Slight Miss On Idle

[Dave32]

Hi Guys,

Just wondering, it seems that when my car is idling it has a really faint miss every couple of seconds or so, nothing major and it drives fine under load and makes good power, just wondering if this is normal? It's hard to describe but its kind of like instead of having a constant purrr for the idle every 2-3 secs theres a slight quiet and then it starts purring again.

anythign to be worried about? Car is an R32 GTR.

[K_E_V_I_N]

Yeha, i get the same..... S1 R33. revs dont drop, it's just a difference in the sound of the engine.

[RANDY]

Mine did that when my coilpacks were stuffed.. but it also did it badly up around 4500rpm.

Changed the packs to fix the high-rev problem, and now it idles perfectly! Two birds and one stone.

[Dave32]

so normal? or maybe a sign of uneven compression??

[bluey33]

I wouldnt say its normal but it does happen...

New coilpacks should do the trick...

As for compression, do a compression test. Its always good to know how your engine is going

[Craved]

tried new plugs?

[Link]

Id bet on it being new plugs before packs - mine is doing the same thing atm, its going for a service tomorrow anyway so that will fix it up

[Grunter]

Maybe injectors need a clean easy way to tell is

with a pair of long nose pliers clamp the fuel return

line (behind fuel preasure regulator) if idles better

this could be your problem.

[WazR32GTSt]

that's pretty normal

[dangerous_daveo]

I guess its fairly normal. Try new plugs first see if it helps. If not then get your injectors cleaned see if that works. I've just got my injectors done and its a fair bit better. Yet to see if there are any improvements in fuel economy yet tho.

[Cubes]

Mine has done it ever since moving away from the heat range 5 1.1mm gapped plugs.

If I open the gap up the idle smooths out.

The miss is stuff all but I guess it can be an annoyance if you expect it to be baby smooth. No such thing with a modified car.

[HR31_RB20DET]

Mine has done it ever since moving away from the heat range 5 1.1mm gapped plugs.

If I open the gap up the idle smooths out.

The miss is stuff all but I guess it can be an annoyance if you expect it to be baby smooth. No such thing with a modified car.

I found the exact same thing going from 1.1 to .8 gapped plugs.

[[mez]]

I found the exact same thing going from 1.1 to .8 gapped plugs.

Here here!

[ali-turko]

iv got his problem aswell and iv changed my plugs and put new spitfire ones on and no change

[700HP-GTR33]

iv got his problem aswell and iv changed my plugs and put new spitfire ones on and no change

This can also be caused by resistor pack and wiring to the resistor pack.

Or even earthing of the resistor pack.

Most get a lot of heat over the years and need some attention.

You will know there is a problem when you operate the air-con.(at idle) and it misses regularly.

[cpt_impossible]

Have we figured this out? I just changed from 5 plugs gapped to 1.0mm to 6 plugs gapped at 0.8mm and now I have this half miss stumbling sound coming from the exhaust every few seconds. Any updates?

Edited March 26, 2008 by cpt_impossible

[adam-__-]

Maybe get new coilpacks and clean the injectors like what others have said above?

I've noticed that this has started happening to my car as well. It's got splitfire coils and a change of the plugs about 3 weeks back and no change. A clean of the injectors might help, but too much a hassle. Everything is running good except for the idle so it doesn't bother me.

[Cubes]

Mine has always had a little pop with the sparky's gapped at anything less then ~1mm.

Richen the car up to 14.5:1 and the pop disappears. Mine currently idles and cruises a tad leaner than 15:1.

[SXY_33]

Yeah it happens when your spark plugs are gapped too close: from wiki

The gap adjustment can be fairly critical, and if it is maladjusted the engine may run badly, or not at all. A narrow gap may give too small and weak a spark to effectively ignite the fuel-air mixture, while a gap that is too wide might prevent a spark from firing at all. Either way, a spark which only intermittently fails to ignite the fuel-air mixture may not be noticeable directly, but will show up as a reduction in the engine's power and fuel efficiency. The main issues with spark plug gaps are:

· narrow-gap risk: spark might be too weak/small to ignite fuel;

· narrow-gap benefit: plug always fires on each cycle;

· wide-gap risk: plug might not fire, or miss at high speeds;

· wide-gap benefit: spark is strong for a clean burn.

A properly gapped plug will be wide enough to burn hot, but not so wide that it skips or misses at high speeds, causing that cylinder to drag, or the engine to begin to rattle.

I have mine gapped at 0.6 because my coilpacks are shit and i need new ones, but it fixes my hi-rpm misses, so until i save up for some splitfires i hav to put up with the missing at idle,

So yeah check the gap on your spark plugs, ideally should be 0.8

[Legumis]

I have the same idle-popping issue.

Regarding plugs, I've read that the amount of resistance with power getting to the plug can change the ideal gap for your engine. So I guess a lengthy trial-and-error testing period is going to be the best way to get things the way you like them.

Edited April 3, 2008 by Legumis