03 Micra K12 - Cranking but won't start when Engine Cold

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Thu 7 Jan 2021 16:51
03 Micra K12 - Cranking but won't start when Engine Cold - Garp242

First post on the site, although i've often used it for the great info. So, Hello to all ...

My K12 Micra has developed a Cold Start Problem that has me stumped !! Over Xmas, I noticed it was struggling to start first thing in the morning ... but would start eventually and run fine. But about a week ago, it just refused to start. Thinking it was probably the Engine Temp Sensor, I replaced that - but it has made no difference. Still no start when cold.

I've gotten around this a couple of times by removing the Spark Plugs, heating them with a blow torch and quickly putting everything together again. It then Starts no problem & runs great. No problem with starting or running when the engine is warm ...

Also, there are No DTC's coming up on code reader ...

Can anyone point me in the right direction ??

Thanks in advance.

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Thu 7 Jan 2021 17:56
03 Micra K12 - Cranking but won't start when Engine Cold - skidpan

I've gotten around this a couple of times by removing the Spark Plugs, heating them with a blow torch and quickly putting everything together again.

You're a better man than me, doing the plugs on a Micra is a nightmare. By the time its back together it will be stone cold. I would think it took me a couple of hours. Never again.

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Thu 7 Jan 2021 18:19
03 Micra K12 - Cranking but won't start when Engine Cold - elekie&a/c doctor
Firstly , is the battery in good condition? Does the engine spin over at a good speed? Are you able to read actual value of the temp sensor with your scan tool? These engines also suffer with stretched timing chain that can cause poor starting.
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Thu 7 Jan 2021 19:57
03 Micra K12 - Cranking but won't start when Engine Cold - Garp242

Battery is good - I recharged it overnight while I was waiting on the new Temp Sensor .So engine turns over as normal - but just wont fire. Can't read the value in situ - but I replaced the old Temp Sensor with New. Still the same problem. Thing is - when I heat the plugs and get it started - it runs perfect and will then start first turn - as long as the engine in warm ??

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Thu 7 Jan 2021 20:15
03 Micra K12 - Cranking but won't start when Engine Cold - elekie&a/c doctor
Have you thought about renewing the spark plugs . ?
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Thu 7 Jan 2021 20:40
03 Micra K12 - Cranking but won't start when Engine Cold - Garp242
Have you thought about renewing the spark plugs . ?

Not ruling it out - but would New plugs make any difference ?? They seem to work OK when I actually get the engine running. What would make them fail when the engine is cold ?? Just asking ... Would they not fail at all temperatures ??

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Thu 7 Jan 2021 21:44
03 Micra K12 - Cranking but won't start when Engine Cold - elekie&a/c doctor
There could be excess build up of carbon deposits on the top of the ceramic insulator . For what they cost , I would replace them .
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Thu 7 Jan 2021 22:47
03 Micra K12 - Cranking but won't start when Engine Cold - Garp242
There could be excess build up of carbon deposits on the top of the ceramic insulator . For what they cost , I would replace them .

Yeah, see what you mean. Worth a shot ....

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Fri 8 Jan 2021 14:20
03 Micra K12 - Cranking but won't start when Engine Cold - Garp242

I've gotten around this a couple of times by removing the Spark Plugs, heating them with a blow torch and quickly putting everything together again.

You're a better man than me, doing the plugs on a Micra is a nightmare. By the time its back together it will be stone cold. I would think it took me a couple of hours. Never again.

Yeah, you're right, it's a bit of a job all right ...But I since got a suggestion to spray petrol on the Air Filter and that works !! As I said, once the Engine is up to working temperature, car runs fine and no trouble starting - until it gets cold again (next morning). So it's a temporary fix until I can figure out what's causing the Cold Start problem.

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Fri 8 Jan 2021 20:09
03 Micra K12 - Cranking but won't start when Engine Cold - Dorset123

These engines can suffer from the Cam Chain stretching you need to get this checked.

This happens when oil changes have been missed if it has had oil changes every year or 12000 miles it should be fine but if the oil was changed at 15 month or 15000 miles etc that is what the problem will be.

The Cam Chain needs a "Cam Chain Protrusion check" if is outside spec this will be the problem.

Hope that helps

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Fri 8 Jan 2021 21:16
03 Micra K12 - Cranking but won't start when Engine Cold - Garp242

Thanks for the info ... Seen something about it on one of the Forums. I'll look into that.

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Wed 13 Jan 2021 13:02
03 Micra K12 - Cranking but won't start when Engine Cold - Garp242

Update :

I've ruled out the Cam Chain as a possible problem.

