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subaru impreza turns over but doesn't start (intermittently)


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mussen
Novice

Mar 13, 2015, 4:55 PM

Post #1 of 17 (1313 views)
  post locked   subaru impreza turns over but doesn't start (intermittently)  

Subaru Impreza 2004 2.5 TS

For a couple of months now and every few days, my car won't start. Everything sounds normal on start up but the engine won't fire, unless I give it gas. I can keep the engine on with the gas pedal but as soon as I release it the engine chokes. When it's running it runs like a dream....no knocking or shuddering or poor idling at lights.

I've had it at the dealership at various times and they've checked everything and found nothing wrong with any sensors, air filters, fuel pump, no error codes or check engine light etc. The spark plugs were changed a year or 2 ago, the fuel filter was changed recently and there are no leaks or pressure problems registering. When I went to pick it up today and while I was talking to the mechanic, it finally didn't start. He hooked it up and found a CAM sensor error, however he had just unplugged it while the car was running, so maybe it came from that. He is going to check the sensor and the wiring on Monday but then he thought it was the gas pump since I could keep the engine going with the pedal (therefore not the CAM sensor?). I just don't see why the fuel pump would only fail occasionally at startup and never when driving (?)

Does anyone have any thoughts on this matter? The last time it failed it wouldn't start for almost 2 hours so I called a tow truck thinking it had finally died, but as soon as it rolled off the truck at the dealership it started right up. (Of course).

Thanks for any ideas anyone might have.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Mar 13, 2015, 5:13 PM

Post #2 of 17 (1304 views)
  post locked   Re: subaru impreza turns over but doesn't start (intermittently)  

? You aren't giving it gas by holding "gas" pedal just requesting another RPM speed - the car decides how much fuel to deliver.


Intermittent stuff like this can be a royal PITA as you well know. Seems nothing checked is down while checking and nothing in memory so will have to catch this exactly while it's happening and see what's dropping out.


With nothing showing I venture the guess that if you can rig this to watch fuel pressure while it's not starting you'll find it far enough below spec to be the problem. Seems you've had some time with it not starting so a good time right then to prime it in throttle body would do as a test and if it fired up for a few seconds (don't touch the gas pedal) you at least would know it's a fuel delivery problem not caught by a code yet or in person by anyone,


T



mussen
Novice

Mar 13, 2015, 8:25 PM

Post #3 of 17 (1284 views)
  post locked   Re: subaru impreza turns over but doesn't start (intermittently)  

Thanks for that info...that really helps me wrap my head around this. And I'll try your recommendation and update when this issue is solved.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Mar 14, 2015, 4:47 AM

Post #4 of 17 (1276 views)
  post locked   Re: subaru impreza turns over but doesn't start (intermittently)  

Things like this playing hide and seek stink no matter what it is automotive or other thing. For a car you want to narrow it down at least to what it lacks to start so you can concentrate on just that.


The real hassle is it may have to involve YOU or pay a tech to take the car and use it till it happens ready with test equipment.


I guessed (best I can do if a dealer has had it a few times and found nothing) it's a fuel issue. That would be anything from the damn gas tank is really empty (have had those road calls) and gauge fooled owner that it wasn't!


Plenty of techs and DIYers would begin a parts tossing game in hopes to hit on the problem but with this like any like it if you do many things all at once you never know which was the problem - frustrating even when fixed - what was it?


That and if new stuff is in fact defective or wrong in some way it super complicates it. If you paid a tech some rate to spend hours till it happened (could take that) it could get wildly expensive all something you work out with who is willing and able to do what fast while this happens.


Do check that any theft control items are NOT causing this and know how any of them work either a factory or aftermarket (more troubles with those) what it is supposed to disable IF IT WAS WORKING PROPERLY so easier to rule those type things out or in if the case may be.


See if you can find or think of any common denominators for when this has happened. Like - only first cold starts for day and never subsequent starts, only when cold, warm, wet, dry, on a slope/hill or something. These issues stink,


T



mussen
Novice

Mar 14, 2015, 11:10 AM

Post #5 of 17 (1267 views)
  post locked   Re: subaru impreza turns over but doesn't start (intermittently)  

I can't see any good indicators: not terrain, temperature, it'll happen first thing in the morning or after 5 stops on an errand day. The only constant is that it's a start issue and not a driving issue (yet anyway). I know a failing fuel pump can cause these types of start issues but I would have thought I would notice something while driving. Anyway, the dealership has been good about not charging until they find a diagnosis. A mechanic even drove it home one night (and agreed it runs really well). At least now that he's seen it fail he might not lose interest. He did seem to get it to start easily by lightly holding the gas pedal instead of pumping it or not touching the gas at all, which is all I've ever tried (not so as to flood it). Maybe that might indicate something.

