05 suddenly won't run. Ideas? +02 Sensor

I stopped for gas tonight. After fueling up I was pulling away when the car stuttered and died. It's never acted unhealthy until now. I started her back up, it idled normally but when I started to pull away it started shuddering, revs dropping and it died.

I rolled out of the way into a parking lot, where it is now. I tried starting it several times:

First few times: started right up and idled healthily, but car makes no response to the gas pedal (ECU wasn't opening throttle plate when I requested more torque). After ~5 seconds it would start to shudder, the revs would drop to 500pm for a bit and then die.

Now: Idles for a second or two stuttering <500rpm then dies.

I'm not sure if the two are related:

For the past several weeks I've had a check engine light. It was reading P0134. Front O2 Sensor low. The car ran pretty well though, maybe twice a week I would notice a single shudder at idle. When it first came on I did a pull and didn't any log knock so it was low priority.

I brought my laptop over there and now I have P0031 also, no activity front 02 sensor

So ...

Could it be just the front o2 sensor? I could easily do that in the parking lot. Could it be the fuel pump? It seems like it to me, but I was hoping there would be some error codes to suggest it. The only two codes are:

DTC MEMORIZED: P0031 FRONT O2 SENSOR LOW INPUT

DTC MEMORIZED: P0134 FRONT O2 SENSOR NO ACTIVITY

Any ideas are *greatly* appreciated, I need to get her back on the road ASAP. Poor Outback

Replace your front O2 Sensor. It's easy to do even in a parking lot. Then see if it works. Get a genuine one from your local dealership.

I feel like my little dog could have figured this one out, and I also suspect you already knew the answer because you told it in your post. GL

But the car went from running to suddenly not running at all. It got worse each time I started it.

The dealership is closed today. Is it vital I use a genuine one?

It is quite important to use a Subaru one.

The front O2 sensor is the business sensor. All of closed-loop fueling demands that sensor work as the ECU thinks it will.

An O2 sensor is not going to stop your car from running.

I would lean towards the fuel pump. A car will idle with very little fuel pressure or flow but as soon as you put any demand on the pump (trying to drive) it will not be able to keep up.

unplug the maf sensor. if the car runs relatively fine, it's not a major mechanical problem

Is this a joke or will it use preset maps independent of the o2 sensor?

A closed loop map will only adjust for an O2 sensor reading so far. There is a limit to short term and long term corrections. An O2 sensor will not prevent you from driving your car... it may not run perfectly but it will still be drivable.

Unplugging your MAF can rule out popped IC pipes or disconnected intake hoses.

The way your car went from running fine to not running at all tells you things. You probably did not pop an IC pipe off or disconnect the intake tube while refueling.

Is your car modified? Do you have an aftermarket fuel pump?

I have the original fuel pump. Mods:

Forge bypass valve (March 2010)

EL headers (January 2010)

Up-pipe (January 2010)

Apart from that are just the flywheel and brakes which wouldn't matter and weren't recent.

I wish there were more DTCs. There aren't even temporary misfires. It sure is acting like a piece of equipment that just ran out of gas. Any safe (for the pump) and easy ways to test the fuel pump? Is there a schrader valve in the fuel line anywhere?

Recirculating. Thanks for the idea

I just had it towed. This morning it wouldn't start, kicked a tiny bit but not close to catching.

The tow truck driver was the one trying to start it and right away he said it's the timing belt. He said it probably has teeth missing and the cams have skipped on it. He was pretty darn certain. I was pretty darn pissed.

The car has 67500 miles. Original timing belt.

Now it's at my place and I can fool around with it. For starters I'm going to see what romraider says the fuel pressure is. And check that dump valve, and any other vacuum leaks.

I have never seen missing teeth on a timing belt. Skipping timing can happen and can cause a no start issue but the way your car reacted it is not likely. You said it would idle fine at the gas station till you tried to take off. This would indicate the cam timing is fine.

It still sounds like fuel pressure issues to me.

On RomRaider with the key at the On position I'm not reading anything for fuel pump duty cycle and fuel tank pressure is 0.09psi. Is this normal? I would think that the fuel pump would be running with the key on. I was also hoping there would be like a fuel rail pressure, but with the return would the pressure on the tank be the same as the rail?

Do those figures in RomRaider actually mean anything?

Is there a fuse or relay for the pump? I really don't understand that the fuel pump duty cycle is 0.00 with the key on, is that what the ECU is sending to the pump or is that what the pump is actually doing? Or would I need to be cranking?

For starters I'm going to see what romraider says the fuel pressure is.

That might be difficult...

But the car went from running to suddenly not running at all. It got worse each time I started it.

Sounds just like fuel pressure bleeding off as it runs.

Is there a fuse for the fuel pump?

Did you ever unplug the MAF? If not - DO IT. A major leak in the intake will cause the car to not idle because it's relying on the (wrong) inputs from the MAF. If you unplug it, the ECU removes MAF from the equation and the car runs pretty well.

Use this to drive if you need to get the car to a location where you can work on it. It isn't going to hurt anything. Obviously you shouldn't boost or anything but normal driving is easy. This same trick has worked on MAF-equipped cars for 20+ years.

There is a fuel pump fuse under the hood, and it's labeled under the fuse box plastic cover.

Fuel pressure (at least the 43.5psi +/- kind) only exists between the fuel pump and the fuel pressure regulator. You would need to T in a fuel pressure gauge in one of your fuel lines to get what you're looking for.

