3.4 wont stay idle. Instantly dies

[Aciddrag0n1]

Recap:
This morning got in my car, started up just fine drove it about 200 yards and realized I left something at home. Turned around, went back and shut my car off to get back in my place. I go to try and start it again, it starts up then immediately dies. Start it up again and the same thing. Now from here on out it will barely start up at all. I have to give it gas for it to even turn over, but it wont crank up enough to even idle.

Bad gas, fuel pump, fuel filter, injectors, control modulator, O2 sensor, etc? Anyone got some advice where to start?

[tkoforpresident]

Re: 3.4 wont stay idle. Instantly dies

getting any engine lights?

and first thing i'd check would be fuel pressure. (there is a capped valve on the fuel rail in the middle of the intake plenum valley) that could save a lot of time/trouble.

[Aciddrag0n1]

Re: 3.4 wont stay idle. Instantly dies

No engine lights. Too cold outside to work on right now. But yes, i'll be checking the pressure... could you give any better description where that is? Lost my Haynes Manual.

[tkoforpresident]

Re: 3.4 wont stay idle. Instantly dies

if you look at the intake manifold, right in the center is the fuel rail. at the very front of the fuel rail is a capped valve. just unscrew the cap and then you have a point where you can check your pressure.

[Aciddrag0n1]

Re: 3.4 wont stay idle. Instantly dies

I have pressure. I also used the screw driver method and tested all the spark wires. All gave good spark. Any other suggestions?

[viper98885]

Re: 3.4 wont stay idle. Instantly dies

Idle Air Control (IAC) valve. This is on the side of the throttle body. It can get gummed up with carbon deposits and the pintle cannot move in and out properly. You can remove it (2 torx screws holding it on) and clean it with throttle body cleaner. Don't forget to clean down into the cavity on the TB where the pintle goes too. It could also be that the IAC is bad. They are not too expensive if that is the case.

[tkoforpresident]

Re: 3.4 wont stay idle. Instantly dies

well of course you have pressure.

but what was the psi rating?

there are specific psi ratings that you should fall into during idle/key on etc.

[Aciddrag0n1]

Re: 3.4 wont stay idle. Instantly dies

45psi on key turn over. ive cleaned out the IAC. Still no go. CPS?

[tkoforpresident]

Re: 3.4 wont stay idle. Instantly dies

ok then, thats in range of what it aught to be. good news! you can rule out the fuel pump =p

what is the CPS? you mean the TPS? (throttle position sensor)

[viper98885]

Re: 3.4 wont stay idle. Instantly dies

CPS = camshaft position sensor or crankshaft position sensor.

[blackandgold]

Re: 3.4 wont stay idle. Instantly dies

On my 3.4 after you unplug the batter for a long period of time, you have to sit there and hold the gas to keep the rpms at like 2000 or so for a couple minutes, I think it has to do with resetting the pcm or something, or maybe my 15 year old car just has some quirks.

[tkoforpresident]

Re: 3.4 wont stay idle. Instantly dies

CPS = camshaft position sensor or crankshaft position sensor.

ah thats right. Wasn't registering in my head.

Crank position sensor is actually a very good guess, that is the 3x sensor and not the 24x sensor. the 3x when bad will give you a VERY hard time to get running while when the 24x sensor goes bad it is not much of an issue (usually just takes an extra second or two to start)

Neither are fun to replace but the 3x is considerably easier when you take into account that you don't have to remove the harmonic balancer, however it is a very tight fit being that its triangulated somewhere between the starter, exhaust manifold and the block (well actually its sticking into the block) on the passenger side of the motor.

Camshaft position sensor... that wouldn't have any effect at all with the start up. It's only use is the higher rpms for SFI to eake out another mpg or two.

I'd say give the 3x sensor a shot

[Mighty Thor]

Re: 3.4 wont stay idle. Instantly dies

CPS = camshaft position sensor or crankshaft position sensor.

Yes, this happened to my bro's nissan altima too. Exactly the way you describe it. But his did throw a code and it came out to be CPS.

Changing this on the fbody is easy. But on an altima, it took me forever.