Idle up...

Ulrich C

Ulrich C

Hi guys.

Hope to get some advice, regarding the ilde on my K11 1,3 1993 Micra. Tried asking at a danish Nissan forum, but no replies for 3 weeks now, so that's not very active.

When I stop the car, the ilde sits pretty high for about 10-20 secs, before dropping to a pretty normal level again. My guess is around 1200-1300 rpm... fwn

It's quite annoying, but otherwise the engine runs really well.

Any idea if it's a quick fix at home, or something more complicated? I'm used to fixing stuff on the car myself, but don't have access to a garage and a whole lot of powertools etc.

Cheers, any help greatly appreciated! :)
 
Yeah, it will never die or anything. Just sits really high in the revs for quite a long time. Sounds like granddads driving...
My 4 other Micras have never been that way.
 
Oh just reread ur Q, u mean with a warm engine when coming to a stop u dip the clutch, throttle off but it keeps idling fast for longer than usual then drops to 750rpm?

Normally when in neutral or ur below 5mph in gear, whenever the revs go above 1k the ecu would fast idle briefly for 1sec by opening the IAC and then drop to 750rpm.

When in gear and above 5mph the ecu keeps the IAC open to fast idle so if u dip the clutch while in gear and above 5mph it fast idles at 1200rpm. This feature is so that the engine can maintain idle revs while under load from driving the wheels, ie following very slow traffic.

But if ur saying when u blip the throttle above 1k in neutral on a warmed engine and it takes over 2sec to drop back to 750rpm then the IAC might be sticky and needs cleaning to free up the mechanism response.

If the idle up/down feature responds in normal time but is generally reving too high during fast & nOrmal idle, then the idle bleed screw needs adjusting
 
Its this device located at the front of the TB
dsc03967r.jpg


Unscrew it off the TB n pull out. Carb cleaner in the moving valve and turn the inner moving bit with finger till its smooth non-gritty n wipe all clean.

Fit o-ring on tip of IAC with smear of wd40 n slip back on n reassemble.
 
wasn't tight on the IAC?
if there was only a slight resistive feel when u slotted the IAC back on (o-ring squeezing abit n sealing) and it warm idles at 750rpm i doubt it causes the issue.
tis only if it felt very loose (shrunk/perished o-ring) or very tight (o-ring has shifted off n become trapped) during fitting that there could be an air gap to hinder the IAC

does it cold idle at bout 1300rpm then warm idle at 750rpm?

i'd recommend removing the wax fast idle plunger mechanism on the TB then readjust the idle screw cos after few yrs they're certainly seized, confusing alota running issues and the IAC does most of the idle control sufficiently anyway.

wrote a related guide. ignore the IAV adjustment steps 1-9 in ur case

http://www.micra.org.uk/threads/430...mp-idle-speed-with-Nissan-Datascan?highlight=
 
Seems I can't access the link you gave me, maybe I'm too new here.

It constantly idles fast, I'd guess around 1300rpm.
There was a lot of green verdigris round the inside of the IAC which cleaned off ok, I noticed the IAC didn't seem to return fully, leaving a small air gap. I can turn it with my fingertip and all is smooth. Possibly a bad IAC?.
It's dark now, I'll have to live with it until next weekend now.

Roger.
 
ah so overall it idles too fast cold & warm.

k first thing i suggest is remove the wax mechanism, check it fast idles when cold then slows back down once fully warmed (showing the IAC works fine), then u adjust the idle speed screw behind the TB.

how to remove wax mechanism:

k750124.jpg


k550i466.jpg


warm up engine, adjust the TB idle bleed screw at the back till the idle speed is at 750rpm. advisable to also check the idle timings at 15deg too. blip the throttle then let the IAV settle to make sure it consistantly stabilises at 750rpm.
 
Ulrich C said:
Thanks pollyp!

I'll try and fix the IAC next weekend. Worth a shot for sure!

I'll let you know how it goes. :)

Ulrich
Click to expand...

if its constant 1300 rpm turn the hex idle adjust at the corner driver side of throttle body to lower when warm'd up fully ? ? ,,,,until weekend
 
I removed the spring and bracket from the wax mech as suggested. Now it idles at a steady 780 rpm when it's warmed up. The timing is @15 degrees with everything connected.

Thanks, pollyp!.(Y):)
 
Finally got around to doing it!

It was very easy. Took me about 10 minutes total. We'll see if it makes any difference after a longer drive and some changing weather.

Thanks again for the tip Pollyp! :)

Cheers,

Ulrich
 

Similar threads

villanueva_00
High Idle when warm
Replies
0
Views
250
villanueva_00
villanueva_00
C
Idle Adjustment
Replies
3
Views
197
CMF_DESI
C
Woody
Lumpy Idle
Replies
7
Views
2K
Woody
Woody
C
High idle and hunting. Please help.
Replies
6
Views
243
CMF_dreny
C
C
1994 (M) Micra stalling when idle
Replies
3
Views
163
CMF_asdame
C
Back
Top