Idle Dips at Complete Stop

[powersteeringless180sx]

About every other time I come to a complete stop my idle will start dipping and stall if I don't feather the throttle. I also found out my idle would go back up when I start pumping on my brake pedal. I'm thinking it's my brake booster. Can anyone confirm?

[GSXRJJordan]

Could just be the vacuum line going to the brake booster - it runs from the back of the intake mani up over the brake hardlines, and takes a lot of heat. Try replacing that first.

[bcbs13det]

what motor and what bov.
if an sr then sometimes if you arent runing recirc it will do this.
maf based systems do it alot when you run atmospheric blow off.

is there a check valve in the vac line for the brake booster?

[smelly240]

is the car boosted? if not disregard the bov talk. And start looking if it does it only when u hit the brakes and whatnot. if so - start at the booster - if not look eslewhere.

[g6civcx]

Check the one-way check valve between the booster and the manifold. The valve should only open one way to let vacuum into the booster. Vacuum should not be going the other way.

[Matej]

My car does that when my MAFS is loose, check if yours is plugged in all the way.

[powersteeringless180sx]

My car does that when my MAFS is loose, check if yours is plugged in all the way.

naw for sure my maf's connected and secure.

Could just be the vacuum line going to the brake booster - it runs from the back of the intake mani up over the brake hardlines, and takes a lot of heat. Try replacing that first.

yea i'll try replacing that vacuum hose. it doesn't even feel like rubber anymore. it feels more like a hard piece of plastic now from all the heat.

Check the one-way check valve between the booster and the manifold. The valve should only open one way to let vacuum into the booster. Vacuum should not be going the other way.

i'll try checking the valve when i get some free time during the day.

[powersteeringless180sx]

update

i checked my hoses that go from the booster the motor. the hose is a lil hard but there aren't any cracks or leaks on it. i ordered a new brake booster check valve from westco nissan a couple days ago. still waiting for it in the mail. i'm gotta refiberglass and bondo my bumper tomorrow. so while the bondo dry's i'm gonna change out my pcv and my fram fuel filter to a nissan one. maybe changing those out will help.

[greddyguy]

mine does the same exact thing. i need to figure it out as well.

[Antihero983]

post up pics of when you replace your PCV. ive been told its a bitch to get to....

[S14DB]

On the KA,
Undo the ALT bolts.
Remove the belt.
remove the top bolt on the alt.
swing the alt so it hits the frame rail.

This should give you lots of room to work on the pcv. If not pull the bottom bolt and remove the alt completely.

You may want to buy a catch can and put it inline between the pcv and the T bar on the manifold. This will filter all the nasty vapors and crap coming out of your block into your manifold.

[bziggers13]

my newer daily does it too..
lights dim, idle drops 50 or so.

I thought my alt was bad, never got around to replacing it. too lazy.

[unicoladron]

i had the SAME exact problem but wasn't related to brakes. i set my CAS timing and cleaned my IACV and my idle problems went away, it was great. but yeah, i had to do the same thing (feather the throttle) to prevent the idle from going so low. Also it is a known problem when SR's (or perhaps any other 4cyl engine) have lightened flywheels. but the idle doesn't drop to 50, it drops to more like 550-700.

it appears he has an SR due to the red SR icon he put in the title.

note: i believe the brake booster line is supposed to be hard so it doesn't flex and pinch under all of the vacuum suction...

anyone have a new car to actually confirm this?

[S14DB]

Bah, is this a KA or SR then?

[powersteeringless180sx]

sorry if people got confused but i have an SR. i thought the red SR symbol was enough to indicate it. The pcv was super easy to change out since it's on the rear of the valve cover on the intake side.

i changed out the pcv and fuel filter today at my buddy's house. i drove home and idle seems to be stable at 850 w/ no dipping at the stop light. so far so good. i'll be putting in the brake booster check valve next.

[240trooper]

my friend has the same problem but with his 91 ka , goes to a fast stop and car dies , we changed tha alt didn't fix it , is has a rebuilt maf so thats not the problem . today we riped off the intakes mani off a extra 95 ka laing around at his house , the pcv's at the bottom , ima tell him to change that and see what happens. my old sohc was so much easier to fix lol . I thought maybe it could be his egr..

[powersteeringless180sx]

drove around today and it's still dipping every now and again. still waiting for the check valve. if that doesn't fix it i guess i'll check my cas timing next.... argh...i don't feel like buying a timing gun.. i just want my shit to run right.

[S14DB]

http://www.boostpro.net/prodtester.html

[powersteeringless180sx]

i installed the check valve and still the same thing. i put in some fuel injector cleaner in a couple weeks ago and the car has actually been idling like a champ until this week. it started dipping again and idling rough but not as often. so now i'm assuming it's a fuel problem? i'm gonna get an inline fuel pressure gauge to see if the fp is normal.... i dunno..... the search continues.

[powersteeringless180sx]

i cleaned out my throttle body and iacv valve over the weekend. my idle's been pretty stable and hasn't dipped at all durning stops. so far i think i've solved my problem.

[A Spec Products]

When I had my KA a while ago, I had similar issue

Revs would dip low (almost dying) at stops

It was the coolant temp sensor (the one at front of motor by upper radiator neck I think?)

Sometimes they go bad, and the wires from the harness get corroded

I got a new sensor, respliced new wires from the point where it was corroded/not corroded, and after that it was all good

I'm not a mechanic though, so not sure if that is your problem

[98koukile]

Mine did this when I needed a new o2 sensor, I'm sure you would have thrown a code though