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High Revs, Bad Hunting

Trooper

By Trooper,
in General Maintenance

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Trooper Experienced

Trooper

Posted
Posted

I am having a lot of trouble sorting out this hunting problem on my R33.

When cold the car idles at 2000rpm, when warm idles at about 1500rpm, but sometimes settles back to about 800-900rpm which is nice.

We replaced AFM with a new one, didnt change anything.

The car seems to be much more settled when warm.

When cold the car jumps very quickly between about 700 to 2000rpm

I have cleaned AAC valve.

TPS sensor in PFC says 0.46V when car is turned off

AFM is about the same I think.

When driving AFM goes between 1.3V to 4V

O2 sensor goes up to about 0.9V

In the PFC menu I tried to adjust idle up and down in the settings, but it did not change at all...down to 200rpm up to 3000rpm and the revs stayed the same.

If you have any other ideas that would be appreciated.

On a side note my CAS has been wound right round to almost fully advanced (stock cam gear), is there any reason my tuner would have done this?

Thanks

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Trooper Experienced

Trooper

Posted
  • Author
Posted
It's a basic suggestion, but have you tried adjusting idle with the AAC screw?

Your idle control sensor could be rooted. Far as i know it's beneath the intake plenum.

haven't touched AAC screw, it was working perfectly before and nothing was touched, thats why i think its some sensor issue.

For the control sensor do I take off the intake plenum? Can they be fixed or should I buy a new one to try out?

Thanks

skybox 32 Enthusiast

skybox 32

Posted
Posted

i had exactly the same problem about a month ago.

guaranteed its your start up air regulator.. take that off undo the four screws and see if the spring has fallen off.. if it has hook it back up.. with mine the spring had fallen off thus screwing up my idle as too much air was getting pushed through at times and then not enough other times.

Trooper Experienced

Trooper

Posted
  • Author
Posted
Have you checked the SWITCH part of the TPS? (you've checked the SENSOR part already)

No I haven't, how do I do this?

guaranteed its your start up air regulator.. take that off undo the four screws and see if the spring has fallen off.. if it has hook it back up.. with mine the spring had fallen off thus screwing up my idle as too much air was getting pushed through at times and then not enough other times.

Is this different to the AAC valve? Because I cleaned the AAC valve and made sure the spring was free to move.

skybox 32 Enthusiast

skybox 32

Posted
Posted
No I haven't, how do I do this?

Is this different to the AAC valve? Because I cleaned the AAC valve and made sure the spring was free to move.

Yes, it is a different valve. Here is the tutorial on how to take it off and clean / check

http://www.skylinesaustralia.com/forums/Ai...nce-t69151.html

undoing the screws may be a bit of a mission :teehee:

Trooper Experienced

Trooper

Posted
  • Author
Posted
Yes, it is a different valve. Here is the tutorial on how to take it off and clean / check

http://www.skylinesaustralia.com/forums/Ai...nce-t69151.html

undoing the screws may be a bit of a mission :teehee:

Thanks for that mate, I actually read that tute and had a look for the air reg. on my RB25, couldnt see it and thought it must have been just an RB20 thing.

I will take off throttle body tonight, and add it to the list of things to check (doesnt sound easy based on that tutorial...I think ill pull the plenum off to make things easier)

Cheers - thanks heaps for the help.

Is there a way to test throttle position SWITCH?

I hope its the air regulator, or the throttle switch...its costing too much in fuel to keep driving how it is.

skybox 32 Enthusiast

skybox 32

Posted
Posted
Thanks for that mate, I actually read that tute and had a look for the air reg. on my RB25, couldnt see it and thought it must have been just an RB20 thing.

I will take off throttle body tonight, and add it to the list of things to check.

Cheers - thanks heaps for the help.

Is there a way to test throttle position SWITCH?

I hope its the air regulator, or the throttle switch...its costing too much in fuel to keep driving how it is.

all good mate! let us know how you go! btw when mine was playing up i was getting around 220kms out of a full tank so i know how you feel lol

blind_elk Grand Master

blind_elk

Posted
Posted

The air regulator (actually it's a cold start valve) is on the underside of the RB25 plenum.

The SWITCH part of the TPS needs to have 0 ohms across pins 1 & 2 (or maybe it's 2 & 3, can never remember). If it isn't correct, undo the retaining screws and rotate the switch until it is.

Trooper Experienced

Trooper

Posted
  • Author
Posted
The air regulator (actually it's a cold start valve) is on the underside of the RB25 plenum.

The SWITCH part of the TPS needs to have 0 ohms across pins 1 & 2 (or maybe it's 2 & 3, can never remember). If it isn't correct, undo the retaining screws and rotate the switch until it is.

I am finally going to fix this problem over the weekend (hopefully tonight)..

Can someone please confirm if I take the whole plenum off to get to the air regulator? I understand its a bit diff in the RB25, the tute i have been reading is for RB20.

Do I just check the spring when I get it off, and give it a good cleanout with contact cleaner? or do I need to test it with a known working one?

I will have a look at the TPS switch tonight, I have a multimeter somewhere which I will work out how to use tonight.

Thanks again - sorry to keep repeating questions...I have never had to sort out an issue like this before.

Godzilla32 Veteran

Godzilla32

Posted
Posted

The throttle closed sensor is what is also built into the TPS. It should read 0 ohms when the throttle is closed and infinity when its anything but closed. Your TPS voltage is about right so try to stay near .5v closed and 4.5-5v full throttle. I have my doubts it will be that if your chewing fuel also. It would just stuff your idle up. More inclined to think its the Air reg (cold start). Get it off and check its clean and all assembled properly.

Trooper Experienced

Trooper

Posted
  • Author
Posted
The throttle closed sensor is what is also built into the TPS. It should read 0 ohms when the throttle is closed and infinity when its anything but closed. Your TPS voltage is about right so try to stay near .5v closed and 4.5-5v full throttle. I have my doubts it will be that if your chewing fuel also. It would just stuff your idle up. More inclined to think its the Air reg (cold start). Get it off and check its clean and all assembled properly.

Do I need to take off plenum to get to Air reg ( cold start )?

  • 2 months later...
cmoney Proficient

cmoney

Posted
Posted

Maybe try checking your connections on your intercooler pipes. Ive got an RB20, & some of my connections were shit. The pipes are too short & the silicone pipes weren't sealing properly. I've had to put the clamps right on the end of the pipes really tight to stop the leaks. My idle was hunting all over the place, now its hardly missed a beat.

May only be an RB20 problem, but i would tend to assume its a Nissan forced induction problem in general. Hope this helps....

I am having a lot of trouble sorting out this hunting problem on my R33.

When cold the car idles at 2000rpm, when warm idles at about 1500rpm, but sometimes settles back to about 800-900rpm which is nice.

We replaced AFM with a new one, didnt change anything.

The car seems to be much more settled when warm.

When cold the car jumps very quickly between about 700 to 2000rpm

I have cleaned AAC valve.

TPS sensor in PFC says 0.46V when car is turned off

AFM is about the same I think.

When driving AFM goes between 1.3V to 4V

O2 sensor goes up to about 0.9V

In the PFC menu I tried to adjust idle up and down in the settings, but it did not change at all...down to 200rpm up to 3000rpm and the revs stayed the same.

If you have any other ideas that would be appreciated.

On a side note my CAS has been wound right round to almost fully advanced (stock cam gear), is there any reason my tuner would have done this?

Thanks

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