Idle fluctuation when i'm idling on idle. - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

95zilvia · 12-14-2004, 05:17 AM

When my car's warm, and I'm in neutral... sometimes the idle will jump up to 1500, then drop to 500-800, go up to 1500, then drop to 500-800. It'll keep doing this.

I think it could be several things-
Coolant temp sensor
Vacuum leak
Idle Air Control Valve
Atmospheric BOV???

Anyone can help me narrow it down?

Oh yeah, it's an S13 redtop.

***S14DB*** · 12-14-2004, 05:45 AM

I would say coolant temp sensor. They tend to give wild swings when they go.

nacstate · 12-14-2004, 09:54 AM

Mine does that when the fan kicks on, but I thought that was normal.

not so normal??

Dream240 · 12-14-2004, 03:14 PM

Quote:

Originally Posted by nacstate

Mine does that when the fan kicks on, but I thought that was normal.

not so normal??

It is normal for the idle to fluctuate when the cooling fans come on, same goes for when you turn on the A/C. But the revs should level off after a couple seconds.

nacstate · 12-15-2004, 09:13 AM

Quote:

Originally Posted by Dream240

It is normal for the idle to fluctuate when the cooling fans come on, same goes for when you turn on the A/C. But the revs should level off after a couple seconds.

ok thats what I thought, i'm good.

aznpoopy · 12-15-2004, 01:45 PM

i had the same problem.

massive oil leak from front main seal was gunking up my alternator. cleaned it off and resealed.

also, cleaning the electrical grounds in the engine bay seems to have helped alot too.

jumping up to 1500 is normal; but i don't think it should take a bit for it to level off at regular idle. mine goes up to 1500 and right back to 800rpms.

kingsol · 12-14-2004, 12:19 PM

did you check your injectors? my idle did the same thing before i found out i needed to replace an o-ring.

omen2853 · 12-14-2004, 01:26 PM

clean your AIV valve or just plain remove it. if that doesnt work, check for vacuum leaks, and go for the rest of those things you listed. first though, id check the AIV

95zilvia · 12-14-2004, 03:03 PM

So basically, everything is broken, haha.

12-14-2004, 05:17 AM	#1
95zilvia Nissanaholic! Join Date: Jun 2003 Location: South San Francisco Age: 40 Posts: 1,860 Trader Rating: (0) Rides Gallery: 95zilvia Feedback Score: 0 reviews	Idle fluctuation when i'm idling on idle. When my car's warm, and I'm in neutral... sometimes the idle will jump up to 1500, then drop to 500-800, go up to 1500, then drop to 500-800. It'll keep doing this. I think it could be several things- Coolant temp sensor Vacuum leak Idle Air Control Valve Atmospheric BOV??? Anyone can help me narrow it down? Oh yeah, it's an S13 redtop.

12-14-2004, 05:45 AM	#2
*S14DB* AFC #1 Join Date: Oct 2003 Location: 昨晩あなたのお母さんの家 Posts: 20,181 Trader Rating: (3) Feedback Score: 3 reviews	I would say coolant temp sensor. They tend to give wild swings when they go. __________________ Comments should be taken as Opinions not as Statements of Fact

12-14-2004, 12:19 PM	#7
kingsol Zilvia FREAK! Join Date: Jun 2003 Location: Berkeley/San Francisco Posts: 1,435 Trader Rating: (0) Feedback Score: 0 reviews	did you check your injectors? my idle did the same thing before i found out i needed to replace an o-ring. __________________ There is a time in every man's education when he arrives at the conviction that envy is ignorance; that imitation is suicide; that he must take himself for better for worse as his portion; that though the wide universe is full of good, no kernel of nourishing corn can come to him but through his toil bestowed on that plot of ground which is given to him to till. -Emerson

12-14-2004, 09:54 AM	#3
nacstate Leaky Injector Join Date: Jul 2002 Location: Greenville, NC Age: 44 Posts: 58 Trader Rating: (0) Feedback Score: 0 reviews	Mine does that when the fan kicks on, but I thought that was normal. not so normal??

12-15-2004, 01:45 PM	#6
aznpoopy Post Whore! Join Date: Mar 2003 Location: New Jersey Age: 44 Posts: 5,013 Trader Rating: (1) Feedback Score: 1 reviews	i had the same problem. massive oil leak from front main seal was gunking up my alternator. cleaned it off and resealed. also, cleaning the electrical grounds in the engine bay seems to have helped alot too. jumping up to 1500 is normal; but i don't think it should take a bit for it to level off at regular idle. mine goes up to 1500 and right back to 800rpms.

12-14-2004, 01:26 PM	#8
omen2853 Zilvia Junkie Join Date: Apr 2003 Location: california, usa Age: 44 Posts: 316 Trader Rating: (0) Feedback Score: 0 reviews	clean your AIV valve or just plain remove it. if that doesnt work, check for vacuum leaks, and go for the rest of those things you listed. first though, id check the AIV

12-14-2004, 03:03 PM	#9
95zilvia Nissanaholic! Join Date: Jun 2003 Location: South San Francisco Age: 40 Posts: 1,860 Trader Rating: (0) Rides Gallery: 95zilvia Feedback Score: 0 reviews	So basically, everything is broken, haha.