Fuel pump only primes when you turn key to ON/IGN. Doesn't continue running until you start it up.

Swapping on your stock BPV will rule out the Forge as a problem.

A genuine Subaru O2 is recommended because wiring up an aftermarket (cheaper) one is very hit-or-miss, and you would have no easy way of figuring out if you did it right. It might benefit you to change the sensor that your car has been saying has been off for weeks and is now dead. They do have the ability to fail, as this forum has indicated many times. You can replace it by jacking up the front passenger corner, and then using an O2 socket with a LONG extension to reach it from outside the wheel well. Or do it closer if you want, but either way it's easy to do, and you have nothing to lose except you will end your skating around the issue of it throwing codes.

Sounds just like fuel pressure bleeding off as it runs.

 

Is there a fuse for the fuel pump?

I agree. I checked the fuse for the fuel pump; it looked fine. I went ahead and replaced it anyway but it's still acting the same. The car doesn't start anymore just turns over, but it pauses or slows down for the slightest bit when it would normally kick.

Any suggestions on how to check the pump? Like I asked before: is there a schrader valve anywhere? I don't have a spin-on gauge or anything but I was thinking I could just depress the valve and see if there's pressure and if it comes back

As for the o2 sensor, I did some reading on it and got the correct part # and no one in town has it so I'll have to buy one from the dealer tomorrow. I don't think it's my issue, though. I'm going to go outside and try the MAF trick

Update: No luck on the MAF trick. I turned it over and over and no difference. It didn't act like it was going to start at all. It really is acting like it has no fuel. For kicks I smelt under the hood and at the tail pipes and there wasn't a gas smell, though I don't know if there would be

Side note: dang. My tail pipes are really sooty. They weren't battle-ship grey when I got the car but they sure weren't covered like a chimney. I must have been running pretty rich with the o2 sensor going. I should probably think about replacing that cat down the line

I checked all the intake hoses; they all look very healthy and each vacuum line seemed to be in place. I assume that with the MAF trick it still should have ran regardless of if the forge recirc valve is sticking or not?

On RomRaider with the key at the On position I'm not reading anything for fuel pump duty cycle and fuel tank pressure is 0.09psi. Is this normal? I would think that the fuel pump would be running with the key on. I was also hoping there would be like a fuel rail pressure, but with the return would the pressure on the tank be the same as the rail?

 

Do those figures in RomRaider actually mean anything?

 

Is there a fuse or relay for the pump? I really don't understand that the fuel pump duty cycle is 0.00 with the key on, is that what the ECU is sending to the pump or is that what the pump is actually doing? Or would I need to be cranking?

I am unfamiliar with RomRaider. I would assume that duty cycle refers to the injector duty cycle. This would be zero with the car not running. Fuel tank pressure is monitored to make sure your evap system is working.

The fuel pump will usually not run with the key in the ON position unless the car is running. Most cars will prime the fuel system when you turn the key by running the pump for a few seconds though.

I think the only way to determine fuel pressure is going to be with a gauge T'd into the fuel feed line.

It might benefit you to change the sensor that your car has been saying has been off for weeks and is now dead. .

A failing fuel pump can also cause the codes. If pressure was slowly dropping over time, the ECU would compensate by adding extra injector pulse width. Once the limits of long term and short term corrections were maxed out, you would start getting a slow response at the O2 sensor due to the inability to compensate. Eventually no response.....

I am not saying this is what happened but if it were me, I would hold off on the O2 sensor till I got the car running again and could evaluate it properly.

What do you guys think of what the tow truck driver said about the timing belt? He was also trying to get me to bring the car to his shop and not my house, so his intentions are a little suspect from the beginning.

Isn't there a way to drain the fuel lines? When you are going to replace the fuel pump, don't you release pressure first somehow? I would think so. I'm looking at the diagrams in the shop manual and am not really seeing anything, unfortunately.

There's a two-way valve drain hose. I'm not sure what a two way valve (20 on the diagram) is. Ideas?

I agree. I checked the fuse for the fuel pump; it looked fine. I went ahead and replaced it anyway but it's still acting the same.

You are also going to have a fuel pump relay. It may be #25 relay in the main fuse box (under the hood) based on what I found on the net. Find an identical relay in the fuse box to swap it out with and see if that helps.

You are also going to have a fuel pump relay. It may be #25 relay in the main fuse box (under the hood) based on what I found on the net. Find an identical relay in the fuse box to swap it out with and see if that helps.

Did you see where they say it is? According to my shop manual it's behind the glove box.

By the way, thanks guys for the help so far http://legacygt.com/forums/images/icons/icon14.gif. I really do appreciate it

What do you guys think of what the tow truck driver said about the timing belt? He was also trying to get me to bring the car to his shop and not my house, so his intentions are a little suspect from the beginning.

 

Isn't there a way to drain the fuel lines? When you are going to replace the fuel pump, don't you release pressure first somehow? I would think so. I'm looking at the diagrams in the shop manual and am not really seeing anything, unfortunately.

 

There's a two-way valve drain hose. I'm not sure what a two way valve (20 on the diagram) is. Ideas?

I do not agree with the tow truck driver.

To relieve pressure from the rails, you pull the fuel pump fuse and keep starting the car till it no longer starts.

#20 on the diagram is part of the evap system.