Stumble at deceleration, sometimes stalling out

[pgt892]

Ok, well my SR is performing great except for one minor issue. When I put the car into neutral the car stumbles, the RPMs drop down to 100-500 and sometimes stalls out. My boost gauge reads vacuum at 15 which from what I understand is irregular. So my question is, could the stumbling during deceleration be a vacuum leak, and if so what is the most probable cause. I checked all of my vacuum lines on the throttle body and they were fine. Are there any other lines I should look at. The problem isn't life threatening, albeit it is rather annoying. Thanks in advance for the help.

[The Mic]

Check your IAA Valve. To adjust it, read the following:

The IAA valve assembly is located on the passenger side of the motor downbelow and behind the intake manifold. It's about 8" from the firewall.According to the Nissan shop manual, to adjust the IAA valve, disconnectthe throttle sensor harness connector with the motor shut off. Now with theengine idling in neutral, adjust the IAA for an idle speed of 650 RPM. Withthe motor shut off, reconnect the harness connector. Now with the motoridling, you should have an idle speed of 700 RPM. If you can't get theproper idle speed, the AAC valve may be defective as It's the one thatreceives signals from the ECU. The AAC bolts on to the IAA.

[pgt892]

Ok, I will try that out tomorrow. Does that have anything to do with the screw between the runners of the intake manifold?

[pgt892]

OK. I adjusted the idle as per FSM guidelines. I took the TPS off, adjusted the idle to 750RPMs with the IACV screw. After turning off the motor and plugging the TPS in, the idle went up to around 800RPMs. So far so good, however, after driving the car, the RPMs still fall to 250-500 sometimes stalling out when I push in the clutch/shift the car to neutral. Do I need to take off my upper intake manifold and take the IACV off and clean it, or does it sound like a vaccuum leak? If I take my foot off the brake, the idle will increase to normal 750RPMs. My vaccuum gauge only reads 15 inHg @ idle. Driving around, hoping that my car doesn't stall out is maddening. Thanks in advance for any help.

[Nismo_Freak]

Are you running a BOV and is it venting to atmosphere?

You should clean your IACV.

[pgt892]

I am running the stock sidemount with the stock recirc-valve. I checked it, it is recirculating.

[vlow1210]

i had the same problem with my s14 sr..

adjusted the iacv to raise idle. it was cool, although my idle was a bit high, around 950 or so.

then i got a bov and didn't recirculate it... problem came back.

recirculated it, now it's fine although it still drops to around 500rpms sometimes on decel, but doesn't get close to stalling. it's ok most of the time

[Projex240]

15 psi at idle still isnt good. It needs to eb at 20

[pgt892]

I thought that 15 inHg seemed a little low. I have checked all the vaccuum lines and I don't see any leaking. I don't know where else to look for vaccuum leaks.

[chillmieste]

my car does the same thing. The car drives fine but its rather annoying. it sucks because i have to keep revving the car until idle catches again. ill try what s13 guy said to do though.

[pgt892]

Just a little added info, which I find quite strange. Like I said, my standard idle is 15 inHg in first gear. However, sometimes when I shift into first, say at a stop light, my RPMs will drop, my vaccuum will move to 11-12 inHg and if I let off my brake, my car will move forward quickly. Generally, when I let my foot off the brake in first the car will only move forward a little bit if at all. I don't know how this is related or what it could be, but it is more information.

[pgt892]

I pulled a code from the ECU and it is saying 11 which is CAS. I didn't think I had a problem with my CAS, now I am just confused.

[chickentendah]

Bad timing can give you bad vaccum----which is probably the last thing on anybody's mind.

[pgt892]

I pulled the plug off my CAS and part of the plastic housing is broken/chipped. It is the plastic part that the plug goes over, not the circular main piece.

[llamabeta]

Given your mechanical timing is correct. Perhaps, a reset of the CAS would help?

http://www.store.yahoo.com/pha....html

Of course, your CAS has to be working properly.

I am in the same boat right now. Going to pull the IACV off and clean it out whenever I get off my lazy butt.

[Projex240]

screw the CAS--you dont need it. Ive been running without one for 2 years. Even nissan said its worthless.

-Josh

[pgt892]

Well I cleaned the IACV without taking off the intake manifold and it has helped a ton. What I did was let the car come to a normal idle, took of the tube from the cold pipe to the IACV and sprayed some cleaner down the tube while increasing the throttle to keep the car from dying. I did this three times in the course of two days and after each time I would drive the car to remove any deposits as per the instructions on the can. The stuff I used was Amsoil Power Foam, but I assume any throttle body/intake manifold cleaner would work. This helped my problems when I would push in the clutch by a lot. I still am having problems with shifting, but I think that is related more to my slave cylinder which I will be replacing. Thanks for everyones input.

[llamabeta]

Excellent. Good to hear. I shall give this a try.