High fuel consumption

A

Abaaba

Hi

As the title says, My Micra's fuel consumption inst what it is meant to be. I am currently getting 200 miles for £33 (roughly about 30 itres), so far I have changed spark plugs, air & fuel filter - oil and oil filter was changed in August (according to previous owner) and checking at the oil, it looks newish.

I am thinking of checking lambda sensor but got few questions regarding this. Do I need special tool to take it out? does the k11 02 Micra have 2 lambda sensors or just 1? I ma gana clean it first and see if it makes any difference but what sort of cleaning products to use? Wat else should I be checking apart from lambda sensor?

Really appreciate your help/support
 
Last edited:
check tyre pressures,
ECU coolant temp sensor resistance within spec (reading too cold may force ECU to always run too rich),
thermostat is closed when below 82C (being stuck open will waste engine heat and make it run too rich),
if ur 1L has a distributor, clean the white oxide inside the dizzy cap that could weaken spark, then check the dizzy ignition timing is in sync with the crank pulley timing (need strobe),

check primary O2 sensor in manifold is responding fast enough to keep the mixture correct. can check by either plugging a laptop or ODB1 reader to the diagnostic port to access sensor readings or set the ecu into diagnostic mode via a "short two diagnostic port terminal pins with paperclip" trick and looking at the engine light for the flashing codes. at 3k rpm it should flick between rich/lean twice per sec.

can normally be removed off the manifold with a 22mm spanner but if it's seized you either need a special 22mm socket with a slot cut (of u wanna re-use the good sensor), or just cut the wire and use a long 22mm socket (if the sensor is gonna be replaced).

the secondary O2 sensor behind the Cat is just for emissions, checking if the cat is cleaning the gases.
 
Abaaba said:
Hi

As the title says, My Micra's fuel consumption inst what it is meant to be. I am currently getting 200 miles for £33 (roughly about 30 itres), so far I have changed spark plugs, air & fuel filter - oil and oil filter was changed in August (according to previous owner) and checking at the oil, it looks newish.

I am thinking of checking lambda sensor but got few questions regarding this. Do I need special tool to take it out? does the k11 02 Micra have 2 lambda sensors or just 1? I ma gana clean it first and see if it makes any difference but what sort of cleaning products to use? Wat else should I be checking apart from lambda sensor?

Really appreciate your help/support
Click to expand...
you can easily monitor your lambda readings etc on an obd2 car (£4 bluetooth scanner and smartphone) no point removing them if they are functioning ok,
what engine and driving conditions ?
 
If you have a 1ltr and doing it all around town, then that's about right.
If you're getting that extra urban, you're to heavy on the old right foot.
The 1.3/1.4s are better on fuel than the 1ltr.
 
davyboy said:
If you have a 1ltr and doing it all around town, then that's about right.
If you're getting that extra urban, you're to heavy on the old right foot.
The 1.3/1.4s are better on fuel than the 1ltr.
Click to expand...
I am only getting 30 MPG for 1L Micra and I am not heavy right footed either so there is gatta be something.
 
frank said:
you can easily monitor your lambda readings etc on an obd2 car (£4 bluetooth scanner and smartphone) no point removing them if they are functioning ok,
what engine and driving conditions ?
Click to expand...

Thanks fro that frank, I am a bit more to get a decent OBD2.
 
30 is,nt far out for urban driving in the winter tbh, all of my k11,s averaged about 70 miles/tenner
if you want good milage dont drive a petrol car basically, my morris 1000 pickup i drove in the early 70,s had the same mpg (progress eh)
 
also check ur alignment is straight and all 4 brakes not dragging.

winter is alot more uneconomical (longer time spent warming engine up with cold rich mixtures, longer use of lights as daytime shortens, longer use of demister, longer time wasted waiting for frozen car to thaw whilst idling with 0mpg)

normally a stock k11 should be doing round 50+mpg motorway and 35-45mpg urban so something odd is really dragging/wasting the cars fuel at 30mpg unless you've spent all day stuck in traffic and red-lining everywhere
 
Owned two 1 litre K11's and they are not particularly ecomonical cars. The engine is very robust, but still technologically an old design.
The missus runs a 2006 1 litre Toyota Aygo, and she achieves many more MPG's than me. I'm jealous :D
 
frank said:
30 is,nt far out for urban driving in the winter tbh, all of my k11,s averaged about 70 miles/tenner
if you want good milage dont drive a petrol car basically, my morris 1000 pickup i drove in the early 70,s had the same mpg (progress eh)
Click to expand...
Ha ha Frank, I had a Morris 1000 as well, remember the pop, pop, pop when decelerating with fond memories.
You could tell one coming well before you saw it.....LOL
 
This is off the topic but does anyone know what is meant to connect on this connection?

x2tic6.jpg


was replacing driver door actuator and noticed this connector which had nothing connected to it and was wondering what it is for really.
 
pollyp said:
check primary O2 sensor in manifold is responding fast enough to keep the mixture correct.
Click to expand...

does this come off from the TB or is it soldered to it? I wanted to clean it today so when i removed the 2 5star screws and tried to remove it, it wouldn't come out i mean it would wiggle but I didn't want to use brute force to remove it in case I break something.
 
