Another IACV problem? Or something else? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

CantSTOP · 05-11-2011, 01:42 PM

I did some researching and the closest thing to my problem is a clogged/broken IACV or what sounds like it. Car is a 96 KA. Motor is completely stock.

Car turns on perfectly fine. I warm it up, after I drive it for a bit and come to a stop it'll drop idle and die. I'll start it up easy but it'll drop idle again and die, sometimes I get lucky and it starts up and runs normal. And when I'm on the freeway, I'll cruise at 70ish and it will start to bog and lose power for a couple seconds and then I can feel normal power kicking back in. Runs fine after that. But some days I get really lucky and don't have to deal with this stalling, other days its a pita T_T I've read to seafoam it, so it can stop the clogging.

I had a check engine for the knock sensor and I thought it was causing this problem. Bought a new one and replaced it and light immediately went away. After about 4 days later came back on but I haven't had time to check it yet.

Thanks for any help and sorry if this is a repost.

Another thing is, can the IACV be malfunctioning from a previous aftermarket header install? The EGR pipe was blocked off because it couldn't reach the header.

CantSTOP · 05-14-2011, 01:18 PM

Anyone?

The check engine light I got is P0443. Evaporative Emissions System (EVAP). I think I need to buy a new purge valve T_T

VG30Drift · 05-14-2011, 01:35 PM

IACV shouldn't cause that unless it was intermittently leaking or something. You could always just take it out.

trueno_spirit · 05-17-2011, 12:43 AM

The MAF sensor is most likely the culprit. I just fixed my car last month, it had the same exact problem. It would surge/hesitate while I was cruising on the freeway for a couple seconds then stop. When I came to a stop, I had to keep my foot on the gas pedal to keep the car running. The IACV seemed like the problem but it wasn't.

The problem with the MAF sensor is that the signal voltage will increase or spike up for a few seconds that the PCM misinterprets it and sends out more fuel to injectors. when this happens on the freeway, the car would bog and loose power. And more than enough fuel at idle would make to car to stall and die. you can see this with a Voltmeter or a Scope.

Block EGR passage way might cause surging or bogging on the freeway but it wouldn't affect the car at idle.

Like someone has mentioned above. The IACV shouldn't cause the car to bog or loose power on the freeway.

CantSTOP · 05-17-2011, 12:09 PM

^^WOW! That sounds about right, past couple of days its been the worst. Bogging for quite some time on the freeway. Dying at stops/lights. And it does try to send more fuel because when it bogs like crazy my gas mileage sucks

And did you get any smoke when you tried to keep the car running at a stop?

05-11-2011, 01:42 PM	#1
CantSTOP Zilvia Junkie Join Date: Aug 2006 Location: Soo-Cali(661) Age: 32 Posts: 590 Trader Rating: (12) Feedback Score: 12 reviews	Another IACV problem? Or something else? I did some researching and the closest thing to my problem is a clogged/broken IACV or what sounds like it. Car is a 96 KA. Motor is completely stock. Car turns on perfectly fine. I warm it up, after I drive it for a bit and come to a stop it'll drop idle and die. I'll start it up easy but it'll drop idle again and die, sometimes I get lucky and it starts up and runs normal. And when I'm on the freeway, I'll cruise at 70ish and it will start to bog and lose power for a couple seconds and then I can feel normal power kicking back in. Runs fine after that. But some days I get really lucky and don't have to deal with this stalling, other days its a pita T_T I've read to seafoam it, so it can stop the clogging. I had a check engine for the knock sensor and I thought it was causing this problem. Bought a new one and replaced it and light immediately went away. After about 4 days later came back on but I haven't had time to check it yet. Thanks for any help and sorry if this is a repost. Another thing is, can the IACV be malfunctioning from a previous aftermarket header install? The EGR pipe was blocked off because it couldn't reach the header. __________________ HI HATERS! from the left to the right

05-14-2011, 01:18 PM	#2
CantSTOP Zilvia Junkie Join Date: Aug 2006 Location: Soo-Cali(661) Age: 32 Posts: 590 Trader Rating: (12) Feedback Score: 12 reviews	Anyone? The check engine light I got is P0443. Evaporative Emissions System (EVAP). I think I need to buy a new purge valve T_T __________________ HI HATERS! from the left to the right

05-14-2011, 01:35 PM	#3
VG30Drift Zilvia Member Join Date: Sep 2007 Location: Santa Cruz, Ca Age: 32 Posts: 159 Trader Rating: (1) Feedback Score: 1 reviews	IACV shouldn't cause that unless it was intermittently leaking or something. You could always just take it out. __________________ '94 NA Z----------------'90 S13 Base Coupe

05-17-2011, 12:09 PM	#5
CantSTOP Zilvia Junkie Join Date: Aug 2006 Location: Soo-Cali(661) Age: 32 Posts: 590 Trader Rating: (12) Feedback Score: 12 reviews	^^WOW! That sounds about right, past couple of days its been the worst. Bogging for quite some time on the freeway. Dying at stops/lights. And it does try to send more fuel because when it bogs like crazy my gas mileage sucks And did you get any smoke when you tried to keep the car running at a stop? __________________ HI HATERS! from the left to the right

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05-17-2011, 12:43 AM	#4
trueno_spirit Users Awaiting Email Confirmation Join Date: Mar 2007 Location: sd Age: 39 Posts: 14 Trader Rating: (0) Feedback Score: 0 reviews	The MAF sensor is most likely the culprit. I just fixed my car last month, it had the same exact problem. It would surge/hesitate while I was cruising on the freeway for a couple seconds then stop. When I came to a stop, I had to keep my foot on the gas pedal to keep the car running. The IACV seemed like the problem but it wasn't. The problem with the MAF sensor is that the signal voltage will increase or spike up for a few seconds that the PCM misinterprets it and sends out more fuel to injectors. when this happens on the freeway, the car would bog and loose power. And more than enough fuel at idle would make to car to stall and die. you can see this with a Voltmeter or a Scope. Block EGR passage way might cause surging or bogging on the freeway but it wouldn't affect the car at idle. Like someone has mentioned above. The IACV shouldn't cause the car to bog or loose power on the freeway.