Idle Issues and Fuel Economy

CMF_33driver

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Hey everyone,

Been driving my Micra LX now for almost a week now, very happy with it except for two things, which may be related.

First of all, every now and then the idle drops off to almost stalling levels (engine lights flicker on briefly) I've heard mention of the idle control valve and maybe the air flow sensor being the problem, however can't find any relevant info on actually how to check this for problems?

Second is fuel economy, still on my first tank, it's down to just under a quarter of the tank left, however I've only done just under 300k's. Thought i'd get a bit more than that? Common problems to look into? Car has been well looked after, however it has done 286 000 k's, so things may have been missed. I'm thinking common things like air filter, fuel filter? haven't had a chance to do a service on it yet. What sort of viscoisty oils do you guys run?

Cheers, Matt

Info on car:

1995/96 Micra LX, manual, 286 000k's on the clock, everything is stock.
 

CMF_littlebear

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Hey Matt, you should expect anywhere between 6 and 7 litres per 100km for daily usage - depending on driving situation, ave speed etc, and how heavy your boots are! I have had 3 Micra's in differing service condition/mods and a mix of peak traffic / open driving they all got (get) pretty much 6-6.5 litres per 100km.

I drove back to Adelaide from Brisbane a few months ago - At 80-90km I got nearly as low as 5L/100km, 90-110 got around 6 then hoofing along between 120 and 140 up to 7 L/100km.

Remember the tank capacity is only small. You should get another 70 or 80 klicks when the fuel light comes on.

Cheers,

Matt.
 

CMF_33driver

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hmm, well based on a guesstimate of 400km which is roughly what i'm guessing i'll get (just went under a quarter and am on 300km atm. That would mean i'm geting around 9.5L/100km based on around a 42L tank which seems high?
 

CMF_littlebear

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Go to the Servo and completely fill and re-set the trip meter. Drive for say 300km under your normal routine then go back and re-fill. Record how many litres it takes and work it out accurately that way. If you are still around 9.5 I reckon you start looking into it more. :)
 

CMF_33driver

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ok well it just put half a tank in on the way home, the fuel light came on at exactly 350k's so thats roughly 8.3L\100km. Am i working this out right? 350km divide by the 42 liters?
 

CMF_modular

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I usually fill up 50Km after the light has come on, which works out to be 34 liters to the top. Sure the tank is 42 liters but it rather drive the the servo than walk. Call me strange.

I always get over 400Km, sometimes 430Km.

This works out to be above 8L/100Km.

As I live in the inner suburbs of Melbourne I am always stopping and starting from one set of traffic lights to the next, pretty. I also give the car a hustle along at least once a day, again, not the best for economy.

This is much higher than the official manufacturers figures of 6L/100 in the city. Then again, 8L/100Km as a minimum economy isn't exactly expensive either so I can't really complain.

Any wisdom on how to improve the economy or thing to look for? Apart from wearing lighter shoes of course ;)

 

CMF_33driver

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yeah its interesting, i picked the car up when i bought it and took to straight to the servo as the fuel light came on about 10k's after picking it up. Filled it up and it put 44l in according to the bowser lol.

No doubt i drive the car with a bit of a heavey foot, but I'm going to do the resolder job on the air flow sensor and have a play with the idle control to see if ican get my idle problem to go away. this might intern help with the enconmy.
 

CMF_33driver

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maybe but i'm in brisbane hehe. I think it could be the idle control as well, the engine temps seem to fluctuate a fair bit, indicating the idle up isn't switching over or is switching intermittenly?

will look into both on the weekend and report back. Actually, anyone got some pics on where the idle control is? yet to find a haynes :)
 

smidge

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take the idle motor out and give it a clean with some carby cleaner or contact cleaner that doesn't eat rubber and plastic, a toothbrush is good for scrubbing out the black crap and gummed up stuff on it... put it back in and set the idle like yom described somewhere here..

 

CMF_qwerty132

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Hey all,

My micra slx also seems to use a lot of fuel.. Mine seems to idle fine though. Only the occaisonal hiccup on acceleration. Ill resolder it someday..

If I drive normally, I usually get about the same as you. Maybe a little worse depending on how i drive. I have done the paperclip thing and there is no errors being flashed from the ecu. I have had a full service(air, fuel, oil, plugs and oil) and it still seems to be the same. Im wondering if maybe my drums are binding a bit. When we changed the shoes, the drums where pretty hard to get back on but they seem fine now.