Thanks again for your input!


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Mar 14, 2015, 11:55 AM

Post #6 of 17 (1263 views)
  post locked   Re: subaru impreza turns over but doesn't start (intermittently)  


Quote
For a couple of months now and every few days, my car won't start. Everything sounds normal on start up but the engine won't fire, unless I give it gas. I can keep the engine on with the gas pedal but as soon as I release it the engine chokes.


That sounds like the symptoms of a problem in the idle air control system. Make sure your battery tests good and the connections are clean and tight. Its important because a weak battery or poor connections can actually cause the engine controller's memory to reset during cranking. If learned idle motor data is lost, it might cause idle issues till it is relearned.

If that is all good, I'd remove the idle air control motor. Then clean the pintle, bore, and throttle bore with carb cleaner. An old tooth brush and rifle bore brush works pretty good for cleaning the pintle bore and throttle bore. Point the idle air valve down when you clean it, so the solvent doesn't get into the electrical portion of the valve. See how that does.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Mar 14, 2015, 11:58 AM)


Tom Greenleaf
Ultimate Carjunky / Moderator
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Mar 14, 2015, 12:00 PM

Post #7 of 17 (1261 views)
  post locked   Re: subaru impreza turns over but doesn't start (intermittently)  

I feel for you with probs like this. So far so good with a tech who drove it and it happened. Holding throttle IMO is allowing more air for RPM which may cover too much or too little fuel delivered for just that time - not a fix but worth noting.


So, I think you are on you way to finding it. Just FYI when (now ages ago) either local shops or people with these would crater to giving up a vehicle taking wild amounts of time to catch and I would volunteer to drive them (assorted issues) for my own errands and use with agreement from all and watch all vital signs waiting for it to happen. Seems like and is a bit masochistic work but I get a car to use (local please even I don't want to get stuck out there) and put up with devices and gauges up to under windshield wipers or what I could catch with what.


So far I'm just trying to find a common denominator. Could even be low voltage (happens when cranking as that's the largest load on battery) which throws off the power available to fuel pump AND other controls for a clean fast start. See, once running you have alternator voltage not lower cold battery while cranking so things stay in spec and battery stays strong long enough with a then easier to crank warmer engine and wouldn't show up so easily all over a low power available as just an example of how some of these nasties could happen. Clue hidden in this is that it seems to start right up or did once after a couple hours, not stone cold but time for a flooded engine from trying to dry out and if battery not drained actually might have more power later if not overworked when failed. Just an example.


I have just one left but a fast voltmeter you put in a power port or cig lighter for instant situation for volts available that has helped me with some that behaved almost all the time.


Another was really watch fuel pressure rigged up to see it thru windshield!


Another again all random but died out without anything in common rigged (made for this) a trigger wire to starter such that with key in "run" position (and in park, parking brake on known working well) crank and look then and quick be able to prime with fuel(starting fluid my choice) if fuel was lower or dropped out see if I could get it to react and rule things out or perhaps got that one going and off to really hone in on why it was off and nicer to know you really found something for a cause.


That may be the way to target it with willing people or YOU if you can rig it up.


Another is to have a strong jumper box also at the ready such that you are sure it get proper power and volts with two working and if that instantly snapped it to working then off to find out if battery is the issue or connections or just old enough it could be intermittent - just had one on my own new, one month lost spec before even starting up which it did and got a new one so this wouldn't leave me stranded! MY OWN!


I'm trying for you as to what could be done to find this if you have this type help and or your own stuff available to do that. This would NOT be cool for many people to set out say with a car full of other people, children taking them to assorted schools, daycare or something at all IMO.


Worst thing is when nothing fails and have to give up and say you didn't find anything in the world wrong but you already had some of that with people who didn't probably have enough time yet.


