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Was swapping identical parts between '07 and '08 Outbacks and have a no start condition where the car I borrowed parts from was running fine prior. 

Car is 2008 Outback wagon auto trans, 175 k miles, previously running fine until today. Recent purchase about 6 months ago with broken timing belt. Got car working several months ago and has been running great. Am having issues with my '07 so I was using the '08 to borrow parts. I swapped a known good MAP and coil pack over from the '08 to the '07. I also actually ran the '08 with the '07's suspect coil pack and got cylinder 1-4 misfires immediately on test drive, confirming the issue with the '07 which is also having misfires. Also get a strange EGR code, P1492 in the '08.

So bottom line is now after putting the '08 into its original state with its original known good MAP and coil, and resetting all the codes, I try to start it and it won't fire. Just cranks. Sounds fine otherwise, like battery is strong (2019 battery). Doesn't make any noises like compression or timing is off. I get a P0335 code immediately, even before cranking the CEL was flashing, which is new, which is a crankshaft position sensor code. I didn't touch any part of the harness near the crank position sensor, didn't mess with the timing cover, just removed the snorkel so I could get to the coil pack. All vacuum lines are reconnected as far as I can tell.

So a previously running car now won't fire, probably because the ECU doesn't know where the crank is. The freeze frame on my code reader says the control voltage is 10 volts, during cranking, which may be low? Could also be total randomness in that I have a bad crank position sensor all of a sudden. Or could I have created a situation from the misfires, with the EGR and CPS code showing up all of a sudden? The engine seemed to stumble a bit on the test drive, once around the neighborhood at low speeds. I replaced both ground straps (were rotten) when I did the heads several months back. 

Battery voltage at no load is 12.4V, probably not the issue but I'm charging the battery anyway and have also pulled the negative battery cable to reset the ECU. I can swap the crank position sensor from the '07 if I need to. 

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So charged the battery for a few hours with the battery disconnected, and it started right up with a normal fast idle. When I put it in reverse (an auto) it started idling slow, searching, near stalling. Put it in park, and it stalled, making an odd sound, some kind of mechanical clunk. Getting weirder. No codes or dash lights. Battery is 12.6 with car off. Maybe I need to perform the idle relearn procedure. Maybe the crank sensor is intermittently failing.

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13 hours ago, 89Ru said:

...and it stalled, making an odd sound, some kind of mechanical clunk...

Could be the crank-pulley being loose or coming apart, or the timing-belt tensioner being loose?

Worth checking these out, if you haven't already.

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9 hours ago, forester2002s said:

Could be the crank-pulley being loose or coming apart, or the timing-belt tensioner being loose?

Worth checking these out, if you haven't already.

If the crank pulley was wonky that could make a clunk, but the crank sensor is timed off the crank sprocket and I can't figure on that backing off the snout. Still worth a look, will pull off the timing cover and check it out. 

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I read once, only once, of misfires apparently caused by debris on a crank sensor - so, I guess wipe it clean while you're in there? They seem to be built with a magnet inside and maybe ferric dust collects on them???

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once it starts youll need to drive it.. THis year subaru needs to "learn" how to properly run the engine after the battery has been disconnected.. same thing happens after you clear the check engine lights. They will run like crap for a short while then usually run fine after.  

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Finally got down there. Nothing appears obviously wrong after pulling off the belt covers. Crank pully no wobble, crank sprocket is ok, woodruff key on snout is ok. Removed all the timing belt pulleys, all ok. All timing components were new OEM at last replacement 6 months ago, including the tensioner. The tensioner bracket is good, threads aren't stripped. All bolts were tight. Gonna take me a while to get it back together, work is so backed up. Probably going to seafoam the intake for good measure after it starts running semi normal, and do the idle relearn procedure and hopefully it "learns" how to run again lol. I'll check for magnetic bits on the crank sensor, thanks Texan. 

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Back together after finding nothing wrong behind the timing cover. Attempt to start, sounded ok, just cranking without firing, then after a few cycles the engine sounds changed, like the wheezing sound it gets when you pull the plug wires like doing a compression test. Checked the ECU and it had a P0335 code, which is crank sensor, which I saw before. 

So I swapped the crank sensor from a running 2007 outback wagon manual. No change. Still cranks without firing. Moving the 2008 crank sensor to the 2007 doesn't break the '07, it runs fine. So the sensor appears ok.  During cranking the OBD reader momentarily reads 8.5V, then stabilizes at 10. Reset codes and repeat, get a new P0335 code again with flashing CEL while cranking. Recall I got the P0335 code before diving into the tbelt cover.

So a previously running car now won't start after running with a known bad coil.

Some possibilities.

1. The bad coil did some damage...to what. Wires/plugs/ECU/crank sensor circuit. 

2. Belt slipped a tooth on startup...can check with compression test.  

3. Battery is failing?  On the charger again.

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Suspecting a grounding problem due to large voltage swings seen by the OBD reader while cranking. Cleaned up the engine compartment frame rail grounds which really weren't too bad since I had just replaced two that were rotted. Attached some heavy jumper cables from the body to the intake. Reset codes. Tried to start, just cranking. Got the same P0335 code again. On the 2nd attempt it STARTED right away and sounded normal. Cut out after about a minute. Further attempts to start, nothing, but it sounds back to normal like the spark is firing during cranking which is a change. Took the jumpers off wondering if the giant ground loops were picking up interference, no change.

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brief search shows that code can be caused by spending too long between ON and START ?

 

seems weird, but maybe something related to ECU 'sensitivity'/race conditions. could explain why a poor ground or harness connection somewhere might cause it?

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1 hour ago, 1 Lucky Texan said:

brief search shows that code can be caused by spending too long between ON and START ?

seems weird, but maybe something related to ECU 'sensitivity'/race conditions. could explain why a poor ground or harness connection somewhere might cause it?

That's interesting. I am spending a fair amount of wait time between ON and START, mostly to set up the OBD reader communications and also since 20 seconds is the wait time for the Idle Relearn procedure. This is my 16 year old daughter's car, that I broke borrowing parts to fix my car.  I'm gonna have some splaining to do if I can't fix these unstable moods. She thinks my car's bad juju infected hers.

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Well I tried various combinations of the ignition key's ON-START time such as instant on (no wait, just turn key and fire in the hole), to several seconds wait, its still groundhog day. It did sputter one time but no start. With the ignition key in the ON position, I can hear engine compartment relay click and under passenger dash relay click, and also hearing the fuel pump whirr up for a second or so. Tried putting the jumper cable ground in different spots from body to intake without a huge loop without any difference. Still getting P0335 right away after clearing codes. So looking like I need to dive into the harness. Funny how I'm just now remembering that I had this same problem on a 98 OBW where the harness pigtail connector that mates to the crank sensor had a broken wire, with the exact symptoms, left me stranded that time, crank no fire, same P0335 code too. 

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