A rather thirsty March 1.0

[CMF_Bogchook]

Hi all. I found this site while doing googling about for an answer to a problem I'm having with a lovely little March 1.0 that I bought my wife a while back.

I have lately noticed that it is using what I think is way too much fuel for a car of this size. I've had my suspicions for some weeks but I was using it myself for the last few days and it took more than 13 litres to cover less than 150 kms (or a nudge over 30 mpg in the old language). My driving included about 70 kms of open road and the rest a mixture of urban running.

The car is a '98 March 1.0 litre auto, with just 22,000kms on the clock. I changed the air and fuel filters when I bought it, it has brand-new correctly inflated tyres (to replace the frankly awful factory Toyo Kogyos), it starts on the first turn of the crank, runs like clockwork, and performs faultlessly - with this one exception.

I've heard somebody mention that a faulty oxygen sensor can cause the fuel consumption to skyrocket but before I go down that path does anybody here have a suggestion?

Many thanks, and congratulations on a great site.

 

[CMF_Micra_King]

O2 sensor should been fine if the car has only 22,000km's on the clock but could still be faulty I guess. What type of auto do the march ones come with? CVT like the UK sourced micras or normal type? Also you might want to inspect the fuel lines to make sure there not leaking.

 

[CMF_Bogchook]

It's the normal four-speed auto. There are no fuel leaks - I've checked that one. I should also state for the record that my wife drives with a very light foot, and in my week of using the car I purposely drove it very gently.

 

[CMF_Micra_King]

If everything seems ok then it might be worth replacing the O2 sensor then. Also jack the car up and make sure the wheels spin without to much drag to rule out a bad bearing or brake cylinder.

 

[CMF_Bogchook]

Thanks Micra King. I know that the brakes aren't binding - I was pushing the little car down the driveway just yesterday to get it out of the way of something I was doing.

Is there a simple method of testing the 02 sensor to determine whether it is working correctly?

 

[CMF_frank2]

Bogchook WROTE:
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Is there a simple method of testing the 02 sensor to determine whether it is working correctly?

bogchook, if the middle (white) lambda wire is reading about .5v while your cruising, it,s working ok.
and a faulty coolant sensor might cause overfueling

frank

 

[CMF_Bogchook]

Hi Frank. Thanks for that, but I need to know two things. Where is the sensor located, and how do I test it while cruising? I recall reading somewhere that there was a voltage test you can do on them with the ignition on but the engine off.

The temperature gauge reads fine, so can I assume you're talking about a separate coolant sensor for the EM that causes overfueling?

Pardon my ignorance everybody, and please accept my gratitude for the answers so far.

 

[CMF_frank2]

bogchook

the lambda is bolted into the front of the exh manifold, you might be able to test it in neutral at, say 3000rpm ?, if not you,ll have to run a the wire to the cabin (+ an earth)
and yes, there,s a 2nd (bigger) coolant sensor under the dizzy

frank

 

[CMF_Bogchook]

Got that. I'll get the wife to prod the pedal tomorrow and measure that voltage. There's no rev counter (and my timing light doesn't have one built in) so I'll have to judge 3000rpm by sound.

How would I determine if the coolant sensor is faulty?

 

[CMF_frank2]

Bogchook WROTE:

<BR>
<BR>
How would I determine if the coolant sensor is faulty?

bogchook, my lambda voltage is off the scale rich (ie, over .9v at any throttle position or rpm) until the engine warms up, and then the voltage is roughly .5 at cruise, zero v on lift and most times it,s rich (.9v+) on acceleration.
so if yours is .9v+ when warm, i would think it,s overfueling for some reason

frank

 

[CMF_Bogchook]

Hi Frank, I've got a busy car day today trying to get the servo on my Rover P6B reassembled and working, but I will at some point attempt to check that lambda sensor. If it's crook I hope a replacement isn't too expensive... :-0

 

[CMF_frank2]

bogchook

aah, ye olde p6 (ally doors and bonnet were,nt they ?), i think any generic 3 wire ebay jobbie will do

frank

 

[CMF_Bogchook]

Ally bonnet and bootlid, but the doors are sturdy British steel. A fine car, and still a good drive.

I've recently given up my job with its handy perk of a company car, and in its absence I have de-retired the Rover. I don't yet feel hard done by. Petrol bill excepted of course.

 

[CMF_Bogchook]

Well gents, after weeks of working away from home and other distractions, I have finally got around to testing the lambda sensor on the family March. As you can see from the photo below it has only one wire, but it is white. After arriving home from a trip out I disconnected the plug and stuck my multimeter between the pin and the negative post on the battery while the wife sat in the driver's seat and maintained steady rpm. No matter what speed she held the engine at the meter read approximately 0.9 V, just fluctuating slightly.

Have I found the problem? I can confirm that while I've been away the car has been achieving stunning fuel consumption figures of about 10 km/l. I think my V8 doesn't do much worse than that.

Best regards to all on the forum.

 

[CMF_Bogchook]

The local agent has quoted me $89.99 (NZD) for a new sensor. I hope this works!