Abaaba said:
does this come off from the TB or is it soldered to it? I wanted to clean it today so when i removed the 2 5star screws and tried to remove it, it wouldn't come out i mean it would wiggle but I didn't want to use brute force to remove it in case I break something.
Click to expand...

are u talking bout the IACV on the TB or the O2 sensor on the exhaust manifold?

the IACV normally has a o-ring seal which you just wiggle/twist/pull gently to pop out. anyone got a pic of the facelift IACV how it comes off?
on refitting, u put smear of wd40 on the oring, gently push & twist it back in.

the primary O2 is on the manifold above the first cat, removed with 22mm spanner
 
someone with facelift can answer that. alternative without removing the MAF module is to spray carb/brake cleaner through the MAF wire to flush dirt off whilst holding throttle plate wide open, let fully dry before use
 
frank said:
you can easily monitor your lambda readings etc on an obd2 car (£4 bluetooth scanner and smartphone) no point removing them if they are functioning ok,
what engine and driving conditions ?
Click to expand...
Is it possible to monitor lambda readings on a 1.0L pre-facelift k11 98'? I'm starting to think my micra is eating a bit too much. It would be awesome to see what's happening with the mixture and figure out how to improve my mpg.
 
Arturio said:
Is it possible to monitor lambda readings on a 1.0L pre-facelift k11 98'? I'm starting to think my micra is eating a bit too much. It would be awesome to see what's happening with the mixture and figure out how to improve my mpg.
Click to expand...

All micras have a narrow band O2 sensor feedback to the ecu, so with a diagnostic cable & software or hardware u can see what the ecu see's.

The O2 sensor only detects if the mix is too rich or too lean, so it should flick up down rapidly. Only an expensive wideband will give accurate wide range of mixture readings for tuning.
 
What would be the necessary software for ecu readings if i find a diagnostics cable? And how does one see if the O2 sensor is flicking, through ECU?
 
Arturio said:
What would be the necessary software for ecu readings if i find a diagnostics cable? And how does one see if the O2 sensor is flicking, through ECU?
Click to expand...
.1v is lean and .9v is rich arturio, so if its bouncing around .45v one or two times a second then its closed looping fine
 
If the narrowband seems to move sluggish or hangs more towards rich or lean then either the sensors old or other parts of the engine is making it run offset ie vac leak, Duff coolant sensor, faulty maf etc. The mixture air/fuel learning alpha would indicate how far off the mix are.
 
UPDATE......

I have changed fuel filter (I don't think it was ever changed) spark plugs and air filter, cleaned the MAF sensor and made sure tyre pressure was spot on, now I am getting 38 mpg.
 
Abaaba said:
UPDATE......

I have changed fuel filter (I don't think it was ever changed) spark plugs and air filter, cleaned the MAF sensor and made sure tyre pressure was spot on, now I am getting 38 mpg.
Click to expand...
That's spot on Abaaba, nothing better than spring cleaning the maintenance of your motor.
What you have done, I do every year, makes for trouble free motoring.
 
When my gf uses the 1.0 k11 she does 220miles with a tank. It's only 4miles to her work.
When I went to the uk with the Micra, 2 big guys + car full of camping gear I did 370miles with a tank.
So, keep the tires on pressure, ensure your maintenance is good (good oil is important), don't do short distances and use the throttle 50%, you don't go much faster when it's 100% but you use a lot more fuel.
 
Kefke said:
When my gf uses the 1.0 k11 she does 220miles with a tank. It's only 4miles to her work.
When I went to the uk with the Micra, 2 big guys + car full of camping gear I did 370miles with a tank.
So, keep the tires on pressure, ensure your maintenance is good (good oil is important), don't do short distances and use the throttle 50%, you don't go much faster when it's 100% but you use a lot more fuel.
Click to expand...
Nice one Kefke. I did a small test on mine the other day (1.4) I got 374 miles on tank just around town !!!!! driving just like that.
 
My 1l gives me a strong 42 mpg so long as I don't press it too hard, that's after giving it an oil change and changing the fuel filter, fuel was literally black coming out of filter, really grimey before it gave me around 32mpg
 
Kefke said:
No, it was not around town. It was a trip from Belgium to the UK and back.
But the car was heavy loaded and a lot of traffic jam...
Click to expand...
Thats perfect ! is very good fuel consumption
Am thinking to change the coolant sensor. because the car keeps high revs for at least 5 min after the first start when the engine cold
Maybe is too rich the mixture for a long time ? what do you think ?
 
George k11 said:
Thats perfect ! is very good fuel consumption
Am thinking to change the coolant sensor. because the car keeps high revs for at least 5 min after the first start when the engine cold
Maybe is too rich the mixture for a long time ? what do you think ?
Click to expand...

