vn missfire on start

[fisher]

vn s will misfire at startup after a few days stationary .Motor will miss for a few seconds then run fine for rest of day .What is causing it. I have replaced coils fuel pump and ignition module and thought it was fixed but it has returned has someone had a similar problem.

[Morton]

Sounds like something's leaking into the combustion chambers.

I'd check the inlet manifold gasket for faults, which could be causing coolant to seep into a chamber overnight.

[greenfoam]

leaky injector/s do this, Unlikely for coolant to get into a port from a leaky intake gasket unless your water goes against gravity well I guess it could but chances are not much

[Morton]

scratch "inlet manifold" and make that "head"

but you're probably right Jase. how long does it miss for? I would have thought a flooded piston would clear up pretty fast

[greenfoam]

If you are lucky enough not to snap a conrod, they puff smoke for a fair while just with an injector

[fisher]

Injectors have been replaced along with most other components, it does not use any water, it misses for up to 30 seconds. All the compressions are 160 psi. I have been a mechanic for 40 years mainly on Diesels and this thing has me beat........

[Morton]

Sounds like something failing hardcore when not up to temp yet, eh? That's really strange.

Does it miss like it's dropped a cylinder? Or is it a really spluttery "oh no I'm running out of petrol" sort of miss.

[greenfoam]

Well if it's not injectors and you have new coils and dfi module it's got me beat :0. Does one specific cylinder go missing or two? or just a general once in a while miss

[greenfoam]

Morton get your own mind

[immortality]

leads and plugs? i had this a while ago, only did it after sitting for a few days. fine if i used it every day. from memory some injector cleaner fixed the problem. when did you replace injectors? ahve you changed fuel filter? have you checked fuel pressure?

[fisher]

Thanks Immortality i will try the injector cleaner. The injectors were replaced 12 months ago. Anything can happen in this industry.

[dumby9194]

replace your fuel pressure regulator.
to see if this is your problem the fuel pressure reg is located on the left side at the back of the fuel rail and is held on by an allen head bolt.
pull the small vacuum hose off that goes to the tb and see if there is a tiny bit of fuel in there if there is its stuffed this will cost 130 bucks.
Worked for my old mans vr it was hard to start then ran rough and blew black smoke for 10 secs