2006 Mitsubishi Lancer - Sudden Increase in Fuel Consumption After Getting Timing Belt Changed

Ozbargainers, I'd like your opinions please. Background info: I own a 2006 Mitsubishi Lancer 2.0L Sedan, currently sitting at around 187,000km. On a fuel-up of ~38-40L, I could usually average between 500-550km.

On 11/2, I took my car in to my local mechanic for a minor service, and got the timing belt changed on 13/2. Between those 2 days, I barely drove the car. Immediately after getting the timing belt changed, I noticed an increase in the fuel consumption of my car, but thought it was perhaps an error in the fuel consumption gauge (like what happens when the car starts/ends on a hill and gives a false reading). I went overseas between 18-27/2, and the car was left idle in the driveway of my home during that period. Once I arrived home, I drove to and from work as usual, and noticed that there was a definite change in how many km I could go over a full tank (~300km from a full tank).

I took the car in to the mechanic on 1/3, and the guy looked around in the bonnet of the car and did some computer scan, and all came back clear. I mentioned that the fuel consumption had increased post-timing belt change, but he refused to check out the timing belt "because it would take a whole day and I don't have time for that". He then told me to monitor fuel economy over the next 2 full tanks. I did so and recorded 361km on 38L, followed by 420km on 37L. I took these figures (with photos) to the mechanic and he said he had no idea what could be wrong with the car, and that he couldn't help me (and still refused to check the timing belt). He put it down to erratic driving behaviours or bad batches of fuel. FYI my driving behaviours have not changed, nor are they erratic. I fueled up all 3 times at my local Woollies Caltex with 91ULP.

My question: is this normal after getting the timing belt changed?? I'm currently monitoring how far my car goes on the 4th full tank, since there was a big increase between the 2nd-3rd tanks.

TLDR: got timing belt changed, noticed significant decrease in fuel economy. Fuel economy improved over 3 full tanks, but is not yet what it used to be. Is this normal vehicle behaviour after getting the timing belt changed, or should I get a second opinion?

Edit: Unsure if any of this information is relevant, but.. The mechanic and my dad have a longstanding good relationship. The mechanic has previously stated that my car runs surprisingly well compared to other vehicles of a similar make/model/year. When picking my car up after getting the timing belt changed, the mechanic said that my car strangely had 2 timing belts and some hydraulic tension thing (sorry, unsure exactly what it was due to poor memory), and I paid around $450 for the parts + labour (this was separate to the service). Could be chinese whispers, but I have also heard recently from my mum, who works with a lady whose husband is a mechanic at a dealership, that he gets frequent calls from my mechanic with questions on what to do as he is apparently clueless.

Comments

  • +2

    It's a pretty big job to replace timing belt. I wonder if all the sensor connectors were put back in place correctly. Normally check engine light would come on though.

    • Check engine light hasn't come on, and car is running pretty smoothly, so I have no idea what to do :(

      • +4

        take it to a RAC mechanic… if you're a member they do a free fault find and report once per year. could be a blocked fuel line/filter… once fixed or self rectified… would increase fuel consumption. P.S. your mechanic is not god… do not treat what he's says as gospel.

        • Damn I didnt know about the free fault find and I've been a member for 4+ years now.

          Could have saved me a bit of a hassle but thankfully I've had a good mechanic.

          edit : I'm reading now that you need to have a breakdown first (or so it says on the process, could be just an example). Could you clarify? Thanks!

        • @lolbbq: Sounds like you are having a breakdown. đŸ˜‰

    • +1

      I wonder if all the sensor connectors were put back in place correctly.

      A sensor fault should've shown up on the OBD scan.

      However, mechanic incompetence won't.

  • not normal, thats a big difference.. car ecu/computer when reset willaffect fuel consumption but not taht much . probabaly some timing sensor issue.

    do you notice any performance ad power issues?

    • Nope, car is running very well, just like before.

      • +1

        Ensure you are reading the petrol usage correctly by filling up to the click, drive say 300kms, then fill up to the click again and calculate amount of litres. Don't go by the fuel gauge. Note your l/100kms

        Bit hard to go by internet descriptions but it's possible that the o2 sensor/temp is faulty causing the engine computer to run really rich. Means will use up heaps more petrol. Just taking a guess really.

