Idle speed to high.

hi,
i'm from portugal and i have a nissan micra k11 1.0 that,
on the first star the idle speed goes to high, and i can't find the cause. i have one tube disconeted, " i think" but i can't find were to connect it. you can see the tube on the image. can someone help me please.

Thanks

does that tube go to the gearbox breather ?
and if your idle is too high only when cold, it may be a waxstat problem (at the rear of the throttlebody)

frank

hi,
yes the tube come from gearbox breather.
i buy this car a few days ago and i'm trying to repair it,
this tube is supose to be this way?
what is the waxstat problem?
sorry for my english

thks
Carlos Brito

Well, i was just wondering...can you regulate the idle speed through a potentiometer? Micras 1.3 manual TM have pretty low idle 600-650 (warm).
I was wondering, if you can play with regulating the idle speed or you need it connected to a PC unit?

Thanks,
Alex

Hi Alex,
this is 1.0 manual but the idle speed is the same and at warm temp i think that is ok, i can't see because i don't have a rpm meter. theres another problem, is when driving and coming to stop the idle stays hi until i totaly stop the car.

Thks
Carlos

that g/box breather does,nt go anywhere carlos, and the waxstat just holds the throttle open for a fast idle when cold,
i think you can set the idle control valve via the diagnostic plug and software alex, or else manually via the black plastic hex screw on the rear corner of the throttlebody

frank

Could be many things...

I'd recommend cleaning the throttle body, re-soldering all the intake tubes making sure there is no leaks, checking the spark plugs, wires to spark plugs, but mostly checking the MAF sensor on the throttle body. There's a guide here showing how to re-solder your throttle body....it ain't hard work and helps a lot.

I had problems with my old one, the car was dying on me when i was stopping, thats actually the opposite of your problem :).
About my question, would be grateful if someone helps on it:

- Can you regulate the idle speed through a potentiometer, without editing all the data through a PC connected to the ECU?

I was looking at the famous "re-soldering your TB guide" and the guy circled a part, saying its a potentiometer where you can regulate idle RPM....i cant see it, does it exist, where?

Thanks guys,
Alex

that potentiometer is the throttle position sensor alex, and the idle screw is near it (on the rear corner)
you are supposed to remove the t/p/s plug while you adjust the idle screw, then replace it after

frank

Hmmm thanks frank2, seems i'll have to look for that hex screw and play little with it. Wired, i couldnt locate it :) Got any clear pic to see it?

As i said the car runs without any problems, the only "problem" is that Micras have low warm idle (600-650) as i checked in Autodata. Making it 700-750 will probably get rid of the shake feeling when ideling warm.

Thanks,

this one alex, it basicly bleeds air past the butterfly

frank

hi,
I've just already done the resoldering job of the trothle body because the idle was up and down and the car lose power, after the resoldering the idle stays high at cold and when the car is running and only goes down when stop.
the waxstat have any regulation?

Thks Carlos

@frank2: A nice, that's a clear picture.

So what do you recon?...turn the engine, drive it ~30min till it warms up "warm idle" kicks in, and then play with that screw? Am i right? Suggestions? Thanks again ;)

there,s a screw on the quadrant for the waxstat carlos, and i think the ecu acesses signals from the neutral switch and the speed sensor, you may need a bit more tweaking eh

frank

hi, Frank
can you show me the screw or the me more specific were it is?
the neutral swicth is on the gearbox correct?

Thks
Carlos

So frank2, any ideas?

like i say alex, remove the t/p/s and set the idle with that screw eh :)

and the waxstat pushes on the screw carlos (top arrow)
which holds the quadrant open a bit (lower arrow)

frank

thanks for the pic Frank
i'm going to try it.

Sorry if im asking a lot, i like being precise :)

So all it is to do is removing the TPS sensor, and playing with that screw and hearing the sound of the idle right? (as i dont have RPM meter yet)

But the engine must be fully warmed up before i disconnect the TPS sensor and play with that screw or it can be cold?

Thanks for all your replies, you've helped alot :)

yes alex, haynes says to get the engine warm, disconnect the t/p/s, blip the throttle a couple of times, then set the idle with that plastic screw :)

frank

Thanks man....i'll try it as soon the weather gets better :)

Will report back ;)

See ya :)

hi,
the cold start idle it's ok, thks to frank.
i'm going to check the neutral swicth and the speed sensor.
can the neutal swicth be removed?
the speed sensor is on the distributor?

thanks for the help

Carlos

if its a pre-98 1.0 carlos, its a combined neutral/reverse switch i believe (4 wires on the g/box)
and if its cable speedo, i think the speed sensor is in the cluster/clocks

frank

Hi,
yes is 1994 1.0 and have a 4 wires on the g/box and i have no rear shift light to, i've check the lamp and it's ok check the suport and don't have voltage there. i think the swicth is faulty but i don't know if i can remove it.

Thks
Carlos