 

[CMF_Orleando]

Hi. I have similar problem mine micra eats about 8-9L/100km and it is way too much. Today Ive checked lamda sensor with voltmeter and dont know if it is really bad. This is what we did: warmed up engine, then tried to access the trouble codes but shortening the bottom left pins was useless, Ive tried few times but no light came on the dashboard, so then we decided to check it with voltmeter. When the engine is at steady rpm (about 2000-3000) it shows about 0 and not changing, when engine is left to work at idle the readings go up to about 0.8v but not fluctatng as Ive read it should be. So is my lambda sensor working?

 

[CMF_frank2]

bogchook
i cant see how it could work with only one wire, are there any cut wires there ?

orleando
my voltage is very random on tickover and acceleration, but it,s always fluctuating between .4v and .6v at cruise (ie, constant 30mph or 70mph etc) and always drops to zero on lift

frank

 

[CMF_Bogchook]

Hi Frank, thanks for getting back to me. In the following link there is some info about single-wire sensors:

http://www.topbuzz.co.uk/info/oxygen_sensor/oxygen_sensor.htm

I don't know if you can discern it in my picture above, but there are no cut wires. Also bear in mind that this is only a problem that has developed in recent times, and since 2007 nobody but me has ever had their head under the bonnet of "CHK259".

The local parts outfit I contacted confirmed that they had a single wire sensor for the March in stock. I presume that vehicle earth completes the necessary circuit.

Orleando, I'd be quite pleased with only using 8-9 litres/100kms. CHK259 has been gobbling through about 10!

Regards,
Warren

 

[CMF_Wilzy]

sorry to steal the post Bogchook..
but does anyone in the U.K know where i could get a new OS? or is it gonna be an internet jobby?
ive got the same problems as you bogchook hopefully i have the same issue with the oxy sensor too.
fingers crossed!!

 

[CMF_Bogchook]

No apology necessary Wilzy!

Here in NZ I'm able to get it from the local "Super Cheap Auto Spares" chain store. They are stockists of general automotive spares and accessories which leads me to think that the OS for the March is a fairly generic device. I imagine you'd find one at a similar store in the UK without too much trouble.

 

[CMF_frank2]

bogchook
you could try the test mode thingy

 

[CMF_frank2]

2nd pic

 

[CMF_Bogchook]

Hmmm, I think we might be up against the differences between an English-made Micra and a JDM March.

Here's what my fusebox/diagnostics plug looks like:

 

[CMF_frank2]

nah bogchook, it,s just yours is mounted upside down (southern hemisphere) lol

frank

 

[CMF_Bogchook]

Well here's the rub. I managed to set the ECU to diagnostic mode, so I took the car for a drive around the block to warm it through, put it back into diagnostic mode and started the engine. At good steady revs the engine light flashed regularly at me as if everything was OK.

What now?

 

[CMF_Bogchook]

frank2 WROTE:
"it,s just yours is mounted upside down (southern hemisphere) lol

Yes, very good Frank! I've just tested the voltage again with my son holding the accelerator and the voltage sat around 0.8 - 0.9 V as the revs varied slightly around the 2-3K mark (I'm going by sound as there is no tacho). There was a drop in voltage on lift-off.

 

[CMF_frank2]

bogchook
your sparkplug colour can give a good indication on a/f/r,s eh

frank

 

[CMF_frank2]

Bogchook WROTE:I've just tested the voltage again with my son holding the accelerator and the voltage sat around 0.8 - 0.9 V as the revs varied slightly around the 2-3K mark (I'm going by sound as there is no tacho). There was a drop in voltage on lift-off.<BR>
<BR>

bogchook
going by that then, i would say the coolant temp sensor is stuck on cold ?

frank

 

[CMF_Bogchook]

I guess it'd pay to check that, Frank. The temperature gauge reads OK, but there's a second coolant sensor for the ECU isn't there?

Below is a pic of the No.1 sparkplug, taken moments ago. I was struggling to get enough light to show the colours properly, but I think you can get the idea.

 

[CMF_frank2]

bogchook
looks a nice colour eh, and yeh, the single wire one is for the guage (next to the ecu one)
my fan kicked in when i joined the 2 sender wires, so i assume it,s hot engine = high resistance ?
edit, 300 ohms @ 80deg c
frank

 

[CMF_Bogchook]

I'll whip it out and see what the deal is.

 

[CMF_frank2]

bogchook
300 ohms @ 80deg c
and 3.3 ohms, lambda btw (edit, scrub that, thats the lambda heater value, which does,nt apply to yours)
frank

 

[CMF_Bogchook]

Thanks Frank. What a beast of a thing to get to! I haven't succeeded yet, but if I can just get the plug off then with the engine warm I should see the 80 ohms without having to pull out the sensor.

When should I see 3.3 ohms across the lambda sensor? Cold engine, warm engine, running, not running?

Warren

 

[CMF_frank2]

warren
sorry, i,ve edited the previous post, re, lambda

frank

 

[CMF_Bogchook]

Right, I've got the plug off. I'm just trying to manoeuvre my multimeter prongs down there now. What a bastard of a thing to get to.