        Good luck

        • Ahh that's a good idea, thanks for that. I only thought of recording litres filled up and the km, but I guess it'd be easier to compare if either of the values was constant.

        • @lizzle:

          Were you filling the tank to the brim each time?

        • @Scrooge McDuck: yes, I was

      • Don't worry, i think it's pretty normal as usually those new bearing, pulley and tensioners are pretty tight compare to the old ones. monitor it for another few more tanks of petrol, after running in, your fuel consumption should improve.

        btw, $450 is a very good price for timing belts change.

  • +6

    You're claiming approx 7.2 litres to the hundred pre timing belt change. That's almost Prius territory, I think your old figures are incorrect.

    • My sister's husband is a mechanic and took meticulous care of the car prior to selling it over to me. Not sure how it ran so well, but I'm just stating the average figures I had been experiencing in the last 1.5 years of ownership.

      • Could you outline your methodology for calculating fuel consumption?

        • +2

          I'm not sure if it's the best thing to do for the car, but usually I let my tank run pretty empty before filling up, and 90% of the times that ends up being 35-38L of fuel, which almost always reads as 480-530km, and sometimes up to 550km (I reset the counter each time I fuel up out of habit).

    • +2

      Mate Prius territory is mid to low 4's. 7.2 for a small car such as a Lancer is honestly pretty standard, if a little low. (But that can be explained through hoe the car is used, such as with more motorway commuting)

    • Quite achievable if you drive a lot of highway kilometres and don't drive like an idiot (most drivers). I average 6.9l/100kms in my partner's CJ Lancer (verified via ScanGauge), but we don't live anywhere near the city and its overpopulated roads.

    • 7.2l per 100km is bad for my Mazda 3. I'd hope a Prius gets better than that.

  • +5

    You are very right in questioning this issue. No, absolutely not ….your Fuel Consumption/Economy will only improve on a new belt, just a touch if at all, but improve, not be worse by nearly 35%. The tensioner should take up any slack or out of adjustment of the old belt prior to the change.

    So, your engine should should slightly more difficult starting and or a significant power change if the belt was not installed correctly, ie out a tooth or two, before it was running so erratic it would not of left the workshop. So, my guess will be in some other Engine Control device or sensor that was jiggered with during the work.

    I have not seen this much difference in fuel numbers re a timing belt where the car is still drivable. Keep all records, pics of odometer, and fuel receipts etc. Ask Mitsubishi Service dept for a response, and also another workshop for a quick appraisal or point of view. Or even a few. Get your sisters hubby to do an appraisal as well, and get it in writing.

    After say another 3-4 tanks of controlled refueling and data recording, and with the advise you have received from other workshops, it should show in your favour that there is something amiss severely affecting the fuel usage, but not much so in drivability. Once you know what is what, give them a chance by hitting the original workshop up for either the vehicle to be repaired properly, or redo the entire job again free of cost, or fully refunded all costs so far, but you drive away with the problem to be repaired elsewhere.

    Sounds like getting decent repairs and half decent customer service is near impossible down below the border. Your mechanic suck for the many complaints and disgusting attitude they reply back with. My apologies on behalf of all mechanics that do not warrant their work 100%.

    • Thank you for the detailed response. I'm currently living in QLD, whereas my sister and her hubby are in NSW; otherwise I'd obviously just go to the brother in law for all my car work to be done. What you've said to do is exactly what I had been planning. I just wasn't sure if I was overthinking things, or if there actually was a problem. Furthermore I figured it'd cost a few $$$ to get it checked elsewhere since it sounds like it does take a fair chunk of time, so I was after confirmation that it was necessary before I went ahead.

      • +1

        I probably should said a bit more on that point. You want to get as many non intrusive and not strip the engine down again type of quotes/tests done. Checking the basic timing belt marks does not mean a full front of engine off to see, just some and we are not talking spending mega each workshop.

        But also, Repco AutoTech has a fault history online database and lotsa stories and experience to draw from the many good workshops on their data base of online tech users. When you get to one, have them put your story up to ask hundreds of mechanics all at once.
        Good luck. PS, nail that ignorant original workshop manager, warranty work is priority work, he MAKES time!

