idle going crazy

[sen-pai]

well i had a post on here saying that when i get off the freeway the rpms would stay around 1800 for about 5 seconds then drop to 800. but just recently when i start the car cold or hot it goes up to like 1500 then immediatley drops to like 400 almost killing the car and back up and down etc, until i rev it once then its normal? any ideas??? but other than that the car runs fine....just idles at about 1100..... wierd

[USCS14DUDE]

I had a similar problem with irregular rpms, i know my problem was a bad 02 sensor.

[sen-pai]

really....hmmmm i wonder if it could be something else

[240_believer]

mine jumps from 500-1000, makes me wonder also

[gyfer]

MAF, o2 sensor, vacuum leak, intake leak, IAA valve ....

ECU is trying to find right a/f , that's why rpm go up and down.

[sen-pai]

so those 5 things are most likely the prob... cause i mean the car runs great just idles funny when car is stopped.

[sen-pai]

well i just found out that these are the things that have been replaced recentlyfuel filterspark plugso2 sensor

spark plug wires have never been replaced and neither have the cap and rotor or pcv valve from what previous owners knows of. could those things that haven't been replace play a role in this?

[sen-pai]

ttt no1 can answer???? i'm sooo sad

[[s3]]

check for codes...

1st thing anyone should do

[nismojunkie]

my car idles weird, at about 700 then jumps to 1000 then drops back, it also makes a weird knocking/ticking noise when i accelerate. i have a differetn post where i asked about this and i was told it was most likely a vacume leak. http://www.nissaninfiniticlub....wpost

[[s3]]

my car idles weird, at about 700 then jumps to 1000 then drops back, it also makes a weird knocking/ticking noise when i accelerate. i have a differetn post where i asked about this and i was told it was most likely a vacume leak. http://www.nissaninfiniticlub....wpost

vacuum leak + timing chain guides

[gyfer]

so those 5 things are most likely the prob... cause i mean the car runs great just idles funny when car is stopped.

Vacuum leak. Bad injector. MAF maulfuction.i will check on vacuum leak first. check your intake.

[sen-pai]

timing chain guard y would that effect anything? any certain place i should start for the vaccum

[sen-pai]

what would i check on the intake??? could it possibly be the rotor and cap or spark plug wires cause i don't think those have been changed for like 3 years... they are on order either way they need to be replaced.

[Dauer]

check the coolant temp sensor for corrosion, my 240 had a very erratic idle, I disconnected the coolant temp. sensor and cleaned the connections w/ wd-40 and a toothbrush . Plugged it back in and taped off wiring, no problems have arised since

[gyfer]

good point Dauer.

Why check intake : he rubber pieces, going from MAF to throttle body, you might have leak.

If you do, MAF is not picking up the air that flow into your engine.

[knowleqe]

what lines to check for vacuum leak?

[[s3]]

what lines to check for vacuum leak?

After carefully reading the FSM, I would have to say...the vaccum lines.

[knowleqe]

haha, good one, but which ones are they? i have yet to get my FSM

[[s3]]

haha, good one, but which ones are they? i have yet to get my FSM

haha, just check the little rubber hoses going about in the engine, make sure none are frail or craking.

Replace as needed

http://www.hosetechniques.com has a nice sets made out of silicone

[sen-pai]

where can u order the fsm

[[s3]]

where can u order the fsm

If you're nice, I can let you download it

[nismojunkie]

i could use an fsm for an 89 240, if that is what you have, i would appreciate it if you would let me download it.

[sen-pai]

s3 ygm

[gounc14]

S3 what year fsm do you have?

[Neejay]

If you're nice, I can let you download it

Please?

[xxtrizz]

yeah I need the 89 90 FSM :P please hehe everyone has the 91-94 one hehe.

my car does the same thing but recently it hasnt done that. I believe it has to do something with the intake. Just make sure everything is snug and your MAF is ok.

Its air related I believe. I bought my car and it ran perfect. I pulled everything apart and put in my A/C and after I put it all back together it does that. So We checked the intake and then started her back up she only did it once and awhile. Then after winter she just stopped doing it again. So that is why im assuming its the intake.

[nismojunkie]

i was taking the intake off and i had to disconect the hose that runs off the side of it, and the hose broke off where it conects to a small black box. im no sure what this black box is for, but it leads to the end of my header (i think) the car runs fine with out the hose conected to the intake box, but can anyone tell em what it is for?

[Neejay]

i was taking the intake off and i had to disconect the hose that runs off the side of it, and the hose broke off where it conects to a small black box. im no sure what this black box is for, but it leads to the end of my header (i think) the car runs fine with out the hose conected to the intake box, but can anyone tell em what it is for?

AIV. Its not really important (except maybe for visual emissions), you can remove safely (go HERE )