 

[CMF_frank2]

warren

edit, yeh i know, you might end up pulling the dizzy out eh

 

[CMF_Bogchook]

That pic is well worth seeing. I just spun the car around the block to warm the engine through again and managed to get my multimeter prongs into the little plastic shroud and prod about until I got a reading. As I messed about the resistance started at about 340 ohms and over a minute or two climbed to approximately 350 ohms. This would tally with an engine that wasn't quite at full temp. I suspect from this that the coolant sensor is OK.

 

[CMF_Bogchook]

And for your information, here is a pic of the exhaust pipe. It seems a little dark to me, but my point of reference is a rather elderly but freshly tuned Rover V8 which runs a silvery-grey pipe.

 

[CMF_frank2]

warren
yeh, it seems ok eh, you could check the fuel consumption with the lambda disconnected, to see if it,s any worse than now, eh ?

frank

 

[CMF_Bogchook]

I'm a little flummoxed all told. ECU diagnostics suggest the lambda sensor is OK, spark plugs, exhaust and coolant sensor seem OK. But fuel consumption is horrendous for a 1.0 litre.

I still concerned that the lambda voltage is rather high (0.8 - 0.9V) at steady revs compared to the 0.5V that has been suggested. Could it be possible that the ECU thinks 0.8-0.9 is OK (hence the OK diagnostics) but it is actually a faulty sensor?

I'm in a quandary as to whether to gamble $90 on a new lambda sensor. From trawling around the net it seems like faulty lambda sensor/poor fuel consumption is a common problem with the Micra/March.

 

[CMF_Bogchook]

Here is some useful info on lambda sensors and how to check them:

http://www.picoauto.com/applications/lambda-sensor.html

Can anybody tell me how to locate the return fuel line?

 

[CMF_Bogchook]

I've just done a little more testing with the multimeter. An obliging wife on throttle duty maintaining a fully warmed engine at around 2-3000 rpm (going by sound) produced a lambda sensor voltage of approximately 0.9V.

Dropping the throttle off made the voltage briefly fall back to zero before resuming duty at 0.9V.

Holding the revs high and pulling the vacuum servo hose off (artificially creating a lean situation) caused the voltage to fall to zero and stay there.

Replacing the hose and holding the revs at a high value (unknown speed but too uncomfortable to keep my head under the bonnet without ear muffs) meant a randomly dancing voltage that leapt about from about 0.3 to 0.9, mostly sticking to higher values.

The meter is a Fluke 79, so it is not possible to get a true feel for what that dancing voltage is really doing, but maybe somebody can interpret it a little.

 

[CMF_frank2]

Bogchook WROTE:

Can anybody tell me how to locate the return fuel line?

warren, the return is connected to the pressure relief valve on the end of the fuelrail
and i dont think you will get a true closed loop reading unless you actually cruise the car (eg 30mph, 50mph)
maybe your oddball 4 speed box (were,nt most k11 auto,s cvt ?) has an unsuited diff ratio for a 1.0 ?

frank

 

[CMF_Bogchook]

Hi Frank,

There's nothing oddball about the 4-speed auto - nearly every JDM March in the country has one, and most NZ-new Micras too. The manuals are hard to find here, and the CVT is never seen. It might be the other way round and the CVT could be the rarer of the two when worldwide production is added up.

Remember also that this car used to sip fuel very frugally and I only noticed the consumption go silly over the last few months.

I'll run with your suggestion and do a drive test tomorrow with some wires fed back the cabin. Could be interesting. Hopefully more conclusive.

 

[CMF_frank2]

lol warren, i stand corrected,
mine is just a meter on the dash with 1 wire tapped into the lambda (t,other one earthed), i,m running on gas 99% of the time and i find it usefull

frank

 

[CMF_Bogchook]

Frank, perhaps if you place a southern hemisphere March auto in a container and ship it north of the equator (thereby inverting it), when you extract it at the other end it will have Micra badges and a CVT trannie.

I'll post again in the morning after I've had a chance to do a test drive and try the return line clamp test.

Cheers.

 

[CMF_tiSh]

my 1.3 consumes about 5km per liter. hope it makes u feel any better

planning to check the lambda/o2 sensor also...

or probably the ECU needs resoldering

 

[CMF_Bogchook]

My 10 kms per litre sounds positively frugal by comparison!

As you can see if you read the whole thread, my testing and experimenting has been somewhat inconclusive so far. I'm going to jury rig a couple of wires into the cabin this morning and drop my wife off at work, which should give me a good opportunity to see what the lambda voltage is doing under real-world driving conditions.

Watch this space.

 

[CMF_Bogchook]

OK Micra Fans, I've just rigged up my multimeter and will soon embark on a real-world test drive through city traffic to see what's happening with the lambda sensor.

Here's how the test rig looks under the bonnet:

 

[CMF_Bogchook]

And inside the car:

(The voltage shown on the meter is the lambda sensor at idle with a cold engine).