Jump to content
SAU Community

Recommended Posts

Hey guys,

One thing that has become more apparant as of late...

When the car is not up to operating temp yet, sometimes the car will hunt when it's idling at the lights. It doesn't happen all the time but does happen quite often.

Has anyone experienced this and possible solutions?

I've had a search and found a tutorial on cleaning the AAC valve : http://www.skylinesaustralia.com/forums/in...110431&st=0 but it says that the AAC valve only comes into play when the car is warm, not cold... and theres no real problem when warm.

The car is a 1996 R33 GTS-t.

Cheers

Edited by lordsnipe
Link to comment
https://www.sau.com.au/forums/topic/162029-r33-hunting-when-cold/
Share on other sites

No, I never said the AAC valve doesn't work when its cold. What I said was there is a valve under the AAC which is the cold start valve. It allows more air in at cold idle rather than hot idle, this is why cars rev higher when cold.

The AAC is like a stepper motor, and is controlled by the ECU. It can most definitely affect the car when cold, however it is not the only fix there are numerous reasons why a skyline idle hunts.

If it only affects the car when cold I would start looking at the water temp sender, cold start valve and work my way from there.

Hey all, i have a bit of a question..

my rb25det idles at like 900ish all the time.. at cold and at warm.. i have read about the AAC vale and to be honest i dont think cleaning thats going to fix it.

My car doesnt have ANY idling issues or anything wot soever.. im basing my theory that either the temp sensor or the cold start valve is buggered..?

What i want to know is that is it possible to clean/fix the cold start valve? is it something that you can adjust by turning with a screw driver?

Thanks :sick:

No, I never said the AAC valve doesn't work when its cold. What I said was there is a valve under the AAC which is the cold start valve. It allows more air in at cold idle rather than hot idle, this is why cars rev higher when cold.

The AAC is like a stepper motor, and is controlled by the ECU. It can most definitely affect the car when cold, however it is not the only fix there are numerous reasons why a skyline idle hunts.

If it only affects the car when cold I would start looking at the water temp sender, cold start valve and work my way from there.

Why clean your AAC Valve/ What does it do?

When your RB series motor is warmed up and idling it is your AAC valve which controls the amount of air entering your engine in order to control your idle.

I took that as it only takes effect when warm .. in any case, i'll have a look at your suggestions and go from there.

Cheers

There are acually 3 valves all up in the car. There is the FICD, fast (first) idle controll device, as per nissan fast, this is the little PURPLE plug selenoid, all it does is open and closes to compensate for AC load.

The ACC valve BROWN PLUG, regulates the engine RPM at idle, it controlls the idle to the motor. It work HOT and COLD, any time the car idles. IF this valve is stuffed or dirty, the car will hunt.

There is also a COLD START VALVE, or IACV according to FAST, this is located below the intake plenum and sux to remove, i cut my hands up big time.

This valve controlls the amount of cold air entering the plenum on a cold engine. It houses a sliding disc and a bimetalic strip, which allows for expantion and closes the dick.

This does tend to stuff up, as i found out, it is suppose to be fully open below 20 deg and fully closed after 60 deg C, mine never opened more then half way. I need a new one. $208 from nissan, so i am hunting a second hand one.

If you have hunting, i suspect there are several problems. ONE, your throttle body and butterfly are dirty and not sealing propely. When the cold start valve is open and the butterfly is not closing propely, the acc valve tries to wind the air back, and teh engine will hunt.

OR thhe ACC valve is dirty or fauly, take it all apart and clean WELL with carb cleaner and brushes.

Also possible that the engine temp sensor is a little out of wack, and teh engien is trying to add more/less fuel and the ACC valve tries to compensate for this.

I have had cold start issue for the past 1-2 months, and no one, and i mean no one, can find what is happening, everyhting has been checked, rechecked, and still nothing, Time to swap over all the components and go from there.

Hey all, i have a bit of a question..

my rb25det idles at like 900ish all the time.. at cold and at warm.. i have read about the AAC vale and to be honest i dont think cleaning thats going to fix it.

My car doesnt have ANY idling issues or anything wot soever.. im basing my theory that either the temp sensor or the cold start valve is buggered..?

What i want to know is that is it possible to clean/fix the cold start valve? is it something that you can adjust by turning with a screw driver?

