Stumbling Idle... Searched and have tried everything else... - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Thieu · 11-05-2003, 03:20 PM

Okay, I have a 90 KA24E which runs great, but not at idle.
It have the AIV removed and all hoses plugged up. I just replaced the AAC (behind intake manifold) with one from the junkyard. At idle the car will sound crappy and stumble. It's not horrible but definitely annoying and it's obvious something is wrong. As it idles it will sporatically fix itself momentarily and idle nicely; the idle rises to 1000 as opposed to 700-800 when it's idling badly, and the exhaust stops sounding like its burping.

I have a new 300ZX fuel filter, cap, rotor, and a K&N intake. I just cleaned the MAF and my injectors are very recent.

There's a clear hissing coming from the intake at idle. Is it supposed to be doing that? When the problem fixes itself momentarily the hissing gets louder for a second. I've looked for vaccum leaks and found nothing; I even sprayed carb cleaner on them and nothing.

The only other thing I can think of is a leak in the intake manifold gasket or a dirty electrical connection.

This is driving me nuts... please help me...

stumpz · 11-05-2003, 09:42 PM

it might quite possibly be your timing..my friend drives a celica and it sounds like a really really WEAK domestic w/ the stumbling idle..fartcannon..heh it's because his timing is off...but hey i could be completely wrong.

Thieu · 11-05-2003, 11:33 PM

Quote:

Originally posted by stumpz
it might quite possibly be your timing..my friend drives a celica and it sounds like a really really WEAK domestic w/ the stumbling idle..fartcannon..heh it's because his timing is off...but hey i could be completely wrong.

Hmmm...don't think so. I just checked it a couple of days and it was dead on at 15 degrees.

A good idea though... keep 'em coming

Joel 180 · 11-06-2003, 12:31 AM

Sounds like idle air control valve failure or a manifold leak. Car is getting a little more air than its expecting so it overcompensates with more fuel

matlock · 11-06-2003, 05:10 AM

Hey its wierd, my car did nearly the same thing minus the hissing noise, but it just idled like a bucking bronco people would sit in my car and be like whats wrong with it is it even running on 4 cyl......so I changed the cap, rotor, plugs, and plug wires.....still did it. I was pissed I ran injector cleaner through etc...still did it I read on these forums and read on 240SX.ORG about the AIV and all that stuff tried all of those little tweaks and I don't know what it was. So then earlier last week I got my Cold Air Intake in the mail....I put it on and used the hoses they gave me and then I drove the car to see what it sounded and felt like after that (expecting the intake to be all cool, which it was in a sense) but then later on after being all pumped on some CAI Inoticed the idle was normal...then I thought well maybe its just not doing it right now, or maybe I am used to it.....I cruised to a friends house and he noticed right away it was all better.....I am not sure what this fixed my best guess is that maybe the MAF was dirty or the old hoses were shot, but I guess me rambling on telling a really stupid story didn't help at all.....When you said hissing I thought Vaacum leak but if you checked it then you might not be having that problem.....okay now this might sound stupid again but my friend rebuilt his KA basically and it was all together and we had it timed and everything but it wouldn't idle and then when it did it was like on the verge of dying, so he is good friendswith the nissan mechanics and they told him vacum leak off the intake manifold.....we could not pinpoint a leak, and out of frustration he tightened the bolts down more on the intake manifold then I started the car and wham it ran fine......I do not know if anywhere in this endless rambling I made sense and I don't care if I am flamed I am just telling you what worked for my friend and I and Maybe it will sole your problem.

Thieu · 11-06-2003, 11:47 AM

hehe... I appreciate the story...

I'm pretty positive that it's my intake manifold. I'm going to take it off this weekend, clean the inside of it well (it's pretty gunked up) and replace the gasket.

I'm also taking off my door panels and glove box and taking the fabric off. They will get replaced with a better fabric...

91rusty240sx · 11-08-2003, 06:16 AM

did you clean out your throttle body as well? try to clean your coolant temp sensor as well, it worked for me.

