Fuel economy decreasing over time... causes?
10-20-2009, 04:08 PM
#26
Footy, Have you looked in the repair manual Pages 103-109 under Poor Fuel Economy.
2.Engine Troubleshooting.pdf
http://www.hi-impact.org/ryang/modif...ineProblem.pdf
2.Engine Troubleshooting.pdf
http://www.hi-impact.org/ryang/modif...ineProblem.pdf
10-20-2009, 06:19 PM
#30
What I mean to say is... I will try to do one tank at under 5000 rpm to see if I can get the "375 km / tank (till light comes on)"...
If I do, then it would prove that the coils are still somewhat good at 51,000km stock original coils.
If not, then I'll check out the coils. I think coils and plug wires are easy enough as a DIY right guys? With our dollar almost at parity, it is a good time to buy stuff online... and if I do, yes I will start a group buy thing, as ROtarygreg wanted something too.
Onto the topic of general wear and tear, that was also my list. I simply don't know how long rotary engines last compared to piston engines at high RPMs... What I mean precisely is apex seal life... overtime, the engine will fail from age and will require a set of new seals all around.. apex, oil seals, side seals etc... a rebuild essentially. But those are factors I can't control.
If I do, then it would prove that the coils are still somewhat good at 51,000km stock original coils.
If not, then I'll check out the coils. I think coils and plug wires are easy enough as a DIY right guys? With our dollar almost at parity, it is a good time to buy stuff online... and if I do, yes I will start a group buy thing, as ROtarygreg wanted something too.
Onto the topic of general wear and tear, that was also my list. I simply don't know how long rotary engines last compared to piston engines at high RPMs... What I mean precisely is apex seal life... overtime, the engine will fail from age and will require a set of new seals all around.. apex, oil seals, side seals etc... a rebuild essentially. But those are factors I can't control.
10-20-2009, 06:46 PM
#31
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What I mean to say is... I will try to do one tank at under 5000 rpm to see if I can get the "375 km / tank (till light comes on)"...
If I do, then it would prove that the coils are still somewhat good at 51,000km stock original coils.
If not, then I'll check out the coils. I think coils and plug wires are easy enough as a DIY right guys? With our dollar almost at parity, it is a good time to buy stuff online... and if I do, yes I will start a group buy thing, as ROtarygreg wanted something too.
Onto the topic of general wear and tear, that was also my list. I simply don't know how long rotary engines last compared to piston engines at high RPMs... What I mean precisely is apex seal life... overtime, the engine will fail from age and will require a set of new seals all around.. apex, oil seals, side seals etc... a rebuild essentially. But those are factors I can't control.
If I do, then it would prove that the coils are still somewhat good at 51,000km stock original coils.
If not, then I'll check out the coils. I think coils and plug wires are easy enough as a DIY right guys? With our dollar almost at parity, it is a good time to buy stuff online... and if I do, yes I will start a group buy thing, as ROtarygreg wanted something too.
Onto the topic of general wear and tear, that was also my list. I simply don't know how long rotary engines last compared to piston engines at high RPMs... What I mean precisely is apex seal life... overtime, the engine will fail from age and will require a set of new seals all around.. apex, oil seals, side seals etc... a rebuild essentially. But those are factors I can't control.
i drifted from my point there. changing your driving style is no way to determine if you do in fact need coils. the only half decent way to tell if you need them is to have someone in the know, IE scarborogh mazda or myself/guelph city mazda, do a spark test on the car.
Now these spark testers arent technologically advanced. you need specific experience to understand what you see. there is no gauge or computer to tell you the meaning of what you are seeing. however it will highlight any weak coils instantly. and if you know from experience what a great spark as opposed to a passable or even weak spark looks like, even better. You are going about this the wrong way to diagnose your problem.
as for the engine wear thing. you are going to go crazy if you look at your car like its a ticking time bomb. its only got 50k on it. you arent even close to where you should be worrying about that. ive got 107 on mine. original engine, and maybe 20k on new plugs coils and wires. i compression tested mine a few months back and it was within spec and i dont baby my car. yours should be well within spec still compression wise. coils are something different all together. they seem to all be very weak by 80 000km however they do also seem to die randomly as well. heat and vibration are what kill a coil and guess what our engines love to do? get really stinkin hot and vibrate like crazy. lol. that and the fact that the coil is firing almost constantly without any sort of rest until the car is shut off. at least on a piston engine with coil on plug you get three strokes of rest before the coil is fired. ours just constantly dwell, fire, dwell, fire, etc.