Since the sub-zero overnight temperatures disappeared, about 4 days ago, the car has started every morning without a problem ... and runs as normal.

The issue seems to be a "fuel enrichment problem" when engine is very cold . Already replaced the "coolant temp sensor" which made no difference.

I'm told that the engine should cut out when the MAP sensor is disconnected - Mine keeps running, so gonna replace that & see if it makes a difference.

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Thu 7 Jan 2021 18:35
03 Micra K12 - Cranking but won't start when Engine Cold - Engineer Andy

My old K11 Micra had the problem with the engine temp sensor (its reported in HJ's Good & Bad for that car, if the section still exists [might be too old and was archived]) and it was replaced by Nissan at their expense, even though it was out of warranty.

The trick was that after the original unit failed each time, repeatedly trying to start the car flooded the engine, so the RAC man told me just to temporarily remove the fuel pump fuse (I think) and crank the engine for a few seconds, allowing the excess fuel to be drained off.

Then it fires up ok once the fuse is put back. Just be careful you don't drain the battery doing so, especially at this time of year.

This might work on you car, but only if the first problem was the sensor and it lead to the engine being flooded. Not sure what it could be otherwise. I must admit my K11 (1Litre 16V engine) was never the best at starting in cold/damp conditions, and absolutely hated starting soon after a cold start to swap cars out of the driveway.

Whether such issues carried over to the K12, I'm not sure. Best of luck to the OP in finding a solution.

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Thu 7 Jan 2021 19:00
03 Micra K12 - Cranking but won't start when Engine Cold - elekie&a/c doctor
I remember the K11 cold start problems very well . Nissan issued a service bulletin whereby a resistor needed to be added to the coolant temp circuit , to trick the engine control system into thinking that the engine temp was actually warmer than it really was . This would prevent cold start flooding . However, doesn’t apply to the K12 models .
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Sat 9 Jan 2021 20:15
03 Micra K12 - Cranking but won't start when Engine Cold - blindspot

maf. just before air intake to carb. clean with contact leaner or carb cleaner . or swap

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Sun 10 Jan 2021 10:15
03 Micra K12 - Cranking but won't start when Engine Cold - skidpan

But I since got a suggestion to spray petrol on the Air Filter and that works !!

2 things.

That sounds a bit risky to me but its your car and life. Keep a few extinguishers handy and a mobile.

That will not be heating the spark plugs but will be richening the mixture, a bit like easy start did back in the days of Noah. So if it will only start after richening the mixture in this way it suggests that there is a sensor issue that is providing the wrong reading and no start up enrichment. Logic suggests the water temp sensor is the place to start. No idea about senors on Micra's, never needed to investigate ours but on early Ford Zetecs (up to about 1998) there were 2 water temp sensors, both in the stat housing. One only provided a signal to the temp gauge and the other a signal to the ECU. On later cars there was only one sensor (in the head) which proved a signal to the ECU. The ECU then sent the signal to the temp gauge, fan etc.

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Sun 10 Jan 2021 12:59
03 Micra K12 - Cranking but won't start when Engine Cold - Garp242

Hi There ... Thanks for the reply.

I agree with you about the "spraying petrol into Air Filter" fix ... It's not something I'm comfortable with !!

I also think it is down to a faulty sensor that is sending incorrect or NO signal to ECU. I've replaced the Coolant Temp Sensor but that made No difference. I THINK there is only one on the K12 - maybe someone on the Forum can confirm that ??

I now suspect the MAF Sensor ( the one on top of the Air Box, 4 terminals & 1 bolt ) may be faulty. If I disconnect it with the engine running - the engine continues to run. I'm informed that the engine should cut out when this is disconnected ?? Again, maybe someone can confirm or dispute that.

I'm also pretty sure that it's a "cold start enrichment" issue - but what's causing it , I'm not so sure of !!

As I said before, at ALL other times it runs & starts perfectly !!

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Tue 12 Jan 2021 09:13
03 Micra K12 - Cranking but won't start when Engine Cold - mickyh7

K11 problems were down to Dry Solder Joints on the Throttle Body.

A simple but fiddly fix. Or a new one at £400-£500 from Nissan.

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Tue 12 Jan 2021 11:53
03 Micra K12 - Cranking but won't start when Engine Cold - Garp242

K11 problems were down to Dry Solder Joints on the Throttle Body.

A simple but fiddly fix. Or a new one at £400-£500 from Nissan.

Read some posts about that, but I don't think it applies to K12 models.

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