Idle then dies

Phosoup253 · 05-18-2022, 01:45 AM

Drove my 2005 legacy GT during a rainstorm and car suddenly turned off going uphill after hitting a puddle. Went to crank engine and got nothing. Still have battery power, radio and headlights work. Battery was purchase recently within the year.
The following list are stuff I’ve checked and pass
-fuel pressure
-clean maf
-all fuses are good
-can hear hear fuel pump turn on
-starter

-alternator (failed)

I mentioned rainstorm because I initially thought I hydrolock my engine. As soon as i got towed home, I checked the intake and filter for any type of water and it was dry as can be. Stock factory intake in stock location.
Still convince i potentially hydrolock my engine, I proceeded to pull my spark plugs to see if I have any water inside my cylinder I can purge out by cranking my engine over. Fortunately it crank over, so no bent internals.
I got no water of any sort, very very small amount of liquid which I believe to be fuel on plugs though. Leaking fuel injectors?
Proceeded to do a compression test since plugs were already out and cylinder 2/4 came out 90psi and cylinder 1/3 88psi cold wot.

After reinstalling everything, I decided to give it on more crank in hopes that there was a loose coil or a bad plug connection.
Surprisingly this time around, I did get an idle for half a sec but then it’ll immediately die. If I give about 10-20 secs in between cranks, I’ll get a quick idle then dies.
Back to back cranks leads to no start and no idle like lack of fuel.

I mentioned earlier that the alternator failed. I did not get a new one, i pulled one off of 2002 Wrx that I know was still in working condition because it was less than a year old.

Could it be the alternator from a WRX not have enough juice to power a legacy? Even though they plug right up and fits, I know the part number are different.

Trying to be as thorough and detailed as possible. Any help would be appreciated.

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DrD · 05-20-2022, 11:32 AM

Well, the alternator that came with the 02 WRX is rated at 75A and the one that came with the 05 Legacy is rated at 110A, so there's a sizeable difference, but I would think if the alternator was working, you should not just stall out with the lower output...

benflynn · 05-20-2022, 11:50 AM

Starts, dies repeat sounds like a immobilizer issue

Phosoup253 · 05-21-2022, 12:29 AM

I thought security related too. Going to try and disabled it, think there’s a tutorial somewhere online I seen using factory key.

Car doesn’t idle and dies every crank.
Back to back crank gets no idle.

05-18-2022, 01:45 AM	#1
Phosoup253 Scooby Newbie Member#: 514882 Join Date: May 2020	Idle then dies Drove my 2005 legacy GT during a rainstorm and car suddenly turned off going uphill after hitting a puddle. Went to crank engine and got nothing. Still have battery power, radio and headlights work. Battery was purchase recently within the year. The following list are stuff I’ve checked and pass -fuel pressure -clean maf -all fuses are good -can hear hear fuel pump turn on -starter -alternator (failed) I mentioned rainstorm because I initially thought I hydrolock my engine. As soon as i got towed home, I checked the intake and filter for any type of water and it was dry as can be. Stock factory intake in stock location. Still convince i potentially hydrolock my engine, I proceeded to pull my spark plugs to see if I have any water inside my cylinder I can purge out by cranking my engine over. Fortunately it crank over, so no bent internals. I got no water of any sort, very very small amount of liquid which I believe to be fuel on plugs though. Leaking fuel injectors? Proceeded to do a compression test since plugs were already out and cylinder 2/4 came out 90psi and cylinder 1/3 88psi cold wot. After reinstalling everything, I decided to give it on more crank in hopes that there was a loose coil or a bad plug connection. Surprisingly this time around, I did get an idle for half a sec but then it’ll immediately die. If I give about 10-20 secs in between cranks, I’ll get a quick idle then dies. Back to back cranks leads to no start and no idle like lack of fuel. I mentioned earlier that the alternator failed. I did not get a new one, i pulled one off of 2002 Wrx that I know was still in working condition because it was less than a year old. Could it be the alternator from a WRX not have enough juice to power a legacy? Even though they plug right up and fits, I know the part number are different. Trying to be as thorough and detailed as possible. Any help would be appreciated. * Registered users of the site do not see these ads.

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05-20-2022, 11:32 AM	#2
DrD Scooby Guru Member#: 22412 Join Date: Aug 2002 Chapter/Region: SWIC Location: Albuquerque, NM Vehicle: 2012 Legacy 2.5GT Ice Silver Metallic	Well, the alternator that came with the 02 WRX is rated at 75A and the one that came with the 05 Legacy is rated at 110A, so there's a sizeable difference, but I would think if the alternator was working, you should not just stall out with the lower output...

05-20-2022, 11:50 AM	#3
benflynn Scooby Specialist Member#: 515308 Join Date: Jun 2020	Starts, dies repeat sounds like a immobilizer issue

05-21-2022, 12:29 AM	#4
Phosoup253 Scooby Newbie Member#: 514882 Join Date: May 2020	I thought security related too. Going to try and disabled it, think there’s a tutorial somewhere online I seen using factory key. Car doesn’t idle and dies every crank. Back to back crank gets no idle.