Keep at it,


T



mussen
Novice

Mar 14, 2015, 1:51 PM

Post #8 of 17 (1256 views)
  post locked   Re: subaru impreza turns over but doesn't start (intermittently)  

This sounds like a very likely problem. My battery tested fine but it's at its average life expectancy anyway. I said this once but it was dismissed as a possible problem because of how it tested. Thanks so much (and I'll work my way through Tom's suggestions if that doesn't worl). If I don't check in again, that was the (embarrassingly simple) solution!


Tom Greenleaf
Ultimate Carjunky / Moderator
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Mar 14, 2015, 4:32 PM

Post #9 of 17 (1251 views)
  post locked   Re: subaru impreza turns over but doesn't start (intermittently)  

Back for a bit - sorry can't be at this constantly.


Two things ring true with cars - any. Only thing that touches the road are the tires and only power supply is from battery that is kept at charge by an alternator such that if voltage wasn't right or amps (power/force of the connections or 'amps' able to get to an item) so if either is off the items (motors want proper power as does about everything) they might still work but not in spec and one spec off is like a Domino effect - other controls get incorrect but credible bad info on what should be doing what, when and where. Do you kinda follow me on that?


The thought is if power while cranking is low (in this case while starter motor is sucking up most of the available power) so is the fuel pump getting less actual power or less than it takes to spray fuel at proper amounts but still works some just wrong and either too much or too little at start really might not fire at all yet still wet/flood spark plugs which could explain why waiting seems to matter as they dried out for the try later? All guessing but an area to know is correct and is on the suspect list for this elusive flipping problem.


Real example of my own and observed like I'm telling you: I plow snow, live in New England (12-14 feet in just Jan-Feb this year you may have seen on the news. Plow is HD as can be had for a 3/4 ton HD truck and plow power to move it up, left or right (plow weighs over 800 lbs (more than the engine by lot) and run by a electric motor about twice or more the power of any starter motor. So, if engine is running both battery and alternator are powering it. At idle it strains them both and as mentioned I watch voltage drop off while lifting the plow while running at idle drops from ~13.8V to below 10V instantly! If at a raised idle will hold higher voltage and plow is faster - ----- just an example as your fuel pump is an electric motor too just smaller.


So, I have for reasons needed to lift the plow but not start the truck. No help from alternator just plain battery and it's noticeably slower so much the interior light dim.


That's why I'm thinking of this "intermittent" crap could just be a split second or two of low voltage + power for the fuel to be delivered properly and not start but later all testing proves fine.


You don't need to blame a battery yet just test what is happening where and when and with high hopes catch it and be much more certain you've nailed down the cause - hope it will misbehave and you catch it. That's the PITA with any intermittent bull,


T



mussen
Novice

Mar 15, 2015, 4:42 PM

Post #10 of 17 (1236 views)
  post locked   Re: subaru impreza turns over but doesn't start (intermittently)  

Soooo I got a new battery and it hasn't fixed the problem. It happened on the second time I started the car after installing it. But i did manage to get it going right away by pressing the gas pedal as lightly as I could without stalling it and after about 15 seconds it stayed on by itself, just like the mechanic did. I'll get him to eyeball the fuel pump and check the wires, although a loose connection is probably not remedied by just giving it enough time idling to catch. I still don't understand why a fuel pump would fail on start up only. The starter taking away too much voltage makes sense but surely a new battery puts that theory to rest....

I'm sure one day this will be solved.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Mar 15, 2015, 11:27 PM

Post #11 of 17 (1229 views)
  post locked   Re: subaru impreza turns over but doesn't start (intermittently)  

OK - mostly rules that out but still need to watch what is the voltage when it happens new battery or not. Some are NG new but with same problem is mostly ruled out IMO. Personally I have no issues with replacing batteries with some age on them as almost all the dependability drops off after a few years yet some do well over 7 or more? Go figure?


Now I suggest a high end code reading. Even without a warning light for a MIL (malfunction indicator light) some can be pending and if this stalls it must know what circuit it's in but not enough to light a warning yet. If when you have codes checked don't let the person/tech clear it as that info can only help.


Have to give you credit for your persistence so far. Most techs or owners would give up and trade out for another vehicle when it just plays games too long,


T



mussen
Novice

Mar 16, 2015, 9:17 AM

Post #12 of 17 (1215 views)
  post locked   Re: subaru impreza turns over but doesn't start (intermittently)  

I suppose it's safe to assume there's a gas delivery problem at startup. If I rule out the pump I'm left with relays and wires.

