idling problems

[babs]

i've got an r33 gtst, and roughly once a week i get an idling problem for about 15 secs once i start the car.

what happens is once i start the engine, the revs (like always) first jump up to roughly 1400rpm or so, and instead of dropping down to 1100rpm for a minute or so it keeps jumping up and down between 600 and 1400rpm. this happens for about 15 seconds and if i give it a bit of throttle, eventually it stops and idles normally again... and like i said before.. what spins me out the most.. is that it only happens once a week or so...

was told by a novice (like myself) that it could be a leaky bov??

:confused: !!!

help please!

babs...

[MonstaS4]

Doubt it will be BOV, cos it's before the throttle butterfly. Maybe cold air bypass valve or coolant temp sender. Try some electrical cleaner on the plugs of these two.

[The Alchemist]

it could be a inlet manifold gasket leak, has happened to me with the GTR, took me ages to diagnose!!!!!I mean Hours and hours....looking at the ICS and the cold start valve etc etc .

grap your self a can of brake cleaner in a aerosol can preferrable one with the small white tubing you can stick in the nozzle, like on those cans of CRC, and run the car,

carefully and I mean carefully coz this stuff is flammable, spray along where the inlet manifold meets the side of the cylinder head. Also spray into the injector bungs where the injector nozzle sits in the inlet manifold.

I had about 1inch missing in my inlet manifold gasket and 3 of the 6 injector bungs very leaking like a sieve!. The vacuum sucks in the flammable brake cleaner and it will cause a very noticable engine stumble. You'd have to be deaf to miss it.

Give that a try, can save you hours and dollars.

If the ICS or the cold air valve were faulty the idle would usually stay high all the time even when warmed up.....Checking them however is relatively easy so start with the brake cleaner and go looking for vacuum leaks first....

[rb25]

good advice Alchemist.

-rb25

[babs]

ah k, thanx for the tips monstas4 and alchemist..

ill try both of those things and see how i go... i also found another thread with someone having similar problems.. se if those suggestions help thanx again..

[Topkart R33]

Check radiator coolant sensor on bottom left side of radiator(green plug up top) Check with multimeter to see if u got a circuit. Mine has the same problem but havn't gone to Nissan yet to get a new one.

(Just found out that sensor is actually for the electric fan,my mistake) :Oops:

[swalesy]

happened to me too check lambada controlis working .fool mechanic turned mine off but on now and works fine

[benm]

it could be a inlet manifold gasket leak

Apart from the rough idling what other problems can this cause? Flat spots higher in the rpm? Popping from the exhaust on down shifts? Weird on/off boost?

[babs]

Apart from the rough idling what other problems can this cause? Flat spots higher in the rpm? Popping from the exhaust on down shifts? Weird on/off boost?

hmmm i do seem to be experiencing this too.. but without the exhaust popping..

have got flat spots occasionally and boost is very unpredictable.. very wierd i must say