idle/rev problem - help!

[WazR32GTSt]

weird ass problem...

had the car for about 1.5 years and just recently have experienced my first 2 real problems

are they related?

NOTE: ITS AN AUTO!

1) noticed that sometimes when the car is v.cold (ie just leaving my street in the morning) when i am going v.slow (<30km/h) and i brake harder than normal, somtimes the car loses revs and then rises again, other times it stalls

i was thinking a leak in a hose going to the brake master cylinder??

2) more serious problem.

- had been driving for 45mins so car is definately at normal operating temp.

- At one point i am in stop/start traffic and just having to let off the brake and back on again its going that slow

- All of a sudden... car stalls (wtf?!). put it into neutral and re-start it... car stalls!

- so i turn on the hazards and let it sit for 10secs and start it again then give it a quick and small rev.

- now the car does th freikiest thing and revs to 2000rpm then drops to 1000rpm then revs ... drops... revs ... drops. happens about 5 times then car stalls again. (nb i'm not anywhere near the accelerator at this point)

- i let the car sit for 30secs (mind you its peak-hour traffic!)

- start it again and problem goes away... ????

- drive to work and go to park and the car stalls. i roll it into the park and walk off thinking it might go away when i come back (its called 'wishful thinking mechanical engineering'!)

- end of the day and i drive home from work and since then (2 days ago) the problem has never shown its ugly face!

what the hell is going on?

that night i cleaned the AFM and oxygen sensor and also re-set the ECU. not sure if it helped but maybe.

other possible causes i was thinking of:

- AAC valve

- AFM

- a plug somewhere that's loose

- leak in intake hose

keeping in mind this is an auto does anyone have any ideas?

and are the two problems possible related?

cheers,

Warren.

[mabru]

I'd check the usual suspects, AFM/connecter, AAC/connecter, or fuel delivery ie. fuel filter/pump. Definately run an ECU diagnostic, I know it's an intermittent problem but you never know.

-Matt

[timbar32]

Yeah what he said. Even reset ecu, clean afm, clean aac. Easy to do and has worked wonders for some of my probs, although mines a manual.

[krzysiu]

1) When u brake hard it uses power from the engine when u push the brakes. If u dont relize your rpm also goes up if u turn your steering wheel when you are not moving. Even if your lights are on the rpm does up. All this comtributes to it.

2) get it checked out by a mechanic

[R31 POWER]

Maybe chech the one-way valve above the brake booster?Did you have your foot on the brakes when it stalled all those times?

[heartbrkr]

i dunno,

just i recently had issue with teh auto stalling. first time was creeping in traffic around a round a bout, had to break heavily, car stalled.

next day i pull up outside my house, and it stalled. ended up changing the fuel filter. i think they are ment to be replaced at 100k, but mine is only 60k. wasnt using optimax however.

probably easy to flush, and not too expensive to replace. but then again, might be something else.

hb

[WazR32GTSt]

- fuel filter recently changed

- have re-set ECU and cleaned AFM and cleaned O2 sensor so will see if it does it again (may simply be this me thinks)

will take it to the mechanis if it happens again

possibly fuel pump? will this come up on ECU diagnostic?

keep the ideas flowing....

Waz.

[WazR32GTSt]

also... only got 370kms out of the last tank (not including fuel resevoir) when normally get 400+ so is it somehting to do with running rich?

[Col-GTSX]

Yep.... i had the same problem took over a grand and 3 months to fix

.... Go and buy an AAC valve and body....

Cost me $40.... time taken was less than 5 minutes

Problem fixed....

Mate many have had this problem, when i brought it up no one had an idea at all. Well they had ideas but as i fixed them the ideas were running out and so was my pocket money...

[Col-GTSX]

What happens...... is

1. The AAC valve eventually dies due to age/heat whatever it dies

2. a piece of crap will be suck in the spring that operates the AAC valve.

If you gonna buy a new Spring or clean it or what ever, you may as well get a new one.

[the phantom]

A NEW AAC costs about $450 new from Nissan unfortunately. I assume the $40 was for a used one? If not please share and I'll take a couple! I once had the AAC wire pin in the ECU plug somehow loosen and make an intermitant connection. I only found it accidently whilst fiddling around with the associated plug wiring and noticing the revs change when I nudged the wire.

Cleaning out the AAC thoroughly may restore it to working order unless the spool is worn and it's leaking. You cant take it completely apart unless your really keen though.

O2 sensors cannot be restored by any type of cleaning. They age chemically and once expired you need a new one. Typically they only last 45-50000 km.

[WazR32GTSt]

COL-GTSX - you are a champ... the AAC is coming off otnight for a clean!

will let you know how it goes...

[benm]

I bought some stuff to spray in the AAC but it looked like a hard job so I thought i'd check my AFM first. Then I couldn't get the 2 bolts off that hold on the snorkle so I thought what the heck I'll change my air filter (K&N Panel filter).

It is dirty but I didn't think like severly dirty enough to cause any issues. I put in just a standard no name air filter (doesn't feel any different in the drivers seat let me tell you) and my car is idling 300% better. It does hunt every now and then but a quick tap of the throttle fixes that. The revs don't drop sharply when I put my foot on the clutch/brake and it hasn't stalled yet.

I'll leave this no name filter in over the w/end and if it hasn't stalled by Monday i'll exchange the electrical contacts cleaner stuff for some K&N Cleaning oil and hopefully my problem will be solved.