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Old 11-19-2013, 01:21 AM   #1
TheNewThatGuy
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Default Sever hesitation, engine won't restart, crank position sensor code

So I was driving on a long trip. Out of the blue I get very bad hesitation at all RPMS and at all loads. Like I lost a cylinder or two or jumped timing. I shut of the engine after a few seconds of this symptom, inspect connections, plugs, etc. At this point there was no CEL. I try to restart the engine, and crank position sensor code pops. I check the connection, clear the code, try to restart; no start, code pops. After several desperate, failed attempts at clearing and restarting, I get the car towed back to the house.

Crank sensor tests good at 1900 Ohms (1k-4k range). I check timing, it seems fine. Cam and crank sprocket teeth are all still there, not broken off. I pull heads. No signs of contact with pistons and valves.


I am very confused. If it's electrical, why does the sensor test good and why did it not come on until I tried to restart and not fire? That is classic Subaru "jumped timing" or broke a crank tooth. I am not missing teeth and I made no contact on an interference engine. What the hell is going on? I'm a bit lost at this point.

So now I have new timing belt kit, gaskets obviously.....probably just going to just replace the crank sensor regardless? It was also inspected less than 5k miles before this....installed clean, no buildup. What else should I change or inspect? I like to diagnose what actually went wrong instead of just re-assembling everything regardless.

Any advice?!?!

EJ25 N/A SOHC, for what it's worth.
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Old 11-19-2013, 10:43 AM   #2
TheNewThatGuy
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No one?
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Old 11-19-2013, 12:48 PM   #3
Matt
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Coil pack?

If I remember correctly, the RS has the coil pack on the top on the intake manifold and not individual coil packs on each spark plug.
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Old 11-19-2013, 04:16 PM   #4
TheNewThatGuy
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I put a new coilpack on around 5k ago. I guess I could check it too. Anyone know the resistance of the top of their head??
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Old 11-20-2013, 01:58 PM   #5
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any other ideas?
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Old 11-20-2013, 06:43 PM   #6
yarrgh
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if it's not the sensor, it could be the wiring. what was the actual code?
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Old 11-21-2013, 02:18 PM   #7
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Honestly it was about a year ago, but I think it was P0335. If it was P0336 that would have made me think it was a bad sensor.

Even though the sensor tested good, I'm replacing it anyways....I was gonna check the wiring too, but it seems moot without the engine installed. I also seriously doubt it, because I've seen all the wire bundles and nothing is misrouted, chaffing or cut in any way...

I guess I will put it back together and if it doesn't run, I know it's electrical. Check for spark and go from there... : /
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Old 11-24-2013, 01:22 AM   #8
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Oh, also, something strange I noticed. When I pulled the heads, there were a pile of "flakes" on the "bottom" (side) of all the cylinders. What looks like oil/carbon deposits. I cleaned the pistons only a few thousand miles before pulling the engine, and then it has sat for almost a year.

Also, the remaining coolant has congealed and crystallized. I'd like to clean it all out and hot tank the damn thing, but I am really not willing to break down the short block. I hope/assume when the engine reheats, this stuff will break back down into the coolant? I will probably reflush the oil and coolant after a few hours of use on first restart...
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Old 11-24-2013, 09:42 PM   #9
badharv29
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Ran
in to something similar on a legacy gt i did head gasket replacement on. Turned our broken wire on left bank intake cam sensor. But if I'm not mistaken that car uses same reference signal as the crank sensor
I would check for 5 volt reference on both.
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Old 11-25-2013, 01:19 AM   #10
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I ohmed both sensors, and got nearly identical readings. both almost 2k ohms, which is almost center on the range. I'm going to replace them both anyways. I've seen many people stray away from OEM on these without any reported issues. It's just some wound wire around a magnet. So I'll pick up two for the price of one since they're the same. I will give the connections and harness a good shakedown and test resistance while it's out. that will find any shorts. I suppose I could have tested for spark on start up, but everytime I've seen a Subaru throw a crank sensor code, it doesn't start, so I assumed it wasn't ignition related.

I'm waiting on parts to come in.... When I rebuild it and put it back in I'll let you guys know how it goes, or doesn't. If nothing else for reference.
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Old 01-14-2014, 08:32 AM   #11
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I am having identical issues with my car. I own an impreza gc8 model and I did an engine swap. The engine is a fully rebuilt v7 sti jdm engine and the harness was rewired to be compatible.
The car at times would start and idle very rough and wont rev past 3000 rpm. Did a scan and got code p0335 showing crank sensor. Tried many crank sensors from running cars and same code. Checked for continuity between ecu and sensor and it was good. Sensors were tested and appears to be good. Im waiting on 2 new sensors cam and crank sensors. Im thinking of getting a new crank sprocket. What else can I do or check? I checked my coil packs and there was spark. What next?
Was your issue ever resolved? If yes tell me what you did.
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Old 01-14-2014, 09:55 AM   #12
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You might want to check your wiring. And also there are different tooth patterns on the cam/crank sprockets between years.

