Tricky starting, mental revs and cutting out

#1
Hey hey,
So far you guys have been terrific help with the problems I've had, and I really hope you can help me out this time too:
I have a 2007 K12 Spirita 1.2 (80hp) that's developed a persistent issue.
First, it would cut out whilst driving, usually when revs were high (over 4000rpm). If I switched the ignition off and counted to 10 it'd start up again and run fine. Engine codes said cam sensor was to blame, and all signs pointed to needing a new timing belt. But when I took it to a talented and trustworthy mechanic he said the gap on the pulley/spindle was well within tolerances and solved the issue by swapping the sensor and cleaning the throttle bodies.
A few months later and it's cutting out again, and has also become super reluctant to start - it'll catch, then the revs will die and it cuts out. Try starting it again straight away and it'll turn over but won't start. Turn the ignition off and wait 10 seconds and it'll catch and start...then the revs will die and it'll cut out again. The only way of starting is to put the boot in on the accelerator before the revs die and hold the revs at 3000rpm for a few seconds, then it'll tick over.
However, the revs are lumpier than school custard and move erratically between 1000 - 2000rpm.
On my 2nd tank of fuel cleaner/petrol, so don't think it's dirty fuel lines. Thought it might be an air sensor, but now wondering if it might be the throttle position sensor?
All help gratefully received!
Thanks,
Sith
 
#2
Have you tried to plug a code reader into the OBDII port? Was invaluable when I was tracing a similar fault on my Saab......(that turned out to be a new throttle body was needed, no amount of cleaning solved the problem for more than a few days at best, though that isn't necessarily your problem)
 
#3
Hey John,
Yeah from memory the codes were P011 and P034 (or P032...might have them a little wrong, but it said the problem was the cam position sensors).
When I did my homework it said the likeliest cause was a knackered belt but my mechanic said it was fine.
 
#6
He checked it, said the tension was fine and gap was well within tolerance. This is why I'm confuseled!
Your 'mechanic' is an arse! The K12 does NOT have a cambelt it has a timing chain, and on the earlier K12 they stretch, putting the timing out giving exactly the problem you have. You need a new timing chain and tensioner kit fitted to solve it.:mad:
 
#8
Um...on reflection, I'm pretty sure he said "chain" when we discussed the possibility of it needing replacing.
When I wrote "belt" earlier, that was my mistake, not his.

Also, on start-up it runs lumpy. It's not misfiring, just a rough idle which settles down once it warms up.
I've noticed my offside sidelight flickering, which is unusual for an led bulb.
...Right?
Probably not related, but by this point I'll grasp at *any* straw...
 
#9
dodgy tail lights can cause problems on k12,s, the ecu assumes that you dont need a drive-by-wire throttle response when the brakelights are on for instance, so kicks it into limp mode for safety reasons
 
#12
So I changed the cam sensor today and now it starts first time every time.
WOOHOO!!!! 😁😁😁
Thanks god it wasn't the chain and pulleys - I'd have had to scrap the poor wee thing!
Good news. :cool: Just realised that it is a 2007 car, Nissan pretty much sorted the chain stretch problem sometime in 2004 when they fitted an uprated chain to all later K12's so the cam sensor change should sort the problem permanently. :)
 
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