11-05-2003, 03:20 PM	#1
Thieu Zilvia Member Join Date: Sep 2003 Location: tx Posts: 199 Trader Rating: (0) Feedback Score: 0 reviews	Stumbling Idle... Searched and have tried everything else... Okay, I have a 90 KA24E which runs great, but not at idle. It have the AIV removed and all hoses plugged up. I just replaced the AAC (behind intake manifold) with one from the junkyard. At idle the car will sound crappy and stumble. It's not horrible but definitely annoying and it's obvious something is wrong. As it idles it will sporatically fix itself momentarily and idle nicely; the idle rises to 1000 as opposed to 700-800 when it's idling badly, and the exhaust stops sounding like its burping. I have a new 300ZX fuel filter, cap, rotor, and a K&N intake. I just cleaned the MAF and my injectors are very recent. There's a clear hissing coming from the intake at idle. Is it supposed to be doing that? When the problem fixes itself momentarily the hissing gets louder for a second. I've looked for vaccum leaks and found nothing; I even sprayed carb cleaner on them and nothing. The only other thing I can think of is a leak in the intake manifold gasket or a dirty electrical connection. This is driving me nuts... please help me... __________________ 90 240sx daily driver/project car "SOHC it to me"

11-05-2003, 09:42 PM	#2
stumpz Leaky Injector Join Date: Jul 2003 Location: Chester, Virginia Age: 39 Posts: 84 Trader Rating: (0) Feedback Score: 0 reviews	it might quite possibly be your timing..my friend drives a celica and it sounds like a really really WEAK domestic w/ the stumbling idle..fartcannon..heh it's because his timing is off...but hey i could be completely wrong. __________________ ghetto

11-06-2003, 11:47 AM	#6
Thieu Zilvia Member Join Date: Sep 2003 Location: tx Posts: 199 Trader Rating: (0) Feedback Score: 0 reviews	hehe... I appreciate the story... I'm pretty positive that it's my intake manifold. I'm going to take it off this weekend, clean the inside of it well (it's pretty gunked up) and replace the gasket. I'm also taking off my door panels and glove box and taking the fabric off. They will get replaced with a better fabric... __________________ 90 240sx daily driver/project car "SOHC it to me"

11-06-2003, 12:31 AM	#4
Joel 180 Leaky Injector Join Date: Aug 2003 Location: Perth Posts: 56 Trader Rating: (0) Feedback Score: 0 reviews	Sounds like idle air control valve failure or a manifold leak. Car is getting a little more air than its expecting so it overcompensates with more fuel

11-06-2003, 05:10 AM	#5
matlock Zilvia FREAK! Join Date: Jul 2003 Location: California Age: 40 Posts: 1,169 Trader Rating: (0) Feedback Score: 0 reviews	Hey its wierd, my car did nearly the same thing minus the hissing noise, but it just idled like a bucking bronco people would sit in my car and be like whats wrong with it is it even running on 4 cyl......so I changed the cap, rotor, plugs, and plug wires.....still did it. I was pissed I ran injector cleaner through etc...still did it I read on these forums and read on 240SX.ORG about the AIV and all that stuff tried all of those little tweaks and I don't know what it was. So then earlier last week I got my Cold Air Intake in the mail....I put it on and used the hoses they gave me and then I drove the car to see what it sounded and felt like after that (expecting the intake to be all cool, which it was in a sense) but then later on after being all pumped on some CAI Inoticed the idle was normal...then I thought well maybe its just not doing it right now, or maybe I am used to it.....I cruised to a friends house and he noticed right away it was all better.....I am not sure what this fixed my best guess is that maybe the MAF was dirty or the old hoses were shot, but I guess me rambling on telling a really stupid story didn't help at all.....When you said hissing I thought Vaacum leak but if you checked it then you might not be having that problem.....okay now this might sound stupid again but my friend rebuilt his KA basically and it was all together and we had it timed and everything but it wouldn't idle and then when it did it was like on the verge of dying, so he is good friendswith the nissan mechanics and they told him vacum leak off the intake manifold.....we could not pinpoint a leak, and out of frustration he tightened the bolts down more on the intake manifold then I started the car and wham it ran fine......I do not know if anywhere in this endless rambling I made sense and I don't care if I am flamed I am just telling you what worked for my friend and I and Maybe it will sole your problem.

11-08-2003, 06:16 AM	#7
91rusty240sx Zilvia Junkie Join Date: Oct 2003 Location: Los Angeles, CA Age: 39 Posts: 467 Trader Rating: (1) Feedback Score: 1 reviews	did you clean out your throttle body as well? try to clean your coolant temp sensor as well, it worked for me.