S14 sr20 weird IACV issue advice - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

zrs6v4 · 04-15-2012, 01:02 AM

I have a 95 240sx with s14 sr swap. Its clean but has been running rough from idle to about 3500 rpms. When cruising at 3,000 rpms it cuts out a bit. I believe I have it to the iacv, but maybe you can chime in. I pulled the iacv vacuum hose out of my intercooler piping so the iacv would not get vacuum or whatever. With the vacuum to the iacv off the car runs perfect except dies if i dont keep reving it when stopped but with the iacv vacuum on it runs terrible. Ive never had an iacv issue so im not sure if i need to just clean it or if i needed to replace it.

Any advice?

WindyCity · 04-15-2012, 02:40 PM

i had a similar problem to this. it turned out to be corrosion on my battery relocation kit in the engine bay near the front, cusing my injectors to not get full power. but if i were you i would remove the iacv and clean it all up anyways. it couldn't hurt and takes about 2 hours total. that way you know for sure if its even the problem and if not you have a nice clean guaranteed working part anyways.

zrs6v4 · 04-15-2012, 03:03 PM

Well I just cleaned the iacv and on s14 sr motors its right on top of the intake mani (3 10mm bolts). I cleaned it with throttle cleaner really good and it didnt change anything.

I actually just relocated the battery to the trunk a week ago. The issue was before o did that and is still ocurring. I basically kept the grounds the same on the engine, re-ground the battery in the trunk and stretched the positive cable (2 gauge) to the trunk.

Windycity: are you suggesting I clean up and redo grounds?

I also assume the iacv can have a bad selenoid or be wired wrong?

jr_ss · 04-15-2012, 03:38 PM

Try unplugging the MAF at idle and see if it changes anything...

zrs6v4 · 04-15-2012, 07:09 PM

Quote:

Originally Posted by jr_ss

Try unplugging the MAF at idle and see if it changes anything...

Yea it did make a difference.

I just thought it was unique that unplugging the IACV vacuum would cause the car to run perfect and with it plugged in it runs badly.

I assume there is an issue with the plunger or the electrical of the IACV since I cleaned it out and it made no difference.

I wonder if it stays closed with vacuum and without vacuum stays open?

jr_ss · 04-15-2012, 07:38 PM

The IACV allows enough air to bypass the throttle plate to allow it to idle at the given speed. Tighten the screw idle drops down, open it up and idle increases. I think the MAF is your problem considering you have issues up into the 3k rpm range and an IACV does nothing for you up there...

zrs6v4 · 04-15-2012, 07:49 PM

Quote:

Originally Posted by jr_ss

The IACV allows enough air to bypass the throttle plate to allow it to idle at the given speed. Tighten the screw idle drops down, open it up and idle increases. I think the MAF is your problem considering you have issues up into the 3k rpm range and an IACV does nothing for you up there...

Yea I did notice that when I pull the maf plug the car will die. Im just not sure how to check maf I guess. I will do some tinkering tomorrow.

jr_ss · 04-16-2012, 05:34 AM

The fsm is your friend, download it.

04-15-2012, 01:02 AM	#1
zrs6v4 Join Date: Aug 2007 Location: St. Louis, MO Posts: 29 Trader Rating: (0) Feedback Score: 0 reviews	S14 sr20 weird IACV issue advice I have a 95 240sx with s14 sr swap. Its clean but has been running rough from idle to about 3500 rpms. When cruising at 3,000 rpms it cuts out a bit. I believe I have it to the iacv, but maybe you can chime in. I pulled the iacv vacuum hose out of my intercooler piping so the iacv would not get vacuum or whatever. With the vacuum to the iacv off the car runs perfect except dies if i dont keep reving it when stopped but with the iacv vacuum on it runs terrible. Ive never had an iacv issue so im not sure if i need to just clean it or if i needed to replace it. Any advice?

04-15-2012, 03:38 PM	#4
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,052 Trader Rating: (34) Feedback Score: 34 reviews	Try unplugging the MAF at idle and see if it changes anything... __________________ My SR20VET

04-15-2012, 07:38 PM	#6
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,052 Trader Rating: (34) Feedback Score: 34 reviews	The IACV allows enough air to bypass the throttle plate to allow it to idle at the given speed. Tighten the screw idle drops down, open it up and idle increases. I think the MAF is your problem considering you have issues up into the 3k rpm range and an IACV does nothing for you up there... __________________ My SR20VET

04-16-2012, 05:34 AM	#8
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,052 Trader Rating: (34) Feedback Score: 34 reviews	The fsm is your friend, download it. __________________ My SR20VET

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04-15-2012, 02:40 PM	#2
WindyCity Zilvia Junkie Join Date: Jul 2010 Location: C H I C A G O Posts: 526 Trader Rating: (2) Feedback Score: 2 reviews	i had a similar problem to this. it turned out to be corrosion on my battery relocation kit in the engine bay near the front, cusing my injectors to not get full power. but if i were you i would remove the iacv and clean it all up anyways. it couldn't hurt and takes about 2 hours total. that way you know for sure if its even the problem and if not you have a nice clean guaranteed working part anyways.

04-15-2012, 03:03 PM	#3
zrs6v4 Join Date: Aug 2007 Location: St. Louis, MO Posts: 29 Trader Rating: (0) Feedback Score: 0 reviews	Well I just cleaned the iacv and on s14 sr motors its right on top of the intake mani (3 10mm bolts). I cleaned it with throttle cleaner really good and it didnt change anything. I actually just relocated the battery to the trunk a week ago. The issue was before o did that and is still ocurring. I basically kept the grounds the same on the engine, re-ground the battery in the trunk and stretched the positive cable (2 gauge) to the trunk. Windycity: are you suggesting I clean up and redo grounds? I also assume the iacv can have a bad selenoid or be wired wrong?