    • All sounds great but you got buckleys of proving the mechanic did anything wrong. If the car is running fine with no faults whatsoever there is nothing to prove wrong.
      Its generally accepted that Fuel consumption can vary with every tank full. Too many variables in play.
      Could by chance be a sensor playing up as others have said but not the fault of the mechanic. Just co-incidence.
      I would focus on trying to identify the problem, if indeed there is one, rather than trying to pin something on the mechanic. You wont win.

      • +2

        To a point I agree, as I have put a lot of effort into writing buckets of useful information on methods to do exactly that - find the fault. Also the OP has more than just the fuel consumption issue to deal with.

        I, as with everyone else concerned, have absolutely no reason to doubt or exclude the OPs claims.
        He sounds very switched on what he found and what he did to check by the numbers, I have no doubts.

        A average 25-35% loss of economy is a major fault which only occurred after the moment the Timing Belt Service was performed. In all my years, warranty is always the thought….a workshop fault until or unless proven otherwise. BTW, 95% of the time, faults as this are/were always my staff, the parts, or something we missed in asking the customer, and the balance was actually a vehicle fault that was out of our control, ie coincidence.
        Remember as I stated, my customers come first, not Mr Buckley.

        But as a career mechanic with multi national workshop supervisory and well as my own workshop experience, you should never expect less than 100% exceptional customer service and satisfaction.

        Regardless of the chances, or what/who is the creator of the issue, we always give customer service first, and blame others last.

        All the mechanic had to do was admit the excessive fuel consumption is an issue. Ask questions to ascertain any useful info on what where when and how from the vehicles history, service, repair and owner/driver info. Then advise how soon he could go over all his work, and advise if it is warranty it is absolutely free, and if there is an other fault, coincidence or otherwise, a conversation can be had to sort the costs.

        That is good business, chance plays no part. Sorry, I do not think your doubting comments were helpful to the OP or anyone else.

        • doctordv8. This is REALITY!
          OP didn't ask for an advertisement from you about your wonderful mechanical services.
          You obviously know that the same rules do NOT apply in every workshop as this is how you distinguish your services. Thats great for you and your customers but it doesnt help OP at all.
          I stand by my comments because its REALITY !
          OP will be wasting time and money trying to prove the mechanic did something wrong. A complaint to Fair Trading will go nowhere because the mechanic's defense is clear cut and straight forward as I already stated.

        • @Amayzingone: totally agree

        • @Amayzingone:
          How can you be so blind to what I wrote?
          I never once advertised my services, you have no clue to my real or trade names. Therefore I never tried to give the OP anything from me except advise on the few different issues he has.

          You are sadly suffering from poor service acceptance or such because you appear to accept that is normal. Proving whether the mechanic was automatically at fault and therefor should /will pay was never the main issue, if you actually read all comments correctly before getting hot under the collar.

          Getting to the fault was and is the main issue, and the various methods to get there. Saying what the mechanic should of done and perhaps what he still might do is info for the OP, as it is still his duty to accept there may be a warranty issue. That is true reality.

          Please read carefully what people that help actually say, and not what you think we are saying. Calm down fella! I hope one day you get some good service and or a warranty due, to show you what realistic good customer service is. Have a nice day, and please stop annoying us with your rants. You are not helping…still.

  • +3

    That Mitsubishi has a hydroloc tensioner and a large timing belt and a smaller belt as a balancer. It's standard. The engine still operates without the smaller one though

    • Probably just goes to show how clueless my mechanic is, since he said it's very strange and unusual for it to be like that. sigh

  • how tight are your auxiliary belts?

    • I honestly have no idea what that is or how to check it :(

      • Ask around for a more reputable mechanic and get him to check it over. Might cost a few $ but will be worth it for peace of mind to know if the job was done right.
        If your old mechanic is calling around to ask how to do a belt change on a 10 y/o lancer then just stay away.
        Your economy seems to be improving though…

      • Engine fan and aircond belts should have some flex in them. Not too loose mainly. I doubt this is related to heavy fuel use increase.

