High Idle/ Stalling

[SunnyTK]

I jsut bought a 89 Pathfinder Automatic. It has 163,000KM on it, everything is original I belive (there is signs of a recent tune-up though). is that it has a high and fluxuating idle, between 1500 and 2500rpms. And if I put it in drive before its fully warmed up, it stalls. I think there is a vacuum leak coming from the front top of the manifold, but I cant hear or see exactly where its coming from. I just hear a whistleing sound kinda.

 

I did google search a vacuum diagram for the vg30i, but it was kinda hard to read compared to my actual engine.

 

Would anybody be able to help me?

 

edit: this is the one i was referencing to

[MY1PATH]

If you used a stethascope It may help you locate the leak. Or you could replace all the vaccum lines being as they are prolly about 20old. I'll be doing that to mine one day, just preventative measure.

[Nismojunky]

to narrow down your serch for the leak, (if it idles steaddly when shes warm) get a torch and rus the gas around your vacume lines if theres a leak the idle with change massively because it will suck the gas in and burn it

[SunnyTK]

I remember reading somewhere about spraying WD40? but I have a pretty acurate idea of where the leak is coming from (if theres a leak), but I just cannot see exactly where its coming from

[Precise1]

I remember reading somewhere about spraying WD40?

Yes, this is what I recommend... First verify there is a leak, if you can't 'find' it, pull the line and inspect/replace it. Repeat until repaired.

 

B

[BowTied]

WD40 or carb cleaner or other sovent based aerosols will work, note that these are flammable and can ignite on hot surfaces like exhaust manifold. I think there is less chance of this with or acetelyne, propane gas (but certainly propane or acetylene needs to be handled with appropriate safety measures).

 

the stethascope idea - a long length of ruber tuning will work for this.

 

Often inspection of old hoses finds the problem as noted.

[BowTied]

One way is to visually inspect all the vacuum hoses and connections. Look for disconnected, loose or cracked hoses, broken fittings, etc. Hey, you might get lucky and find the problem in a few minutes, or you might waste half the day trying to find the mysterious leak. Vacuum leaks are often the elusive needle in a haystack. And if it is not a hose leaking vacuum but something else such as a gasket, worn throttle shaft, injector O-rings, etc., you may never find it using this technique. A faster technique for finding intake manifold vacuum leaks is to get a bottle of propane and attach a length of rubber hose to the gas valve. Open the valve so you have a steady flow of gas. Then hold the hose near suspected leak points while the engine is idling. If there is a leak, propane will be siphoned in through the leak. The resulting "correction" in the engine's air/fuel ratio should cause a noticeable change in idle speed and/or smoothness (Note: on engines with computerized idle speed control, disconnect the idle speed control motor first).

 

Aerosol carburetor cleaner can also be used the same way. CAUTION: Solvent is extremely flammable, so do not smoke or use it if there are any sparks in the vicinity (arcing plug wires, for example). Spray the solvent on suspected leak points while the engine is idling. If there is a leak, the solvent will be drawn into the engine and have the same effect as the propane. The idle speed will suddenly change and smooth out.

 

TIP: If you have a scan tool, look at the Short Term Fuel Trim (STFT) value while you are using carb cleaner or propane to check suspected vacuum leak points. If there is a leak and some of the cleaner or propane is sucked in through the leak, you will see a momentary drop in the STFT reading. This confirms you have found a leak (keep checking because there may be multiple leaks!).

 

from http://www.aa1car.com/library/vacleak.htm

[SunnyTK]

K, I sprayed WD40 around the manifold... and nothing changed and no flames.

 

I did notice a disconected vacuum line of some sort behind the motor, on the fire wall... it lead to a round device in the corner...

 

soo I asked my brother what he thought it might be, and he siad it my be my stall/idle controller? i was looking for it, but i didnt know where it was

[Alkorahil]

Your borther is correct. Could be bad IACV-ACC Valve and/or regulator. Only one way to find out really though and thats replace which is a half day project. It is located on the back driver side of the engine near the firewall. The cone shaped part back there pointing up is the regulator, underneath is the valve.

 

 

 

loose wire/connector at the MAF.