Missfire and Lumpy idle???

steves12 · #1 01-10-2007, 12:33

Not sure whats wrong but seems to be getting gradually worse. Got a missfire at idle but its not constant just missfires when it wants to ? Seems to clear up after bout 2000 rpm. Think it idles too low anyway so goin to adjust that but don't think that could be the cause? Oh and auto choke idle up thing doesn't work

Any help appreciated!!

JackieFan · #2 01-10-2007, 12:34

Have you got any mods?

steves12 · #3 01-10-2007, 12:37

Yeah but not much, straight thru exhaust, K&N 57i, bleed valve, blocked up the boost pop up valve thats all at the mo! Just wanted to get it runnin right before do loads more stuff

smoker · #4 02-10-2007, 18:52

Had my car on an exhaust gas analyser this afternoon and it was misfiring at idle when the mixture was set too lean >1.5 CO or so..might be worth turning the screw in clockwise on the MAF to richen it up and see if it improves.
I would guess that the bleed valve would cause some air to bypass the MAF and lean out the mixture off boost but should think this is neglible.
I have had trouble with non -nissan plug leads causing misfiring so if they are old or non-nissan they might be worth looking at.
On my second cold start idle control valve now and neither has worked properly so i'm just going to live with it now as the car doesn't actually stall and it saves petrol

. I guess a soaking in wd-40 might free it off but never tried this.

PukkaSilvia · #5 02-10-2007, 19:09

checking the ignition timing and inspecting your plugs and leads would be where i would start, then i would check for air leaks between the air flow meter and the throttle body. Then i would probably do a compression test.

steves12 · #6 03-10-2007, 10:52

Already checked for an air leak and orange turbo to turbo pipe seal is ripped so got on ordered £24

Ordered some nissan HT leads, distributor, rotar arm and some NGK BCPR7's.
Temperature seems to be running too low as well so ordered a new thermostat and coolant temp sensor.
As for the low idle when cold cleaned out the air regulator but no joy and nissan want £100 for a new one so might give that a miss for a while!

I'll wait for the parts to land in work an let you know how it goes!

zxocmars · #7 03-10-2007, 22:40

I had a similar problem and it turned out my leads were shagged.

New ones from Nissan (£58)

but worked a treat.
Strangely, Halfrauds list them at £39 a set, but say that they have no supplier to order them from

I also found the air filter to be upside-down, so christ knows how much shit got in there.

lmrdave · #8 04-10-2007, 07:49

My new HT leads cost £12.50 from a friendly motor factors, but I'm still having this problem. Well it was missing on boost, so got cooler plugs and it was fine on boost but now misses below 2K rpm.

new quality leads going on soon!

s13eater · #9 04-10-2007, 08:14

i think magnacor list them for the s12.

steves12 · #10 04-10-2007, 09:29

All my stuff just been delivered to work from Nissan

so tomorrow i'll have them all fitted, fingers crossed!

The leads were £45 for genuine nissan ones