  • I think you might need to scientifically recheck the accuracy of fuel usage paricularly against similar vehicles, make & year. Let us know.
    Do you think your computer tuning may now be out? Needing to be retuned.
    Or as others have said an O2 or other sensors were not reconnected.
    Best of luck as this can be frustrating.

    A couple more points, maybe check your engine number (engine swap?), and check for fuel leakage. Does car roll down hill normally (if M/T).

  • Simple

    Take a trip down the border and have your B in Law check out the car. As you said he was meticulous in maintaining the car.

    Frankly I am surprised he sold you a car that needed the timing belt changed. While different models have different requirements, a google shows lancers have 15Km service intervals and 90000 recommend timing belt changes .

    So I would be surprised a meticulous mechanic like your B-in-L hadn't changed this b4 you bought it (especially with family). Unless you bought it years ago with much less km's on it.

    • The timing belt was last sold at around the 90,000 mark, and I bought it at 150,000km. I guess it was just time for it to be changed. And while I would like to drive it down, I don't have the time required to do the 13 hour drive there and back due to work, unfortunately.

  • Timing belts should be banned. Why don't all engines have timing chains? Is it a cost thing, what, $10 more expense for a chain over a belt, or a mechanical design reason?

    • +1

      Less noise perhaps? My car has a belt between the crank and the exhaust camshaft, and a chain between the exhaust and inlet camshafts.. It's not onerous to change the timing belt though, however that chain would be a nightmare to get to.

    • They used to be chains. Moved to belts for fuel economy and better throttle response reasons. Lately its been back to chains for maintenance reasons. Both require maintenance but chain is more reliable. Good engines are non interference. This means when the belts break, doesn't mean you have to replace the whole engine. This is also why I like Toyotas engine designs.

      • Yes, if it's a simple matter to change the belt they might even be better than chains. On some cars, however, it takes a lot of hours and a lot of money to change the belt.

      • the fuel economical engines are actually interference with higher compression. Most of the new model cars are interference

    • Chains stretch and can snap. It happened to me on a Mercedes in a chain that was never meant to be replaced.

    • Because timing chains are just as evil for their own reasons and 5 x the expense to repair.

  • When I had my timing belt changed (Subaru Liberty), the mechanic forgot to reconnect the two thermostatically controlled fans on the radiator. About 6 months later when I was pulling up a steep hill on a hot summer day, the radiator exploded!!

    • Well crap, hoping that doesn't happen to me!

  • +3

    When the cars computer is reset, usually after the battery has been disconnected for a while, it takes a couple of tanks of fuel to relearn the timing and fuel trim values. Usually pretty…not rough, but not refined for the first few hundred kilometres and then get better. You've said it got better by the second tank, just see how it goes.

    Others have suggested that some sensor is disconnected, but if there was a disconnected sensor, the computer would throw up an error. So I doubt its that.

    On that second tank you are getting 8.8L/100km. That's not bad for a NA 4-cylinder 11 year old car. My parents 2013 Jetta with its 1.4L twin charged 4-cylinder only does about 7L/100km

    • it takes a couple of tanks of fuel to relearn the timing and fuel trim values.

      That would be a pretty damn slow ECU…

      • It's not being slow.. the ECU takes time before jumping in to a conclusion just by few full tanks. My Prius did that after a battery reset and it took almost 6 full tanks to fuel economy value on the dashboard to be settled in good old values..

  • Do you know if he removed the battery? Maybe the ECU was reset and may need to be tuned again. Get a second opinion from another mechanic or take it to Mitsubishi.

    • I'm not sure. I'm planning to check how many km I do on the current tank before I take it to a Mitsubishi dealership.

  • +2

    Could be chinese whispers, but I have also heard recently from my mum, who works with a lady whose husband is a mechanic at a dealership, that he gets frequent calls from my mechanic with questions on what to do as he is apparently clueless.

    Is your Mum Chinese?

    • haha no she's Korean, but it was just a figure of speech.

      • Just trying to rule things out to troubleshoot the problem. :)

  • I assumed this was completely unrelated (and probably is) but could the mechanic also have done something which would make my little Pioneer stereo system pop, shut down and cause a burning smell for ~10 seconds? It happened maybe 3 days ago, and mechanic said all was fine with the car. Stereo system worked like usual when I turned it back on, and it hasn't happened again since. He couldn't explain why it happened (in fact I think his exact words were "sometimes things like that happen, but there's nothing wrong with your car"). Is that true?

