Micra starting problem

[Corbalicious]

Hi all, This is CG engine'd I know but thought you may be able to help.

My K11 1 litre micra has a problem starting after being left for a couple of hours at a time. To get it to catch I need to hold the ignition over and feather the accelerator, then keep gradually applying pressure to the accelerator to stop the revs from dropping, then it'll misfire or backfire (or both) a few times, then the revs will pick up and it'll run ok from there. Is it possibly a fueling problem? I think the fuel filter is in need of a change anyway but wondered if it could be something else.

All help appreciated, thanks.

 

[Dale]

Yeah, it could be a fuelling problem corbs,

It could be the fuel filter..or the injectors may be a bit gunked up, or it could be a problem with the idle air bypass.
Maybe try cleaning the TB out or running some Redex through the fuel system..

 

[Corbalicious]

Thanks dale, do I need to take the TB off to clean it out? It's a similar design to the GA engine, right at the back. Will try the easy stuff first.
What does the idle air bypass do?

 

[Dale]

It allows air to bypass the throttle plate at idle when the throttle plate is closed.
If no air was getting through to the engine via the bypass or throttle plate it would cause the vehicle to cut out.
From what ive seen on my TB, its just a small hole inside the TB Bore right where the throttle plate sits on the bore surface which redirects the air through the housing. On some cars its just a smalle hole actually on the throttle plate, or a stepper motor that opens the throttle plate slightly automatically..

Ideally 'IF' this is the cause of the problem, you would need to remove the TB and thouroughly clean it out..i suppose you might get away with it being still on the car, but it wont really get rid of the dirt/gunk, it will just move it somewhere else.

My 1.6 intake manifold im working on had lots of oily residue inside it..this is due to the cam cover breather pipe that goes into the induction kit causing oil to blow through into the intake system.

Like you said corbs, try the easy stuff first, try a fuel system addative and replacement fuel filter first..if it doesnt work you may have to take the TB off and give it a good clean. Hope this helps..