On the highway its a lot better. I can get 400-430 off just over 3/4 of a tank. I think it was 400 off like 28 litres

My micra has air con and power steering so I just assumed that the caused it to use a bit more. Being in Brisbane in summer, I use the air con nearly all the time(except when overtaking lol)

Id be interested to see if resoldering makes a difference in this situation.

Thanks
qwerty132
 

CMF_33driver

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hey guys,

Well I've resoldered the joints in the mass airflow sensor, took it out for a quick spin (not too long as the silicon was still drying). Noticed an immediate response in acceleration and overall power. HOWEVER, the air filter was clogged pretty bad and so was the front mesh on the mass airflow sensor. I cleaned these out (will get a new filter during the week) so that might have something to do with it. Idle seemed normal and no missing. Time will tell when i take it to work tomorrow so I will report back on that as I progress.

I'm going to clean the idle control valve and HOPEFULLY give it a service next weekend.
 

CMF_nz_aj

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You mention variations in the temperature. You probably need to replace the thermostat, should be about $15-$20. Use sealant to stick the thermostat into the housing & wait fro it to go off, before fitting the cover. If the thermostat slips down while you reassemble, it's very easy to tighten the lower bolt & break the cast cover. (Assuming the UK motor has the same thermostat arrangement as Japanese)

With 286,000km & a dirty filter & mesh the idle control valve is bound to be full of black gunk. Clean it all out & it'll be good.
 

CMF_ULL-00Z

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The micra seems to have a few problems with idle and fuel economy. As a few people have said here they are on the right track. On 2 micras i have worked on latley i found this problem,

Replace pcv valve and the vac line going to it. The pcv in a micra is 2 peices that are joined in the factory i've noticed that what ever adhesive that nissan were using goes pooress after the years of hot cold hot cold and they get frail. Vacume play a major role in the micras tune and fuel.

Hope this helps out for ya.
 

CMF_qwerty132

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maat WROTE:

"what you need is one of the complete units im selling atm :)

they both work 100% perfect
Click to expand...

So these ones that your selling in the other thread come with a good pcv valve and vacuum line as well?? :)

How much to post to 4120 in brisbane?

Thanks
qwerty132
 

CMF_33driver

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hey guys,

thought i'd drop in and give an update. Micra hasn't stalled or stumbled once since i resoldered the air flow sensor, so thats definately helped! Economy is still not fantastic, I've done all the measurements and am getting 9.8L\100Km.

I've replaced the air filter which was sh*thouse to say the least, just put in injector cleaner to see if that helps a bit. I'll do a full service on it this weekend to see how we go.

I'm yet to clean the idle up valve, but I figure since my idle is now solid and the car isn't stumbling thats an unlikely culprite for economy woes?

cheers,
Matt
 

CMF_1300cc

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Im not sure whats the fuel tank capacity but asuming its 36ltts u r fuel consump is @8l/100, which is fine if u r reving it hard. My micra used to do 12l/100k, things i have corrected are: water thermostat, idle valve oring gasket, and spark plug, now im getting ave 6.5-7.5l/100k
 

CMF_frank2

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1300cc WROTE:

"So you,re doing nearly 10l/100ks....and i also put some snake oil

M so far throttle response hav improve, ill b changing the sprk plug leads looks like still the orig nissan.
Click to expand...

bloody good stuff, that snake oil :D
just check that its closed looping at cruise low, then its just down to the power sapping tyres or your right foot
 

CMF_climberjoel

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LowMicra WROTE:

"1300cc WROTE:

"Im not sure whats the fuel tank capacity but asuming its 36ltts u r fuel consump is @8l/100, which is fine if u r reving it hard. My micra used to do 12l/100k, things i have corrected are: water thermostat, idle valve oring gasket, and spark plug, now im getting ave 6.5-7.5l/100k"</div>

It's a 42 lyr tank according to the Haynes manual, Im not revving hard gear change about 3k, so you changed the thermostat, and idle valve oring? I've got new spark plugs anyways
Click to expand...

sorry you probably realise this but your cacluations will be out as surely you are not going to bone dry in the tank before refilling. reserve light comes on with 5 liters to spare iirc. top it up to full, reset your ODO, drive for a bit (or a lot), top it up again and use that final top up amount and your kms.

also low didnt you say your spedo is reading funny? therefore your odo will be out too...
 
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