    • +1

      probabaly stereo system install issue. somtimes the wiring harness rubs onto some metal parts inside the car from vibration causing issues with electricals. smoke means its quite bad.

      also check your fuses to make sure none installed are over the manufacturer amps.

  • +6

    Something you said made my ears prick-up.

    I'm not sure if it's the best thing to do for the car, but usually I let my tank run pretty empty before filling up, and 90% of the times that ends up being 35-38L of fuel, which almost always reads as 480-530km, and sometimes up to 550km (I reset the counter each time I fuel up out of habit).

    When you let the fuel-tank 'run on fumes' before re-filling it can suck whatever gunk, rust, dirt, even water from the bottom of the tank.
    If you believe the fuel that comes out of the pump is clean, your wrong.
    I rarely let my car run down to below 1/4 to avoid having to replace fuel filter.
    This just MAY be your problem. Also the easiest to rectify.

    Just a thought.

    • Alright thanks, I'll make sure it doesn't get too low from now on.

    • Good advice.

  • +1

    You haven't mentioned any change to performance so I assume car is running normal.
    NB 2006 model is actually a 2.4L model. Not 2.0L as you stated.
    This bigger engine consumes much more fuel than the old 2.0L engine.
    Hence 420km on 37L is pretty good for this car.

    • I have a Lancer 2.4L automatic wagon and I get approx 9.5/10 liters per 100km constantly. The wagons with auto are known to be the worst for fuel economy out of all of the 2.4L lancer variants, so if yours is not one of these then I woudl suggest something is afoot.

  • +1

    This might sound stupid and totally unrelated but I would change the fuel cap. Once they get a bit old they don't work properly as the vent stops working. This can cause many fuel problems leading to higher fuel consumption. Only about $15 for a fuel cap. Just mention this from past experience with 2 cars!

    • Thanks for the suggestion :)

  • Pose the question on ecomodder.com. There are some incredibly knowledgeable blokes on it.

  • I think it just needs some time for the car to get the averages back up to the "normal" level. If you've been doing mainly city driving since the repair, then obviously the trip computer will show a lower efficiency. The previous figure of 500 was an average that would have come from a mix of city and country driving done since the last reset. As you mentioned, the figures seems to be going back up anyway.

    Same thing happened to me when I replaced my car battery a couple of weeks ago, the figures are still coming back to the previous averages.

    I'd be worried if its still the same after a couple of months of driving.

  • +2

    My father replaced the timing belt on his camry 2003 almost 5 years ago. Until this day he claims that his car is using more fuel than before and he keep saying that he regret replacing it. So yeah i guess you can be friend with my father.

  • +1

    I would eliminate the obvious problem first .. fill up at an alternate station and see how the economy varies.

  • When replacing the timing belt, the timing will require setting with a light gun. It could have potentially been retarded by a degree from manufacturers specs resulting in higher fuel consumption and sluggishness, assuming none of the teeth was jumped as well. Depending on engine, taking the cam cover off to verify timing could be an hour job or a half day job. FF cars typically longer. Not sure if your car has EGT sensors. But a higher than normal EGT will indicate retarded timing.

    Does the car feel sluggish?

  • +1

    My wife's 2006 Lancer has a 2.4 litre engine. Sure yours is 2.0?

  • +2

    How are you getting your fuel consumption data?

    If it from the dashboard, it is probably just from the ECU relearning your driving style. The totals reset when the battery is removed.

    Quite often your distance to empty reading is an average of the time since it was last reset, including all highway kilometers​.

    Highway kilometers use significantly less fuel.

    Dash readings are not very accurate anyway, and are mainly PR.

    If you are doing the calculation yourself, and had been prior to your service, litres filled / kilometers travelled, keep recording this and see if it changes.

    If you're just using the dashboard reading, wait it out it will change back.

    • This model Lancer doesn't have a fuel consumption readout on them, so he woudl be doing it manually.

  • I used to have the same model Mitsu. Didn't have this problem.

