Stumbles off boost, low RPM, idles fine, boosts fine - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

AuburnRyan · 03-08-2006, 08:58 AM

Hey all,

s13 SR with FMIC, HKS SSQV, Walboro HKS Actuator, etc. etc.

Car boosts great to 14psi, and idles fine around 1000 RPM.

Car has developed hiccups, stumbles, or bogs briefly when I'm cruising off boost (usually around -10 vac). The vaccum seems to *sometimes* jump when this happens, but it's a quick hiccup when I'm cruising.

First thing I'm thinking is vaccum leak. I just glanced over the lines which look snug.
I recently repaced spark plugs a few weeks ago.
Could my walboro be going out?

Any other ideas?

AuburnRyan · 03-08-2006, 12:36 PM

*cough*

Is this and odd issue that the problem only occurs off boost?

the head · 03-08-2006, 01:13 PM

check all piping for leaks I would guess that is your issue, that or the BOV is leaking if all else fails recirc your BOV

Gearhead_42 · 03-08-2006, 01:42 PM

Quote:

Originally Posted by the head

that or the BOV is leaking if all else fails recirc your BOV

I understand (have no personal experience with this) that a free air BOV can cause this kind of stumble. I'm assuming the SSQV is not recirculated? Basically, MAF is telling the car there's more air than is actually getting in, causing a rich condition. Leaking FMIC piping could also be to blame.

And yes, I know I just restated you guys

Dan

AuburnRyan · 03-08-2006, 01:59 PM

I'll tighten the BOV to check, and yes it's open...but I'm talking about a stumble when I'm not boosting, so the BOV shouldn't come into play, right?

It' feels as if the fuel gets cuts for a half second. Like there is air bubbles or something...a quick hiccup, and that's it.

03-08-2006, 08:58 AM	#1
AuburnRyan Zilvia Member Join Date: Aug 2002 Location: Northern VA Posts: 272 Trader Rating: (0) Feedback Score: 0 reviews	Stumbles off boost, low RPM, idles fine, boosts fine Hey all, s13 SR with FMIC, HKS SSQV, Walboro HKS Actuator, etc. etc. Car boosts great to 14psi, and idles fine around 1000 RPM. Car has developed hiccups, stumbles, or bogs briefly when I'm cruising off boost (usually around -10 vac). The vaccum seems to sometimes jump when this happens, but it's a quick hiccup when I'm cruising. First thing I'm thinking is vaccum leak. I just glanced over the lines which look snug. I recently repaced spark plugs a few weeks ago. Could my walboro be going out? Any other ideas? __________________ '93 Fastback LE - Wrecked '91 Fastback HICAS and LSD - Sold '93 Fastback SE - Current

03-08-2006, 12:36 PM	#2
AuburnRyan Zilvia Member Join Date: Aug 2002 Location: Northern VA Posts: 272 Trader Rating: (0) Feedback Score: 0 reviews	cough Is this and odd issue that the problem only occurs off boost? __________________ '93 Fastback LE - Wrecked '91 Fastback HICAS and LSD - Sold '93 Fastback SE - Current

03-08-2006, 01:13 PM	#3
the head Nissanaholic! Join Date: Jul 2002 Location: in a dark room mastering the art of typing with one hand Posts: 2,164 Trader Rating: (3) Feedback Score: 3 reviews	check all piping for leaks I would guess that is your issue, that or the BOV is leaking if all else fails recirc your BOV __________________ I never knew you could do that with an eggplant

03-08-2006, 01:59 PM	#5
AuburnRyan Zilvia Member Join Date: Aug 2002 Location: Northern VA Posts: 272 Trader Rating: (0) Feedback Score: 0 reviews	I'll tighten the BOV to check, and yes it's open...but I'm talking about a stumble when I'm not boosting, so the BOV shouldn't come into play, right? It' feels as if the fuel gets cuts for a half second. Like there is air bubbles or something...a quick hiccup, and that's it. __________________ '93 Fastback LE - Wrecked '91 Fastback HICAS and LSD - Sold '93 Fastback SE - Current