Dirty aac valve? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Josho · 08-29-2011, 08:02 AM

My sr is doing the strangest thing. Last night I started her up and it was idleing up and down, trying to cut off until i gave it a little gas. When it warmed up a little it would stay running by itself but would jump to 1200 rpms and fall to abt 4-500 and jump back up. When I would rev it to about 4000 and let the rpms fall back down, it always would cut off. I noticed that, while revving it up, it wouldnt bog or anything, it revved as far as i wanted it to freely. My temporary fix was turning up the idle to about 1100rpms. I also Noticed that when the fuel pump was priming(255 fp) it didnt have a constant hmmmmmmmmmmm.. It is more like hmm hm hmmm m m hmmm m..
But now that I have the idle turned up everything seems to be fine, I can drive it around without it hesitating or trying to cut off.
I need to fix the problem regaurdless though. Just needed some opinions I guess. Does it sound more like the aac valve needs to be cleaned or a fuel pump replaced.. Or both? I just ordered a new 255 because mine sounds weak anyway.

FYI: I checked for boost leaks, cleaned and re-gapped plugs, and cleaned out my maf. This was all before I turned up the idle.

KiLLeR2001 · 08-29-2011, 09:08 AM

Check for vacuum leaks. Inspect all your vacuum hoses for small cracks. Fuel pump might be on its way out. You change the fuel filter recently? Also make sure all your grounds are good and you don't have any electrical fans powering off your fuel pump circuit.

Josho · 08-29-2011, 12:17 PM

I forgot to mention that I also got a new z32 fuel filter.

08-29-2011, 08:02 AM	#1
Josho Zilvia Junkie Join Date: Mar 2010 Location: AL Posts: 310 Trader Rating: (7) Feedback Score: 7 reviews	Dirty aac valve? My sr is doing the strangest thing. Last night I started her up and it was idleing up and down, trying to cut off until i gave it a little gas. When it warmed up a little it would stay running by itself but would jump to 1200 rpms and fall to abt 4-500 and jump back up. When I would rev it to about 4000 and let the rpms fall back down, it always would cut off. I noticed that, while revving it up, it wouldnt bog or anything, it revved as far as i wanted it to freely. My temporary fix was turning up the idle to about 1100rpms. I also Noticed that when the fuel pump was priming(255 fp) it didnt have a constant hmmmmmmmmmmm.. It is more like hmm hm hmmm m m hmmm m.. But now that I have the idle turned up everything seems to be fine, I can drive it around without it hesitating or trying to cut off. I need to fix the problem regaurdless though. Just needed some opinions I guess. Does it sound more like the aac valve needs to be cleaned or a fuel pump replaced.. Or both? I just ordered a new 255 because mine sounds weak anyway. FYI: I checked for boost leaks, cleaned and re-gapped plugs, and cleaned out my maf. This was all before I turned up the idle.

08-29-2011, 09:08 AM	#2
KiLLeR2001 Post Whore! Join Date: Jun 2007 Location: オーランドフロリダ Posts: 7,955 Trader Rating: (46) Feedback Score: 46 reviews	Check for vacuum leaks. Inspect all your vacuum hoses for small cracks. Fuel pump might be on its way out. You change the fuel filter recently? Also make sure all your grounds are good and you don't have any electrical fans powering off your fuel pump circuit. __________________

08-29-2011, 12:17 PM	#3
Josho Zilvia Junkie Join Date: Mar 2010 Location: AL Posts: 310 Trader Rating: (7) Feedback Score: 7 reviews	I forgot to mention that I also got a new z32 fuel filter.