I rebuilt the engine. I found nothing wrong, but I haven't put it back in yet. I swapped the sensors with new ones anyways.
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Old 01-14-2014, 12:43 PM   #13
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I will do that. It is puzzling. It was a direct swap from a running v7 sti jdm spec. All we did was change seals and bearing and rings and rebuild fresh. What was done was the harness was modified to be compatible with the gc8 dash but the part leading to the engine remain untouch. I plan on changing both cam and crank sensors to new ones and as you suggested recheck all the wires leading to the ecu
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Old 01-15-2014, 08:35 AM   #14
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I am puzzled. Its a direct swap from a running car that crashed. All what was done is rebuilding changings seals and bearings and got the harness rewired so my dash could be plugged up using the v7 harness. Im about to change both cam and crank sensors and recheck all those wires to the ecu. any suggestions from anyone???
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Old 01-22-2014, 09:58 PM   #15
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Just an update on our findings.

All this time the culprit with my crank sensor code was because of the Air Flow Sensor.

I purchased a generic brand thinking the part numbers match and it will work. to my surprise we decided to get an oem air flow sensor from a friend's STI and the car idle perfect without any codes or issues.
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Old 03-01-2014, 08:30 AM   #16
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Still haven't run mine since the tear down. I'm taking the time to put my front LSD in and popped in a 20kgf center diff. The trans is back together, I just have to lash the front diff and pop the engine and trans in now. Maybe next weekend when I have time.
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Old 03-18-2014, 01:13 PM   #17
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Well, finally finished putting the car back together today. First try fired right up, so I have no idea what the issue actually was. But from the tear down everything looked good, so perhaps it really was a sensor, even though they ohmed good, I replaced the cam and crank sensor anyways.
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Old 03-19-2014, 02:32 AM   #18
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It sounds like you finally did the first thing you should have tried. It doesn't matter how it reads, try anyways. Buying and testing a new sensor is far, far easier than all the work you made for yourself. Plus if there was no change, you could have simply returned the new sensor for a refund, no money lost. At least you got to do some other work on your car while you were taking everything apart.
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Old 03-19-2014, 03:03 AM   #19
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Meh, I was taking it out anyways to go back to my h6.
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Old 03-22-2014, 09:23 AM   #20
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I know this is fixed... but for future reference.

I had these symptoms, along with the "At Oil Temp" light. After ALOT of trial and error, it turned out that the Crankshaft Position Sensor had debris stuck to the end of the sensor (it's a magnet, and attracts metal shavings, metallic dust from the road). Pulled the sensor out, cleaned it off, reset ECU by pulling battery terminals and touching together. Started perfect.

And I wasn't getting a crankshaft sensor code...
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Old 04-03-2014, 01:46 AM   #21
TheNewThatGuy
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That's really common to get a weak signal from metallic shavings. But I had a code for it, and my engine wouldn't crank, so it's not really the same problem.
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Old 04-30-2014, 02:02 AM   #22
TheNewThatGuy
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So, out of no where, my engine won't start now. It cranks, but won't start. I got to the track yesterday and had to push start the car the rest of the day. The engine runs fine, there's just something not letting the engine start. I did get crank position twice from about 20 or so failed starter cranks. Since I just did timing and checked everything, and replaced the sensor, I'm gonna shoot wires and shake the harness. Anything else stupid sensor related that can cause is needed to start but not run? Like the neutral switch or something? 2.5 manual.
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Old 05-11-2014, 03:26 PM   #23
TheNewThatGuy
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Well, car has been running fine for days now after it sat for awhile and dried out. Now that it rained again, I started in my garage fine, drive to work in the rain, parked, shut it off and immediately tried to restart. Same issue. It won't start when wet. So that narrows it down a bit and I'm really thinking it's harness related. Still no codes. Getting irratated, any ideas?
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Old 05-13-2014, 02:26 PM   #24
TheNewThatGuy
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Doing it all the time now. Dry or wet. I replaced spark plugs, I have fuel and spark on crank...I hooked up a running car just to eliminate low volts. It still runs fine after a push start. The starter sounds great even. On occasion there's a very big backfire while cranking. Still no codes at all and yes timing is still good. What the hell is going on?
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Old 05-18-2014, 09:26 PM   #25
TheNewThatGuy
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I slaved in a spare ignition cylinder just to rule that out, also. No change.

I pulled the entire engine harness and shot every pin to check for resistance. shook the harness while doing so but still had less than half a ohm resistance on every wire. Found a couple cracks in insulation, heatshrinked them and reinstalled the harness.

I pulled the new crank position sensor and it ohmed at 1,950 ohms.

Tomorrow I'll read the cam sensor, even though both cam and crank are new, then try to restart it. I'm really running out of ideas. I know the harness is good now. I know the car turns over, gets fuel and spark, mechanically it's good, electrically (volts and grounds) it's good, so I guess I swap sensors one at a time until it starts...

Anyone know the bare minimum sensors/solinoids required to start the N/A engines?
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