Thanks :rofl:

Have you adjusted your idle screw?

AAC and idle screw, cleaned and adjusted these 2 and solved so many problems:

Idle would eventually sit around 1200rpm after jumping back and forth between 1,000 and 1200 now it sits at 700

Car would have a slight miss on idle (had a lot of idle problems :happy:), now fixed

Vacuum hose (the small thin tube) had a crack down the side of it, had been wondering what the hissing noise coming from engine bay was, now fixed.

Car is so much more responsive now, sounds better overall and performs better. Even if you arent having problems with idle id still recommend cleaning it out if you havent already.

This is a long shot idea i was told about and i am still a bit skeptical about it but might b worth a try.

Been told when the car is cold the ecu automatically makes the cars idle jump a lil to try warm it up. If the thermostat is jammed open this means the car is gettin fed cold coolant and can take alot longer to get up to temp. SO as such the engine remains cold and the idle jumps a lil to try increase engine temps. Then after a while all the coolant has gone thru the engine and is at a temprature that the engine itself is warm and the idle settles down.

As i said i'm a bit skeptical about that whole idea does sound like one of them bullshit storys a dodgy mechanic might feed you to try hide the fact they have no idea what a cars problem is.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Seat of the pants assessment of the new intake: The car is way less "doughy" when hitting the loud pedal, especially off idle when stopped or in traffic, I did use a cheapo lazer thermal thingo to measure the temp around where the pod filter got its air, it was between 55 - 60°C, in saying this the car was shut off and not moving, so the OEM intake pipe was not supplying any fresh air to where the pod was when the car was at least moving A weird bonus was induction noise on the throttle in the cabin increased a bit,  I was worried that I was actually going to lose some of that induction noise I love so much, outside though, when I got the daughter to do a WOT drive by pass for me, the induction noise has increased alot when on the throttle, not quite ITB doort, but well up there I'm extremely happy with the results and have been exploring the country roads in the region  As for house mods: 1.New front fence is up and is awesome, it really upgraded how the joint looks from the street, and the added security is nice 2. Electricians have replace some interior lights, and with more lighting in the garage, a few new motion detecting lights out the front above the garage, front room, and at the front door, which I have already found heaps helpful coming and going, also now has fancy pants CCTV all round the house The only hold point for power though is the solar and batteries due to supply issues, although this will happen over the next few weeks 3. I have done a heap of landscaping out the front and I'm almost ready to do a new small retaining wall with some nice blocks to replace the brick and cemented in rocks around the raised garden beds cemented in river stone "was the fashion at the time" the house was built. I currently have a pallet of retaining wall blocks and 2 bulka bags of 20mm blue metal to replace the wood chip that is in the raised garden beds around the house 4. I now have 3 big raised garden beds for out the back to grow some vegetables, about 70cm high, 200cm long and 100cm wide 5. My 2 compost bins are already pretty full with brown, green and kitchen waste from the landscaping I'vedone so far, but they will probably take a few months to break down, so anything else that gets chopped, trimmed, and kitchen waste will just start filling the base of the raised garden beds to about 30cm before I start throwing 40cm of good compost, and stuff, for the vegetables to grow in, I'll need a few ton of compost and soil, but the local supplier can sent me bulka bags of the stuff Basically the logs, wood chips and a few strategically placed rocks for drainage, will give the beds some good organic materials down low to break down over time, and they will hold moisture during the warmer months to save the water in my big arse water tank if we don't get alot of rain So, all in all, the car and house mods are going well, and I'm really enjoying being retired, I sleep in too 0700 and slowly plod around inside until I feel like actually doing anything, and only work in the yard for as long as want, which has actually been alot over the last few weeks,  although when you look at it, it seems that not a huge amount of work has been done,  until I look at the before I started the work pics Happy days and good times indeed 
    • hahaha yeah. Plan is to get side skirts and probably just rear pods. But going to do them one-by-one. I've got a set that I really like from RHDJapen, but that one isn't shipped to AU. So need to find someone who can get it for me
    • Here's an idea, answer the questions I asked you as they are trying to work out WHY the LSD will be binding up in a straight line.
    • You haven't driven many modern cars then have you? Most of them have sfa steering feel with their stupid electric bullshit steering systems.
×
×
  • Create New...