... 18.0 km/L ... 5.6 L/100 km ... 50.9 mpg (Imp)


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    Quote Originally Posted by hkpotts1 View Post
    Could poor mileage be result of low refrigerant, a bad compressor, or both?
    In my opinion, with low refrigerant and cycling of the compressor, the mpg would be higher. Due to there being time when the engine does not suffer the compressor load. If the compressor were going bad, maybe it could lower the mpg, but I think you'd probably be hearing some odd noises when the compressor is running.


        __________________________________________

        click to view fuel log View my fuel log 2020 Mirage ES 1.2 manual: 42.4 mpg (US) ... 18.0 km/L ... 5.6 L/100 km ... 50.9 mpg (Imp)


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