you are over thinking the living hell out of this. its great that you monitor fuel economy. we all should every tank. its a great way to know that something isnt working the way it should before it leaves you stranded/flooded. however you cant use your fuel mileage to determine whats wrong with the car. there are all sorts of tests that can be done to determine why your mileage isnt what it should be. but more importantly, you have it on record on this very website that 99/100 times, when your fuel milage goes south you need either plugs, coils, wires, or a combination of them.
so let me know if you want to come down to guelph for me to do some tests on your car. otherwise, go see scarborough mazda about it. know for sure before you throw the parts at it.
Last edited by rotarygreg; 10-20-2009 at 06:51 PM.
10-20-2009, 07:13 PM
#34
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i feel somewhat sorry for you andrew. in a world where the simplest explaination is almost always right one, you are overthinking all this by leaps and bounds.
10-21-2009, 10:00 AM
#35
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If I do, then it would prove that the coils are still somewhat good at 51,000km stock original coils.
If not, then I'll check out the coils. I think coils and plug wires are easy enough as a DIY right guys? With our dollar almost at parity, it is a good time to buy stuff online... and if I do, yes I will start a group buy thing, as ROtarygreg wanted something too.
Onto the topic of general wear and tear, that was also my list. I simply don't know how long rotary engines last compared to piston engines at high RPMs... What I mean precisely is apex seal life... overtime, the engine will fail from age and will require a set of new seals all around.. apex, oil seals, side seals etc... a rebuild essentially. But those are factors I can't control.
If not, then I'll check out the coils. I think coils and plug wires are easy enough as a DIY right guys? With our dollar almost at parity, it is a good time to buy stuff online... and if I do, yes I will start a group buy thing, as ROtarygreg wanted something too.
Onto the topic of general wear and tear, that was also my list. I simply don't know how long rotary engines last compared to piston engines at high RPMs... What I mean precisely is apex seal life... overtime, the engine will fail from age and will require a set of new seals all around.. apex, oil seals, side seals etc... a rebuild essentially. But those are factors I can't control.
The one other thing you have to consider is your driving habits / routes. I'm not sure about when you're compairing your milage, but I know you moved a little while ago into a densely populated area with uber traffic. Having to sit at more lights and the constant accelleration / braking will most definately effect your milage.
I drive almost exclusively back roads at this point and I get about 275 to a tank where as others who drive hwy will get significantly more. Hell.. the few times that I have driven highway (ie road trip to Ottawa) I've managed to get 280km out of just slightly over half a tank.
Food for thought
10-21-2009, 01:19 PM
#36
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The highest i got for MPG was like 420-450kms when i went to buffalo, and i wasnt babying it either. I did 160 most of the way there as were a bunch of other people, i was going with the flow :D, till a cop showed up and caught one of us. Anyways, other than that i get like 300-320 till the light turns on and my car is 71k.
If you read my other thread you might know i might be in need of some plugs and coils soon too so dont forget to include me in the group buy!!!
If you read my other thread you might know i might be in need of some plugs and coils soon too so dont forget to include me in the group buy!!!
10-21-2009, 05:01 PM
#37
Rev,
That is true. I have much more stop and go traffic now as I drive exclusively local to go to work and they are the worst routes too... (Yonge st... then Centre st. then Hwy 7).
Hwy 7 isn't that bad but it's only the last 3km of my drive. WHen I used to live in SCarborough, it was Hwy 401 and then Hwy 404 which is pretty good in the morning, and then Hwy 7 which has very few lights compared to the traffic on Yonge st.
Maybe, this could be a reason...
Aside from fuel consumption, the car performs beautifully and drives fine...
That is true. I have much more stop and go traffic now as I drive exclusively local to go to work and they are the worst routes too... (Yonge st... then Centre st. then Hwy 7).
