Car Under-rev Then Stalled When Brake Hard

[Japav]

Hey guy,

just been experiencing this issue within the last couple days.....when i step on brake harder, car will goes under-rev at below 1000 rpm (normal idle at approx 2000~4000 rpm), then the handbrake and battery-like light came up...and if i dont step on the pedal to bring up the rev the car went stalled....

stalled has only happened twice so far, but iam still worry about it bcoz it never happen before

Its 2002 350GT-8, i am just about going for 90000km service...anyone got ideas on what might going wrong so i can tell the mech to check/repair

cheers

[andy65b]

Hey guy,

just been experiencing this issue within the last couple days.....when i step on brake harder, car will goes under-rev at below 1000 rpm (normal idle at approx 2000~4000 rpm), then the handbrake and battery-like light came up...and if i dont step on the pedal to bring up the rev the car went stalled....

stalled has only happened twice so far, but iam still worry about it bcoz it never happen before

Its 2002 350GT-8, i am just about going for 90000km service...anyone got ideas on what might going wrong so i can tell the mech to check/repair

cheers

I had similar problem last year with my M35.

Firstly your idle should be 650rpm +-50. So a max of 700 and a min of 600 when in Neutral. If you idle is up around 2000 rpm it sounds like you have a similar problem.

On the left bank of the motor when looking from the front is the PCV valve. This item is meant to be replaced around the 80k mark and when it fails it makes setting the idle impossible. The item is about $50 from Nissan and can be replaced by anyone including your self.

Have a read of this thread

http://www.skylinesaustralia.com/forums/M3...html&hl=pcv

It is all about what happened with my car.

Once the PCV is replaced they will need to do an idle air learning and idle reset done to the car.

You should also look at cleaning your throttle body as this can also effect the car when you step off the throttle.

I would suggest you do the 2 different things separately so that you can determine what is causing the problem.

Cheers

Andy

[fcruz3r]

+1^ 2000rpm is way high ...do the pcv thingy and also check for air hose leaks

[Japav]

whoopppsss.......just noticed I type extra digits for the rev...==' sorry it was early in the morning...

and now i cant edit the original post....

UPDATE:

just been experiencing this issue within the last couple days.....when i step on brake harder, car will goes under-rev at below "100 rpm (normal idle at approx 200~400 rpm)"

so this might rule out the possible PCV issue?

[andy65b]

whoopppsss.......just noticed I type extra digits for the rev...==' sorry it was early in the morning...

and now i cant edit the original post....

UPDATE:

just been experiencing this issue within the last couple days.....when i step on brake harder, car will goes under-rev at below "100 rpm (normal idle at approx 200~400 rpm)"

so this might rule out the possible PCV issue?

not really.... that idle is too low so some thing is out.

If the idle does not set between 600-700 then the computer does not remember the idle setting and other factors are dictating your idle.

2 factors caused the same problem on my car but I can not tell you which one was more important to fix but both have their issues.

1) the throttle body had a build up of residue that meant when you back off the throttle the butterfly closing meant no air could get around it and the motor stalled as per yours. The butterfly on these cars do not close 100% as there is no idle bypass.

So clean your throttle body and I think you will find this stops the revs dipping.

The second issue is why your idle is not set correctly.

When your throttle body is like this and closes 100% when backed off the car draws air from the only other available source which is the PCV valve. I believe this causes them to not work correctly and they are a part that is meant to be replaced around the 80k mark.

If the PCV allows air to pass through it al low revs it stuffs up the idle setting.

If you want to test if the PCV is faulty you can disconnect the PCV from the manifold, block off both ends, and try to reset the idle. If this gets the idle set correctly (600-700 rpm) then you know the PCV is faulty and you can order a new one.

I hope this helps.

Cheers

Andy

[scotty nm35]

While you are there, as Andy said, clean the throttle body and spray the airflow meter with some cleaner. Either of these could be the problem too.

Edited January 26, 2010 by scotty nm35