Engine Randomly Cuts Out and Stalls

[MorganM]

Fired it up the other morning, let it warm up 2 or 3 minutes, and took off down the road (35-45 MPH city driving). I get to the first stop light and a BAD missfire (all 4 cyl cut at once) but it recovers. Couple miles later it starts really cutting out, coming back, and I feather the throttle to keep it going. Pull into a parking lot and it dies. Restart the car, AT TEMP light flashes 4-5 times, I pull into a parking spot and shut it down. Take a quick look at everything, fire it back up, seems OK at idle and rev'ing up in park so I take off down the road again.

 

Starts cutting out real bad once again and I start working the throttle to try and keep it running but she eventually stalls. Really hard to get her started this time but when it does the AT TEMP light flashes a few times and away I go (on a busy street; gotta stay moving!) She behaved her self the last few miles home.

 

No check engine light. Scanned with cheap ODBII scanner and no codes. Sometimes at idle, in park, she gets that bad missfire (seems like total loss of spark or fuel; I mean all 4 cyls cut) but doesn't stall. Knock sensor was replaced last year. Used CRC MAF cleaner and cleaned the MAF but problem persists. O2 sensor changed almost 2 years ago. She runs real rich; on a cold start you can't miss the smell of fuel from the tail pipe. Mileage is a sad 24 to 26 MPG (mix of highway and city)

 

Any ideas other than standard reply of 'spark plugs and plug wires'? Got that one covered; lets try some real troubleshooting =)

[MorganM]

Did some testing this morning. Seemed fine until it warmed up. This is all in park, usually at idle, I'd sometimes rev it up and stuff just to play around. Didn't drive around 'cuz I didn't wanna get stuck somewhere =P

 

Anyway I've narrowed it down to a grouping wires in a wire harness. On the right side (passenger side, down near the bell housing under the intake plenum there's 3 wire harnesss groupings). If I move one of those groups just right it cuts out and sometimes stalls.

 

The AT TEMP light did NOT flash today. I have an ODBII scanner and there's no codes. The scanner would pull TCU codes if there were any; right? There's no ECU codes.

 

I guess now I gotta narrow down what's in that group of wires that's causing the problem

[MorganM]

Unplugged those wire harnesses and they looked like they had some white crusties up in the terminals. Sprayed them out with electrical contact cleaner, let them dry, and plugged them back in. Problem still persists but now when I wiggle those wires nothing happens... maybe it's not these at all and it was just coincidence before =/

 

Still no codes... I'm at a loss.

[Gloyale]

Year? Model? Engine?

 

 

Excactly how are you determining that "all 4 cylinders" cut out? IF that where the case it would not run. Let's start one thing at a time.

 

I say hook a timing light to spark plug wires, one at a time, and observe what kind of spark pulse you get.

 

If that is all good, then start pulling injectors connections one by one. Each one you pull should produce a noticable effect on the running of the engine. I it doesn;t, then that injector is bad.

[MorganM]

1997 OBS

EJJ22

4EAT

192,000 miles

 

You can tell when it's just one cylinder causing a miss fire and when more than one miss fire. One cyl isn't gonna cause the engine to stall; it's barely noticeable to most ppl (just as you indicate with your poor mans injector test; you should notice a difference in idle but it won't stall because it's only one cyl)

 

The whole engine is cutting out; it's not like one missfire... Just like you said... if that's the case then it wouldn't run... well it stops running =)

 

It's something more important; like a MAF, cam angle sensor, entire coil pack... something to cause the entire engine to cut out and come back.

[Fairtax4me]

Which of the three wire harness connectors is the one you suspect? Left, right, middle?

[MorganM]

They are almost stacked rather than left to right. It was the lowest one with the most wires. The one above that, in the middle, has a less wires. Then the one above that is just a couple wires.

 

I traced some things to that harnes; cam angle sensor is in that group. Along with both injectors on that side. Not sure what else is in that group... I'd have to trace or get wire colors and refer to a diagram to figure them all out. What a PITA.

[MorganM]

Swapped in a MAF from an Outback EJ25 (either a '97 or 98) that had the same part number as my '97 OBS. Fired it up, let it warm up, drive around the block and no problems. Shut it down for a while, looked over the engine some more, and fired it back up. Drove a couple miles in town (stop lights, parking lots, etc) and she seems fine!

 

I'll consider this problem resolved unless it comes back sometime soon =)

 

I really hate these problems that should throw a code but they don't. Had this happen with injectors, O2 sensors, and now a MAF... at least we have the USMB to help!

[lnelson]

DID replacing the MAF work for you?

 

My car -1996 legacy does the Exact same thing- drives perfectly fine then randomly quits then goes then quits... AT TEMP flashes sometimes when this happens. Nobody seems to be able to diagnose this problem until I read this post!

Please let me know

Thanks

Lloyd

[rallynutdon]

My 96 Impreza was doing this, more so in the cold weather. So when I finally (yes it wasn't the first thing I did, I learned my lesson) opened the hood while the engine was running and waited a minute or two, it was a plug wire, it was jumping the spark from the coil end to ground. Interesting that it caused the whole engine to cut out and never threw a CEL!

[Marco-SUBARU-NZ]

Gidday I have a 1997 Legacy Lancaster Grand Wagon, and have exactly the same problem.

 

I dont even have to drive very far, or sometimes you just start it up in the morning and it cuts out after a few seconds.

 

Had a look at the wiring harness, the sensors, and still no go

Had the complete motor redone 2 months ago, both heads redone, new head gaskets, new gasket set on the entire motor, new water pump, new radiator, spent heaps on the motor, and still have the cutting out issue..

 

I love my suby, all of them, but this one is driving me up the wall

[Nomyar]

Hello everyone, new here and new to Subarus, need some advice. my 97 Legacy outback 187,000m, I think it is the 2.5 Litre. quite running,

 

Changed out the fuel pump now it will start but won't stay running unless I feather the throttle.

 

Had an auto parts store run a scan on it a while back as it was running rough, it would kind of miss on take off from a light and when driving under normal conditions, the auto parts place indicated fuel and air mixture and suggested the first and cheapest part would be the upstream o2 senser, I have purchased the o2 sensor but haven't changed it yet, was thinking about cleaning the MAF sensor first, any suggestions would be greatly appreciated, on a very tight budget as well.

[montana tom]

Cleaning the maf on this problem doesn't seem to help. Change it out with a loaner maf and try running it.

[1 Lucky Texan]

some older soobs have had Crank Pos. Sns be intermittent - usually at temp.

 

knock sensors often crack/go bad on older soobs, no CEL

 

maybe a throttle body cleaning and clean the IACV ?

 

187K - was the timing belt serviced? maybe slipped timing one tooth.

Edited May 1, 2015 by 1 Lucky Texan

[Olnick]

Also consider new plugs and wires.  Use NGK plugs and Subaru OEM or NGK wires.

[Nomyar]

Hello, thank you for the responses, the timing belt was changed out. forgive me for being ignorant what is IACV, will try the things that were suggested and keep you posted.