Hwy 7 isn't that bad but it's only the last 3km of my drive. WHen I used to live in SCarborough, it was Hwy 401 and then Hwy 404 which is pretty good in the morning, and then Hwy 7 which has very few lights compared to the traffic on Yonge st.
Maybe, this could be a reason...
Aside from fuel consumption, the car performs beautifully and drives fine...
10-21-2009, 05:03 PM
#38
Rev,
That is true. I have much more stop and go traffic now as I drive exclusively local to go to work and they are the worst routes too... (Yonge st... then Centre st. then Hwy 7).
Hwy 7 isn't that bad but it's only the last 3km of my drive. WHen I used to live in SCarborough, it was Hwy 401 and then Hwy 404 which is pretty good in the morning, and then Hwy 7 which has very few lights compared to the traffic on Yonge st.
Maybe, this could be a reason...
Aside from fuel consumption, the car performs beautifully and drives fine...
That is true. I have much more stop and go traffic now as I drive exclusively local to go to work and they are the worst routes too... (Yonge st... then Centre st. then Hwy 7).
Hwy 7 isn't that bad but it's only the last 3km of my drive. WHen I used to live in SCarborough, it was Hwy 401 and then Hwy 404 which is pretty good in the morning, and then Hwy 7 which has very few lights compared to the traffic on Yonge st.
Maybe, this could be a reason...
Aside from fuel consumption, the car performs beautifully and drives fine...
10-21-2009, 10:23 PM
#39
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Rev,
That is true. I have much more stop and go traffic now as I drive exclusively local to go to work and they are the worst routes too... (Yonge st... then Centre st. then Hwy 7).
Hwy 7 isn't that bad but it's only the last 3km of my drive. WHen I used to live in SCarborough, it was Hwy 401 and then Hwy 404 which is pretty good in the morning, and then Hwy 7 which has very few lights compared to the traffic on Yonge st.
Maybe, this could be a reason...
Aside from fuel consumption, the car performs beautifully and drives fine...
That is true. I have much more stop and go traffic now as I drive exclusively local to go to work and they are the worst routes too... (Yonge st... then Centre st. then Hwy 7).
Hwy 7 isn't that bad but it's only the last 3km of my drive. WHen I used to live in SCarborough, it was Hwy 401 and then Hwy 404 which is pretty good in the morning, and then Hwy 7 which has very few lights compared to the traffic on Yonge st.
Maybe, this could be a reason...
Aside from fuel consumption, the car performs beautifully and drives fine...
And REMEMBER, 1st gear, 8km/h no throttle auto drive (without gas pedal at all)...and 2nd gear, 12km/h throttle auto drive.
This two tips will enable you to be in constant motion even in stop and go traffic(highway) if you time it properly, hence reducing the stop go gas burning routine...
But if you got tons of lights...oh well you're SOL. :P
10-22-2009, 10:19 AM
#40
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As Rev pointed out, you are probably noticing the extra consumption due to your new location by the sounds of it. If she is running fine, no hesitations etc...then doubt there are any problems. I have extra couple sets of coils you could borrow for a week to see if that makes a difference, but doubt it.
If you are worried about fuel economy and the winter coming...buy a beater...woot woot to savings I found the 8 is really bad on fuel in the winter.
If you are worried about fuel economy and the winter coming...buy a beater...woot woot to savings
I found the 8 is really bad on fuel in the winter.
10-22-2009, 11:46 AM
#41
Thanks for all your input guys,
I will try the highway route which is slightly longer in mileage, but far less stop and go, and takes about the same amount of time to/from work...
Try to replicate driving conditions before I moved to North York so to speak...
On a side note.. one time I filled up gas at Sheppard and Warden, and moved 9km westward on Sheppard in stop and go traffic all the way to Sheppard and Yonge. In that short 9km distance, my fuel gauge moved down one notch
City driving really kills the car's fuel economy
I will try the highway route which is slightly longer in mileage, but far less stop and go, and takes about the same amount of time to/from work...
Try to replicate driving conditions before I moved to North York so to speak...
On a side note.. one time I filled up gas at Sheppard and Warden, and moved 9km westward on Sheppard in stop and go traffic all the way to Sheppard and Yonge. In that short 9km distance, my fuel gauge moved down one notch
City driving really kills the car's fuel economy
Last edited by Footman; 10-22-2009 at 11:48 AM.