You can check the coolant sensor ofcourse. De-mount it and you can measure the resistance with your multimeter.
I think you find some info about it on this forum. If not, I can send you the values from the workplace manual.

What also can me a solution is to remove the waxostat. The idle is adjusted by 2 things: Idle valve and a waxostat.
the first one is controlled by the ECU, the second one by a wax (temperature)
you can remove the waxostat. I did that too, the only difference I noticed is that if you release the throttle, the throttle stays on for 2-3s.
But I was to lazy to but it back lol.

The Micra (and all other gasoline cars) use a LOT more fuel when they are cold. So, you can do what you want, if you only drive it when the water is colder then 80°c (meter = 50%) it will consume a lot more .
 
the 1300rpm'ish fast idle for the initial 5min cold start below 82C is normal, heats up engine asap.

also check for thermostat stuck open which makes it harder / longer to heat up so it burns more rich fuel.

indicated temp and ECU sensor temp are 2 separate systems, so remove and test the 2-pin ECU temp sensors resistance-per-degreeC
https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-119#post-704079

the old waxstat mechanism behind the pre-facelift TB often seize & keeps the throttle stuck open. follow the guide to remove the mechanism & reset idle
https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-19#post-446256

and when the engines warm & car's stationary & rpm was above 1000rpm, it's normal for the idle to spend 2-3s at 1000rpm (IACV kept open to prevent stalling) before the ECU shuts the IACV and return idle down to 750rpm
 
frank said:
i always ran with 2 coolant temp sensors to cut down on the coldstart enrichment, wired in parallel
Click to expand...
Hello Frank.
I get that mpg these days by driving like you suggested many moons ago.
Don't know if you remember, pulse and glide you said. Works well.
I was trying the engine off and coasting at the time and got up to 71 mpg, but you cannot drive like that in everyday driving.
Pulse and drive you can. So I've been doing that ever since, so a belated thanks for that.:D
I still have my 18 year old moments, but not many these days, starting to feel mortal now buddy, almost counting the days down now LOL
 
Dear friends

During the startup and some minutes after the the car smells like gasoline ! is a weird smell and am sure is not normal

I will check and do my test as you suggested hoping to find the solution !

Thanks
 
wehey said:
I'm intrigued........care to enlighten me :)
Click to expand...
Accelerate gently-ish, then where you can, out of gear and glide until you need the engine to drive the car again.
Accelerate again, and out of gear again, particularly useful when going down hill, but works well on the flat as well.
 
some pages about hyper-miling
https://en.wikipedia.org/wiki/Energy-efficient_driving
http://www.metrompg.com/posts/pulse-and-glide.htm

it's a long debate with huge amount of variable factors that affect results.
although useful in returning some mpg on a normal non-hybrid like our micras during empty motorway cruises, there are afew disadvantages too:
increased wear of clutch, IGN switch & gearbox,
really annoyed drivers behind you,
more driver effort & concentration & hassle required in coordinating pulse & glide, especially long journeys,
reduced safety if engine was stopped cos PAS, brake servo & ABS are dependant on it (could even be illegal in some states).

I once tried pulse & glide.
gliding in-gear with closed throttle,
or gliding in-gear with WOT and IGN off,
or gliding out-gear engine idling,
or gliding out-gear engine off,
tbh it only gave marginal mpg improvement of afew pence but wasn't worth all the hassle in a micra.

also found that fitting a turbo further complicates the engines optimum range where the turbo adds just enough boost for the best volumetric efficiency, while injection is still kept closed loop for max BSFC efficiency, and yet create enough power to overcome aero/mech friction.

my original stock NA micra used to favour cruising non-stop at slow 50mph with minimum weight giving 45-55mpg.
with my turbo, going slow & light gave the worst 35-40mpg perhaps cos the turbo wasn't being pushed enough to gave any beneficial returns.
on the other hand if my turbo was cruising at high speed 70-80 and fully loaded (ie my past roadtrip along the german autobahn), the turbo was boosting most the time in its sweet spot in closed-loop giving best power vs drag and resulted in 40-50mpg.
 
Interesting pollyp, I tried the engine off, and coast method, gave good returns, but you could never drive safely using that method in normal driving.
On the other hand, reasonable acceleration, out of gear with engine idling gives me a good return. Whether it is worth it with the frugal micra, maybe??
However at this time its become a way of driving for me now, and certainly can be used for everyday driving.
 
George k11 said:
Dear friends

During the startup and some minutes after the the car smells like gasoline ! is a weird smell and am sure is not normal

I will check and do my test as you suggested hoping to find the solution !

Thanks
Click to expand...
Hello George,
I have the some problem. I can feel the gasoline outside and inside the car when its running at one place. The usage is very high,11-13L/100km.

I change the Thermostat but its not working.

Did tou solved the problem ?
 

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