Warm engine starting problems:
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This is a discussion on Warm engine starting problems: within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; Hello Subaru rocket scientist. Here is one for you all: I bought a 2006 subaru WRX brand new with 20 ...

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    Registered User VooDoo_Rex's Avatar
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    Warm engine starting problems:

    Hello Subaru rocket scientist.

    Here is one for you all:

    I bought a 2006 subaru WRX brand new with 20 miles on 3 years ago.

    ZERO mods, all stock, nothing changed at all.

    Problem since day 1 and the dealer ship cannot reproduce>>>>> of course:

    LONG DELAYED STARTING TIMES. 5-7 SECONDS AFTER ENGINE HAS RUN FOR A WHILE AND HAS COOLED OFF SOME BUT NOT COMPLETELY. CRANKS OVER QUICKLY BUT SLOWLY RUMBLES BACK TO LIFE WHEN STARTING BACK UP.


    First start of the day is perfect. If I drive to full engine warm up and then shut the car off, then come back in a hour the car will start hard and slow. It will kind of sputter when starting back up and actully not run very smooth at idle. Again this is with a slightly cooled off engine. Does not do it every time but nearly 75% of the time.

    Water in the fuel line? Nope, I tried using "stabil" fuel treatment in several tanks of fuel with no effect.

    Octane problems? I use Sunoco 93 octane always and have even tried octane booster a couple of times and again no effect on long starting problem.

    My guesses: Bad fuel pump, air leak when engine is warm, lean fuel mixture at low RPM when warm, tumble valve generator sensor problem, grounding problem?

    Lastly, if I anticipate a long start up before I turn the key and push down on the gas pedal slightly like they use to do in the 60's it will start up much quicker but still not as quick as a cold engine start. This is why i suspect a lean fuel mixture or air leak.

    HELP ME PLEASE, THIS IS DRIVING ME CRAZY ON A NEW UNMODED CAR.


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    Moderator Donkey's Avatar
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    I have heard of this happening to some.I think the evap purge valve at the manifold or the tank purge valve is the culprit.I would search NASIOC (service/maintenance or 2.0L sections) for more info.
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    Sammich Makin' Pwincess wrxtreme06's Avatar
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    Quote Originally Posted by Donkey View Post
    I would search NASIOC (service/maintenance or 2.0L sections) for more info.
    he has a 2.5L

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    Hi guys, i have a 2002 STI, 2 litre engine and my car does the exact same thing as this, please help me

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    Registered User Murt's Avatar
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    Engine temp sensor maybe at fault.

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    Quote Originally Posted by Murt View Post
    Engine temp sensor maybe at fault.
    i seen something said about this somewhere, something about the car not reading the temp properly via the sensor and getting the mixtures wrong.... wouldnt this sensor throw a CEL if it was playing up?

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    Registered User buggedout03's Avatar
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    I've had this problem a few times on my 03 but the dealer couldn't figure it out cause it wouldn't happen for them. Usually in the mornings it starts up right as the key goes all the way but later in the day it is delayed to a few seconds. It only sputtered and had a hard time with it a few times though.

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    Quote Originally Posted by buggedout03 View Post
    I've had this problem a few times on my 03 but the dealer couldn't figure it out cause it wouldn't happen for them. Usually in the mornings it starts up right as the key goes all the way but later in the day it is delayed to a few seconds. It only sputtered and had a hard time with it a few times though.

    yeah my car starts perfectly when cold, but warm starts it carries on like a carby car and takes 3 secs odd to fire up and then it idle's perfectly..... its really annoying

  10. #9
    Registered User Murt's Avatar
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    I'd guess Engine Temp sensor because my wagon started fine

    from cold, if i parked up and the engine was any way warm if

    i'd try to restart it'd be a real hard to get going. If you could

    also attach an extra earth/negative lead to the battery and

    body of the car, that'd also help with quicker starting.

    Keep us posted how you get on.

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    Quote Originally Posted by Murt View Post
    I'd guess Engine Temp sensor because my wagon started fine

    from cold, if i parked up and the engine was any way warm if

    i'd try to restart it'd be a real hard to get going. If you could

    also attach an extra earth/negative lead to the battery and

    body of the car, that'd also help with quicker starting.

    Keep us posted how you get on.


    yeah im pretty certain its the coolant temp sensor as there are many threads on the net abouot all different cars with the same symtoms as what mine and others are doing and all there threads also point to the coolant temp sensor....

    got 1 on order from subaru and il swap it out over the weekend and let you guys know the results, thanks

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    okay yesterday i changed the coolant temp sensor, also cleaned the oil pressure switch spade fitting ( was right there so i thought id do it ) then i cleaned the crank sensor aswell....


    BUT no good, still a ***** to start warm.....

    now im out of idea's.... a mate said a leaky injector but that
    would surely affect cold starts.... it plays up maybe 1 out of 10 on a morning start..... but 100% on a warm start ie: car left for over 3 hours or more, or every afternoon when i leave for work which is a 8 hour time gap from morning start up it plays up all the time....

  13. #12
    Registered User Murt's Avatar
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    After all that no joy, sorry to hear theres its not fixed.

    Hopefully some else on here can help.

  14. #13
    Admiral Ackbar the 1st mycologist's Avatar
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    What happens if you turn the key to on first and let the fuel pump prime for a few seconds before you turn it to start?
    "From a little spark may burst a mighty flame." - Dante
    "The stitch is lost unless the thread is knotted." - Italian proverb

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    Registered User 2:43AM's Avatar
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    I don't know why a coolant sensor would be to blame for a sputtery start.

    Sounds to me like a fuel pressure problem, so let's do some experimenting...

    On a cold start, turn key to ON, but do not crank. Listen for the fuel pump and try to time how long it's on before it shuts off, meaning the fuel system is pumped up to pressure.

    Next, on a warm start, do the same. Does it take longer?

    If so, then either clogged fuel filter, line or bad fuel pump or low voltage to the fuel pump.

    EDIT: Mycologist beat me to it! But yes, I'm in agreement with him since he answered first!

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    thanks for the input guys, well the pump prime's for around
    3 secs, this has never changed as its a walbro so you can hear quite easy, i also let it prime before i crank the car everytime....

    now i did this as a experiment and it worked, will do it everytime and try to find the prob this way....

    got in the car and didnt put my code in ( brant keypad alarm )
    and cranked it 4-5 times ( no pincode means it wont fire up )

    then i put my code in and started and it fired up perfectly.

    now im thinking what could the prob be now, almost as if the cranking cleared fuel from the cylinders and then allowed it to fire without a prob.....

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