10-25-2009, 08:03 AM
#43
Update: Driving Style
Yesterday on my drive to the sherway meet I filled up with Sunoco 91 I habitually use Shell V-Power 91, but it was on the way. Approximately a 120 km round trip with mix driving of side roads @ 70-110 km and highway @ 110-130 with bursts close to 149 km with no stops other than lights. For the first time in ages I got 120 km out of the first quarter tank, my normal lately is 70-85. I believe what is killing my fuel economy is the stop/start/idle I do on the 404 everyday I drive the car that route.
I'm still going to change out my/plugs/wires/coils in the spring but truly don't believe I'll see a significant increase in my fuel economy with ever growing traffic congestion in the GTA.
But you never know it could the change to Sunoco 91, but I doubt it. In short I generally don't pay that much attention to my mileage (you get what you get attitude) but if this is truly the culprit I'll definitely look into better routes to get to work. A 100 kms @ say $15 every fill-up over 7-8 months is a fair chunk of change $$$$.(more mods or track time)
culprit |ˈkəlprət; ˈkəlˌprit|
noun
a person who is responsible for a crime or other misdeed.
• the cause of a problem or defect : viruses could turn out to be the culprit.
If anyone interested this is exact route:
http://maps.google.com/maps/ms?hl=en...,1.560059&z=10
Yesterday on my drive to the sherway meet I filled up with Sunoco 91 I habitually use Shell V-Power 91, but it was on the way. Approximately a 120 km round trip with mix driving of side roads @ 70-110 km and highway @ 110-130 with bursts close to 149 km with no stops other than lights. For the first time in ages I got 120 km out of the first quarter tank, my normal lately is 70-85. I believe what is killing my fuel economy is the stop/start/idle I do on the 404 everyday I drive the car that route.
I'm still going to change out my/plugs/wires/coils in the spring but truly don't believe I'll see a significant increase in my fuel economy with ever growing traffic congestion in the GTA.
But you never know it could the change to Sunoco 91, but I doubt it. In short I generally don't pay that much attention to my mileage (you get what you get attitude) but if this is truly the culprit I'll definitely look into better routes to get to work. A 100 kms @ say $15 every fill-up over 7-8 months is a fair chunk of change $$$$.(more mods or track time)
culprit |ˈkəlprət; ˈkəlˌprit|
noun
a person who is responsible for a crime or other misdeed.
• the cause of a problem or defect : viruses could turn out to be the culprit.
If anyone interested this is exact route:
http://maps.google.com/maps/ms?hl=en...,1.560059&z=10
Last edited by RXeckless; 10-25-2009 at 08:50 AM. Reason: Route
10-25-2009, 05:02 PM
#44
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i'm pretty sure everyone knows this but you should easily be able to get your 8 over 450km a tank when traffic isnt a issue. i live in the country and drive every where at 100km/h also my shortest journey is rarely under 75km one way. a while ago i was getting some really nice numbers and i was unsure what was going on then i remembered i had doubled my premix to 8 from 4oz a tank.
10-25-2009, 05:34 PM
#45
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I just got 396 when red light came on yesterday after doing 3 downtown - uptown trips and then a round trip to and back from hamilton...the trips downtown go around 100-120 taking approx 10-15 min...coming back up varies...it usually takes me approx 20-30 min to get back up travelling anything between 40-70/80 km/h. Trip to hamilton there and back was around 100 kmh. So i'd say my driving is a 40/60 local/hwy mix...and I get approx 13.5l/100..
the best i've ever done was a round trip to and back from london..which gave me 12.2L/100 which is better than the EPA ratings :D
the best i've ever done was a round trip to and back from london..which gave me 12.2L/100 which is better than the EPA ratings :D
10-25-2009, 05:37 PM
#46
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and nate..wow your focus uses only 6.5L/100km...that's about how much our hybrid camry uses
one more thing, i find that the fuel gauge isn't very accurate anymore. I used to be able to do 100kms by the bottom of the first quarter...but no i'm only getting in 70-80, then about 150 by half way as opposed to 200 from before. But despite these changes, i'm still getting the same mileage from each tank :D about 320-360 depending on how i was driving.
one more thing, i find that the fuel gauge isn't very accurate anymore. I used to be able to do 100kms by the bottom of the first quarter...but no i'm only getting in 70-80, then about 150 by half way as opposed to 200 from before. But despite these changes, i'm still getting the same mileage from each tank :D about 320-360 depending on how i was driving.
