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Old 11-28-2008, 09:34 PM   #1
jt0thevizzle
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Default Car wont start after resetting ECU

Is that normal? My car didn't start the first time after I reseted my ECU. It seem as though it was going to turn on but never did. It took the 2nd try for it to turn on. I reseted my ECU twice, and both times that happened.

Btw both time I waited like a 2-4 min after hooking back up the negative terminal too.

I just want to know if that was normal.
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Old 11-28-2008, 09:37 PM   #2
bjwk89
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It has done that every time for my 2 friends and me, not sure if it's normal but I'm guessing it's common.
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Old 11-28-2008, 09:42 PM   #3
Impreza541
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same with me, it will start on the first try but Ill be cranking for a lil while.
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Old 11-28-2008, 10:08 PM   #4
jt0thevizzle
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Quote:
Originally Posted by Impreza541 View Post
same with me, it will start on the first try but Ill be cranking for a lil while.

Hmmm, yours turn on??? I'm guessing you let it crank for a long while. Mine cranks for a bit(couple seconds) and after that I feel like i'm screwing up the mounts so I just let go and then restart it again and then it turns on easily.
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Old 11-28-2008, 10:11 PM   #5
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Quote:
Originally Posted by jt0thevizzle View Post
Hmmm, yours turn on??? I'm guessing you let it crank for a long while. Mine cranks for a bit(couple seconds) and after that I feel like i'm screwing up the mounts so I just let go and then restart it again and then it turns on easily.
The only thing you are screwing up when cranking the car for to long is the starter.

If your car isn't starting after resetting the ECU I would think the battery just didn't have a good enough charge before you reset it.
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Old 11-28-2008, 10:31 PM   #6
vision.dynamix
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Happens to me all the time. Whether its done by pulling the fuse, disconnecting the battery, a OBDII Tool Reset, or flashing a map, it always takes 2 cranks to start.

With my Legacy, I had a permanent P0420 so I'd leave my ScanGauge connected and reset the ECU while I was driving. Id forget when I came back to my car sometimes, and would be confused why my car wont start..
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Old 11-29-2008, 12:12 AM   #7
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There can be a couple of reasons for this.

First of all, those of you with a DBW setup need to turn the key to ON, then wait for a series of 3 clicks, before cranking the starter.

Second, it's entirely possible you have some small issue, such as a vacuum leak, that the ECU learned around. When you reset the ECU, the learning is cleared, and then engine is now in a state that won't run. Check for things like that.

Finally, don't forget the let the car idle for 10 minutes without ever touching the throttle immediately after an ECU reset.
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Old 11-29-2008, 01:46 AM   #8
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same thing happens to me. i've been driving it for a couple months now and no problems.
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Old 11-29-2008, 02:04 AM   #9
bdon22
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Quote:
Originally Posted by williaty View Post
Finally, don't forget the let the car idle for 10 minutes without ever touching the throttle immediately after an ECU reset.
This is the first time I've ever heard of that...
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Old 11-29-2008, 04:00 AM   #10
RonJitsu
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Happens to me every time. starts right up on the second try.
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Old 11-29-2008, 04:03 AM   #11
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Quote:
Originally Posted by williaty View Post
Finally, don't forget the let the car idle for 10 minutes without ever touching the throttle immediately after an ECU reset.
Hey williaty - I've never heard that before, but it sounds good to me. Whats the logic behind that tho? Does it have to do with the learning function or anything else in particular?
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Old 11-29-2008, 10:30 AM   #12
Jim2752
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Its normal. Try turning the key to the on position without starting the car for 10 seconds. Then try to start it.
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Old 11-29-2008, 10:32 AM   #13
06WRXturbo
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Quote:
Originally Posted by Jim2752 View Post
Try turning the key to the on position without starting the car for 10 seconds. Then try to start it.

+1. that's what I do. starts up right away.
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Old 11-29-2008, 10:52 AM   #14
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Normal after a reset or reflash the car wont start on the first try. Its been happening to me forever now....
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Old 11-29-2008, 11:46 AM   #15
monodark
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i had that problem with my car. when I took it back to subaru to ask them what was wrong with my car they told me that it was normal for the car to do that as the ECU is trying to restart it sell cause you just yanked out its power
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Old 11-29-2008, 01:47 PM   #16
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On most of my ECU resets or battery removals, the first crank doesn't start the car.

After you reset the ECU, the car drives all funny for a while until the ECU relearns everything.
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Old 11-29-2008, 09:02 PM   #17
vision.dynamix
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Quote:
Originally Posted by williaty View Post
Finally, don't forget the let the car idle for 10 minutes without ever touching the throttle immediately after an ECU reset.
Ive been told this, and Ive tried it, but Ive never seen the difference. Ive been known for resetting the ECU while rolling down the highway..
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Old 11-29-2008, 09:05 PM   #18
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It makes quite a bit of difference on our cars. However, it only makes a difference at/near idle.

Idle is controlled by both timing (short term) and throttle opening (long term). The ECU tries to open the throttle to a position that allows the timing to be in the center of its range. Letting the car idle for an extended period of time without touching the accel pedal allows the ECU to get the idle airflow properly learned to zero the timing. If you don't let it do this, it tends to idle unsteadly or feel weird coming away from idle. If you reset it at, say, a stoplight and then try to take off, it'll feel a bit like trying to launch it on a lightweight flywheel where the engine has no interest in keeping running.
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Old 11-30-2008, 03:45 AM   #19
06-wrx-tr
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turn key on 15 sec then try
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Old 11-30-2008, 03:48 AM   #20
CYNCRVR
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happens to me everytime.
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Old 08-10-2018, 08:14 AM   #21
defaultstivaper
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I know this thread is like 20 years old but I did some research and found it. Got my AP last night and will confirm this still happens (even on a new 18 STI). Performed an ECU reset / relearn last night. This morning it took about 10 seconds to start, but did start the first time.
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Old 08-10-2018, 08:59 AM   #22
Charlie-III
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Quote:
Originally Posted by defaultstivaper View Post
I know this thread is like 20 years old but I did some research and found it. Got my AP last night and will confirm this still happens (even on a new 18 STI). Performed an ECU reset / relearn last night. This morning it took about 10 seconds to start, but did start the first time.
On any Subaru I have worked on, if you clear/reset the ECU it pretty much always cranks longer the first time. It needs to see the crank and cam signals run through a few cycles before it fires.
Once started, how it runs is sorta based on how much "parts learning" is needed.
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Old 08-10-2018, 04:01 PM   #23
Dave D.
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I was told by my tuner to turn the key to on, then wait for the cruise control light to turn off. Usually takes 10 seconds or so. After a reset my car starts right up. If I forget, and try to start it right away it will take 2 or 3 tries to start.

Last edited by Dave D.; 08-11-2018 at 02:10 PM.
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Old 08-11-2018, 08:37 PM   #24
Elbert Bass
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When you clear the ECM or disconnect the battery on ANY Subaru with electronic throttle the ECM forgets where wide open and closed throttle is. Before it will allow the engine to start the ECM moves the throttle plate all the way open and then back closed so it will learn what the positional voltages (there are two different ones) are for those two positions. That causes a what is usually a 10 second delay.
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