[dharmashiv]

1998 Subaru Forester 4 cyl All Wheel Drive Manual 205000 KM

The car was unused for about 4 weeks. Upon driving it again, it began to stall at random, typically once in a 50 KM trip. The engine slows and seems to lack power. When you put your foot on the gas, the engine balks then dies. Turning off the ignition and restarting is fine. The engine then runs smoothly and I am able to continue driving until it stalls again 5 to 15 minutes later.

The initial engine code was 0304. I R and R'ed that plug but the problem persisted. Since the symptoms appaered fuel system related I have done a number of things diagnosticly and replaced parts.

-new fuel filter: no change
-new fuel pump: no change

There is no smell of gas. The fuel pressure regulator is behaving normally. Fuel system pressure is within tolerences. No codes are shown when the reader is attached when driving.The car starts fine and idles smoothly and at the correct RPM even after warm up.

Similar issue to:

Giessens, subaruforester.org/vbulletin/f88/1998-forester-randomly-dies-while-driving-down-road-68501/

but no codes shown on the ECU

Argh!

 

[TexasForester]

Spark plug lead to that cylinder may be weak. I had this happen and replaced entire spark plug lead set. Problem was broken wire at top of the plug connector. They get pulled quite hard to remove sometimes and stress/time eventually get them.

You may be able to swap wires first to see if problem follows the current #4 cylinder wire to a new cylinder or stays w/ the #4 cylinder indicating a fuel delivery, air delivery, or valve leak on #4.

good luck

 

[dharmashiv]

No luck yet

As I said, the fault code doesn't materialize any more and the engine runs smoothly.....until it doesn't. There is no mis-fire on cylinder 4.

I have tried a number of things today.

1. checked connection to MAF due to code 0102. All OK.
2. Checked connections to Pressure Sensor due to code 01006. All OK. ( not sure why it's on the car since the Haynes manual says it's only on cars with auto trans and/ or turbos)
3. checked wiring harnes to ECU. Clean and tight. No water at all.

I am leaning towards a fault with the fuel pump relay, since the stall doesn't net any codes from the ECU. There are three relays that all look the same under the steering column, to the left and the manual doesn't show what I have, so it is a hunch.

When the stall occurs, the ignition has to be shut off in order for a re-start to occur, as though you are re-booting the ECU.

Any other thoughts?

 

[flstffxe]

...
When the stall occurs, the ignition has to be shut off in order for a re-start to occur, as though you are re-booting the ECU.

Any other thoughts?

This should actually help to track it down. Drive it around and get it to stall in a convenient spot. Then you can at least narrow it down to a fuel or spark issue.

- Bring a spare spark plug with to verify spark. Pull a plug wire off put the spare plug in it then proceed to crank the engine and check for spark. If you have spark move on to the next item. If not check all the connections for the coil, cam, crank position sensors. If that is all good it may be a faulty cam or crank position sensor.


- Listen for the fuel pump to prime when trying to start it, Plumb in a fuel pressure gauge at the fuel filter OR pull the fuel line at the fuel filter and feed it into a container to verify the pump works.

Doing the above will at least give you a solid direction to go.

 

[dharmashiv]

Been there, done that, have the barked knuckles to show......

This should actually help to track it down. Drive it around and get it to stall in a convenient spot. Then you can at least narrow it down to a fuel or spark issue.

- Bring a spare spark plug with to verify spark. Pull a plug wire off put the spare plug in it then proceed to crank the engine and check for spark. If you have spark move on to the next item. If not check all the connections for the coil, cam, crank position sensors. If that is all good it may be a faulty cam or crank position sensor.


- Listen for the fuel pump to prime when trying to start it, Plumb in a fuel pressure gauge at the fuel filter OR pull the fuel line at the fuel filter and feed it into a container to verify the pump works.

Doing the above will at least give you a solid direction to go.

1. No issue with spark.
2. Checked and verified connections. Can simulate fault from ECU by leaving them unplugged so not an issue.
3.Fuel pump runs fine. Pressure is 28-32 PSI and rises when FPR vacuum hose is disconnected.

I located and swapped the heater fan relay for the FP relay. Took it for a 10 minute drive and no stall. (yet)

Will update later.

Thanks for the advice so far.

