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Hi guys, just after some opinions before I spend out on new parts.
The last week or so I've been having issues with my impreza when driving, it seems completely random too, I can be driving along and the rev counter drops to zero and the engine dies, sometimes it will pick back up, sometimes it just rolls to a stop and I have to turn the ignition off and on again to re start. It seems to be slowly getting worse and last time out it died on me twice in the space of a mile.
Being a mechanic I'm thinking it's probably a crank sensor fault due to the fact the rev counter drops to zero, but I'd like some feedback and any other possible ideas.
I had the same problem - turned out to be the immobiliser........................
(rev counter drops to zero, engine dies. leave it sitting for 30 secs, turn on iginition and engine would start. Once, on motorway doing 60, engine died, I just turned ignition on/off and car picked up!!)
Quick update, after checking the car over yesterday I found a broken vacuum hose that goes to the fuel pressure regulator. I replaced this, I also removed and cleaned the crank sensor. Last night I drove it nearly 40 miles to test it and it didn't miss a beat.
Not sure if I have fixed the fault yet but before yesterday the fault would occur within a mile of home. Fingers crossed.
Nice timing, I just experienced similar issues today when having a roadtrip.
Started with engine cutting out upon larger vibrations (running over groves in pavement.) but then picking up an working as perfect as usual.
After a while it started to cut randomly, under load without load, just idling.
First assumed it was the knocksensor picking up on knock when running over bumps due to running very stiff shocks, and having the sensor changed recently. So tried disconnecting it completely and resetting ECU.
No solution there so I guess this rules out the knocksensor raising havoc.
I am not getting any faultcode as it seems ECU looses power as well when this is happens. I assume this due to the fact that the engine CEL is lit but then goes out when revs drop? Which makes troubleshooting a PITA...
(I ofcourse get the Knocksensor code when having it disconnected.)
So I am guessing this is some sort of electrical issue.
I made a short vid where you can see what happens, you can also see the CEL being lit and then turning off when revs hit 0.
Been playing with the car today, thought I had fixed the problem after the last post, until this morning when it happened again 100 yards from my house!
After playing with it for a few hours today I have found the deffinate solution, my fault is the square brown relay up under the dash which I believe is the fuel pump relay and it must supply something else too.
I noticed that when my fault occurs the CEL light will stay out and it won't restart untill the relay clicks back on and the CEL light re appears on the dash(sometimes after a few seconds, sometimes instant, sometimes after a couple of mins!). So I just started unplugging things until I could reproduce the fault. I have replaced the relay now out of my spares collection and will be testing over the next few days.
Last edited by redscoobymann; 12 August 2012 at 20:39.
Edit: Found the source of the problem, it was the ScoobyECU that wasnt properly fastned in its socket.
Not really sure if the short circuit was caused by vibrations or by increased voltage at certain revs, or both..
Either way, all is fine after setting it properly in its socket.
Don't know if this will help anyone else, was easy enough to locate by poking the ECU with the engine running..
Last edited by deleterious; 19 August 2012 at 17:09.