Now thinking about wiring, a few years ago I noticed I could no longer leave my highbeams on. I could hold the lever and make them stay on, but pushing the lever into the on position no longer works. Also, recently and only once, on a -26 C day, the air compressor was dead when I started the car. After stopping and starting for a half an hour I noticed thankfully that it had come back on. Does this sound like it could be connected?

Anyway, I'll get the relay changed and perhaps just wait until it properly fails to further problem solve it if that doesn't fix it.


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Mar 16, 2015, 9:35 AM

Post #13 of 17 (1209 views)
  post locked   Re: subaru impreza turns over but doesn't start (intermittently)  

Instead of playing swaptronics and spinning the guess-o-wheel, why don't you test to verify your assumption. If you think you have a fuel delivery issue, connect a fuel pressure gauge up and see what the pressure is when the engine doesn't want to start.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Mar 16, 2015, 9:58 AM

Post #14 of 17 (1205 views)
  post locked   Re: subaru impreza turns over but doesn't start (intermittently)  

Pump is NOT ruled out! Fuel delivery could be confirmed by spraying starting fluid into throttle body when it absolutely will not start but cranks it would/should at least react or run for a couple seconds - proof that fuel isn't correct. By insisting on calling it delivery that's to include ANY REASON it's not delivery any, too little, too much - anything.


Battery could be fine and connections may b weak! You would need to catch each spot and watch for voltage drop while something happens. In that now you said other items are involved I would check out or toss the first things from battery beginning with u-clamps, wire to next item and on. Both fuses and relays ABSOLUTELY CAN LOOK OR TEST OK AND PULL CRAP ON YOU. Relays are about of them points inside that make contact that could be better or worse at assorted times. Just a connector in a harness - anything.


Relay: Had more than one go low or bad and one took me months to catch with the intermittent crap. That was power locks in that case they always locked but not always fully opened which in that case required more power then locking. If that car was running the voltage was higher and they worked and kept working for a good while if shut off. Battery was old enough and usable for other things so tossed it and they worked for a whole month then back to intermittent. Finally just tossed the relay as it was one very hard to get to and was there for something else and sucker worked right forever more!


That's the long version of things on the list that could and would test fine when working to mess you up dammit.


OK - you mentioned high beams no longer work AFTER an attitude. Know that low voltage at the spot of connection would get hot and either go lousy or might get better and also could just quit even though contacts touch. All will be temp sensitive to some extent.


So now with the headlights the connection is probably ruined if can't be filed clean and the "flash" for high beams is a different connection so consistent to me with poor power delivery for these items.


You have you clues better now than at first so testing along the way now should even show partial issues even when it's working but enough for no problems.


Most have noticed that a starter motor will just flutter is power is too low usually just a low battery. That's on purpose as if it delivered steady low power the starter would overheat because it wouldn't turn and harm or ruin it. Same with other things that don't have that for protection - all starter motors I know of do.


I know it's a tad confusing but think this issue has now been hiding for a while and just hasn't fully finished messing things up!


I'm pretty sure now this could be found but the damage of something like the fuel pump might still be there. Lots of work to blame it for sure as harmed by this and a lot of money and effort to just toss and be wrong.


It might save you a ton of more headaches to find a real good "auto electric" tech with a outline of what has been a sequence of events leading up to where it is now and nail the sucker down once and for all!


T



mussen
Novice

Mar 16, 2015, 10:14 AM

Post #15 of 17 (1202 views)
  post locked   Re: subaru impreza turns over but doesn't start (intermittently)  

: ) I'll update if I get any answers!


mussen
Novice

Jul 13, 2015, 2:45 PM

Post #16 of 17 (1076 views)
  post locked   Re: subaru impreza turns over but doesn't start (intermittently)  

I just wanted to update this old post with the solution I found. Certainly cleaning a few sensors as suggested helped but what nipped the problem in the bud was running a fuel system cleaner through the gas tank and switching to premium gas. I haven't had a problem in 2 months : ) If only I had tried the simplest solution in the beginning....I should have done that anyway given the age of the car.

Thanks for everyone's input!


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Jul 13, 2015, 4:17 PM

Post #17 of 17 (1074 views)
  post locked   Re: subaru impreza turns over but doesn't start (intermittently)  

That is interesting. Thanks for following up on this. Even the simpliest of things can cause headaches. Angelic

Thread closed as solved. Can be reopened upon request by the OP.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.






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