 

[flstffxe]

I would not be surprised if it is a dead/dieing relay, at least they are cheap.

 

[dharmashiv]

So we took a longer drive.....

True to form, it died at about the 5 minute mark and showed code 0102, the MAF sensor, but I think it's a red herring because I cleared the code and it didn't re-appear when the car stalled 5 minutes later......

I think it was trying hard to stall, as there was a bit of engine surging prior to the next stall but it did not stall for the remainder of the drive or surge which took about ten minutes.

To summarise; a twenty minute drive at various speeds including 10 at highway; 2 stalls and then smooth running. She idles at 800 with no mis-fires.

I dunno any more. Poltergeists?

 

[Blue Fox]

I'm thinking MAF to be honest. If you have the car running and unplug the MAF, it'll kill it immediately. The only problem is, there is no definite way to know if it's the MAF, and it's a pricy option to "try".

I've been having some MAF issues lately, and I don't get a check engine light 90% of the time, only every so often. Though, mine hasn't been stalling, just stuttering through the power band and feeling like I'm towing another car at times.

 

[dharmashiv]

I'm thinking MAF to be honest. If you have the car running and unplug the MAF, it'll kill it immediately. The only problem is, there is no definite way to know if it's the MAF, and it's a pricy option to "try".

I've been having some MAF issues lately, and I don't get a check engine light 90% of the time, only every so often. Though, mine hasn't been stalling, just stuttering through the power band and feeling like I'm towing another car at times.

I unplugged the MAF and started the car. It ran quite roughly, though. The ECU coughed up the 0102 code and another MAF related code (can't remember) right away.

I removed the MAF from the air intake and inspected it. It looks fine and in good shape. The connectors were clean and free of corrosion, though I did give them a spray of De-oxit red, to lube and enhance the contacts. Upon reconnection and start up, the codes didn't re-appear after being cleared. The car also ran smooth, so unless it's a totally random MAF fault, I am still leaning toward the relay.

Interestingly enough, the ECU did not spit out a code when the FP relay was out of circuit. I tried to start the car so it should have registered code 0230 but it did not.

 

[dharmashiv]

Update to stalling @ speed

The later symptoms all pointed to a failing fuel pressure regulator, something you would expect a Subaru dealer to stock, but nooooo. 4 Freakin' days later I got it and the relay. A bit of an ordeal to replace since I had to remove the RH fuel rail to get at it due to rusted screws. Still stalls, and may be worse due to new possible air leaks at injector ports. New relay makes no difference either.

The connection to the MAF may be flaky, since the odd 0102 code shows up but I will need to frigg around with the wiring harness a bit first.

Later.

 

[Mister]

I'm going to cast my inconsiquential vote with the MAF. My Forester also started stalling at speed. I cleaned the throttle valve first, but ended up replacing the MAF to fix it. The codes also didn't indicate the MAF, but other things related to stalling out.

 

[flstffxe]

I too at this point would go with a bad MAF. I have seen a few people have so so experiences with aftermarket ones.

 

[dharmashiv]

So, ponder this one........

After replacing the items as mentioned, the car ran rough at idle. Like a POS to be precise. For all that, other than stalling twice before driving 200 yards, she ran well and didn't stall once in a 70 minute drive.

I think that's progress but I will monitor the fuel economy. I have experienced a faulty MAF before. The car runs in a limp home mode which usually means running rich. For those who remember chokes, it's like having it stuck closed. As a consequence, the car gulps fuel so the fuel economy is halved. The exhaust also smells different due to unburned fuel.

So, I suppose with air leakage around the injectors, the mixture might approximate the stoichiometric ratio on two cylinders at least but I think the ECU would or should barf up the codes for a MAF fault at some point......and it doesn't. Not yet anyway.

I will drive it this week and see what happens.

 

[JimmyM]

Inetermittent stalling @wheneve it felt like it!

Hi there,
Was having similar issues re stalling but was throwing no codes.
Finally got a check engine light after months and it was MAF code.
Turned out to be dry solder joints of the circuit board inside MAF where connector pins are soldered to circuit board. Quick reflow with soldering iron problem solved.
This may help others, its a pretty easy operation to take square plastic cover off and reinstall with some black sealant or similar.