10-26-2009, 05:55 AM
#47
i'm pretty sure everyone knows this but you should easily be able to get your 8 over 450km a tank when traffic isnt a issue. i live in the country and drive every where at 100km/h also my shortest journey is rarely under 75km one way. a while ago i was getting some really nice numbers and i was unsure what was going on then i remembered i had doubled my premix to 8 from 4oz a tank.
10-30-2009, 01:51 PM
#48
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Our gas light turns red?? I thought it was just yellow... 
How much gas/time do we have once it turns red?
Anyway I'm already at 400km and the light has not come on yet. But I do generally shift below 4000rpm except for the daily red line in second gear if I'm able.
How much gas/time do we have once it turns red?
Anyway I'm already at 400km and the light has not come on yet. But I do generally shift below 4000rpm except for the daily red line in second gear if I'm able.
10-31-2009, 09:17 AM
#50
UPDATE: Results are in!
My experiment is complete.
Paramaters:
- 1 tank of Shell V-Power
- 286 km on highway and 110 of city driving, translating to a 28/72 city/hwy driving style.
- No shifts above 5000 rpm, in fact most were performed at 4000 rpm
- Highway speed is kept at 101 km/h to 110 km/h, always in 6th gear
- City driving speed is posted limit + 10 km/h max, try to use 5th and 6th gear if condition allows.
Results:
396km before light comes on. I drive for an additional 32km to 428 km before I went to fill up. At the pump, I fill up 51.990 litres of fuel ~> 52L of fuel. The rx8 fuel tank is 60L. Extrapolating the potential mileage that could be obtained from the remaining 8L is approximately another 64km of distance until the car completely dies on the road. Total potential driving distance: 492km
Conclusion:
1) Nate340 is correct, the rx8 can do at least 450km on one tank
2) Driving style DOES SERIOUSLY affect mileage on this car. Before I thought it didn't, but I had not conducted a thorough investigation until now.
3) Recall my initial gas consumption driving aggressively/fun 100% of the time resulted in only 290 km until the light came on. This is a staggering 106 km difference in fuel consumption between the two driving styles
4) This driving style, though may appear slow on paper is actually more than sufficient to move around the city. I was still faster than most cars on the road, so you wouldn't have to worry about looking like a corolla.
5) My coils are perfectly fine, otherwise the result of this experiment would prove otherwise. A car with bad coils can't possibly get this mileage. I have nothing to worry about.
Paramaters:
- 1 tank of Shell V-Power
- 286 km on highway and 110 of city driving, translating to a 28/72 city/hwy driving style.
- No shifts above 5000 rpm, in fact most were performed at 4000 rpm
- Highway speed is kept at 101 km/h to 110 km/h, always in 6th gear
- City driving speed is posted limit + 10 km/h max, try to use 5th and 6th gear if condition allows.
Results:
396km before light comes on. I drive for an additional 32km to 428 km before I went to fill up. At the pump, I fill up 51.990 litres of fuel ~> 52L of fuel. The rx8 fuel tank is 60L. Extrapolating the potential mileage that could be obtained from the remaining 8L is approximately another 64km of distance until the car completely dies on the road. Total potential driving distance: 492km
Conclusion:
1) Nate340 is correct, the rx8 can do at least 450km on one tank
2) Driving style DOES SERIOUSLY affect mileage on this car. Before I thought it didn't, but I had not conducted a thorough investigation until now.
3) Recall my initial gas consumption driving aggressively/fun 100% of the time resulted in only 290 km until the light came on. This is a staggering 106 km difference in fuel consumption between the two driving styles
4) This driving style, though may appear slow on paper is actually more than sufficient to move around the city. I was still faster than most cars on the road, so you wouldn't have to worry about looking like a corolla.
5) My coils are perfectly fine, otherwise the result of this experiment would prove otherwise. A car with bad coils can't possibly get this mileage. I have nothing to worry about.