    But I did take it for servicing at my local mechanic, as opposed to Mitsu service centre.

    Unfortunately, the local did a terrible job servicing it. It developed a loud whine in the alternator. The mechanic said gotta change it ($1000+). Took it to another mechanic, without saying what I thought the problem was. Same result.

    Took it to mitsu (it was just on 2 years old), they jacked it up, blew high pressure air into the alternator. Came out without the whine and no cost.

    Never went back to local mechanic.

    Bottom line for me - always take the car to the people who made it, if you want it serviced properly.

    Just my 2 cents.

  • i've gone through all the posts here. what i think you should do is contact your brother in law. send him photos and pics/video chat to quickly isolate easy issues such as sensor disconnections, engine sounds.

  • +3

    Ring Raa and say the engine light flashed then went away and you don't want to keep driving just in case. They will 100% come out and scan for error codes. This will 100% rule out sensors etc.

    If no issue found, disconnect the battery and reconnect to reset ecu. Like any comp, a reset is needed from time to time.

    Lastly, and most like here, I suspect your issue is the fuel. I have found on a couple of occasions Woolies to return the worst economy figures. Petrol stations are now allowed to add up to 10% ethanol to Ulp91 without notification. Reset battery and fill up elsewhere. I bet everything will be back to normal.

    Oh and lastly. Are you carrying more weight? For example, an extra passenger more often than before. Heavy stuff in the boot. This will obviously effect fuel numbers.

  • +2

    In addition to the ECU reset, you may want to consider:

    1. Oxygen or MAF sensors on the way out - can cause excessive fuel use
    2. Spark plugs may require replacement - not burning fuel as efficiently as it should
    3. Are you using identical fuel to test? ensure your test is controlled, also beware of "dodgy fuel"

    As other posters have mentioned, check timing advance and avoid running your tank too low.

    Also, don't forget to check tyre pressures. And are you driving around with AC on (increase fuel consumption from running the compressor) or windows down (can increase drag at high speeds, thus higher fuel use).

    Being a 11+ yo car, you should expect to begin replacing things as the car ages. Corrosion, carbon build up, and general parts failure (especially sensors and suspension components) are normal and expected.

    Good luck and enjoy!

  • Swapped O2 sensors will result in poor economy but will not throw an error.

  • Like others have pointed out.
    Most likely oxygen senor is dead.

    • Worth renewing an oxy sensor every 80k

  • Just wanted to say I had one of the new shape CJ Lancers when they first came out, I test drove one auto and one manual in 2.0 guise and between them they got 9-10 litres per hundred consistently in urban (fuel fill-up measurement). Extra urban, maybe shaved off 1-2 litres or so depending on how much cruising was done. I settled on the manual version.

    Nothing to see here really. Be happy with under 10L per hundred in a 2.0 petrol motor. I'm currently driving a few year old 2.0L diesel and getting between 6 and 7L per hundred no matter how I drive. Nice change from what I'm used to.

  • +1

    First fuel consumption reading = 8.0L/100km
    Last fuel consumption reading = 8.8L/100km

    Doesn't sound like there's a jump in consumption; there could be a number legitimate of reasons for the minor difference between two tanks.

    8-10L/100km is perfectly reasonable for a 2L (or 2.4L) too.

  • Lizzle, there are idiotic and nasty/sarcastic uneducated responses which I have received on your problems, for actually trying to help you. With over 37years of experience, in exactly your issues, and in Fair Trading, and Workshop managing, Trainee supervising and running my own until semi retirement recently, as well as Investigative research on vehicle issues, I stand by everything I have said to you. I bow out as I see you have quite a lot of good assistance from many experts and others, if you weed out the rubbish. Good luck.

  • No one has mentioned the oil yet. Maybe its been filled with 20w50 and used to be running 10w30 ? Also check the battery, after sitting for weeks it maybe down on charge and the alternator isnt giving enough and dragging down the consumption. Once a ca ca batt has flattened its never the same, but sometimes a day or 2 on charge will pick it up

  • It sounds to me like your timing belt is out a tooth, get someone to whip the covers off and double check timing marks line up. Normally I'd expect the car would be running a bit rough if this was the case.

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