My legacy starts and runs a few seconds and dies

[Nikola05]

I have a problem with my legacy and if someone could help me l would epriciate it.

I bougt the car like this. The previous owner said he drove it home one day left it over night and in the morning he started it and it shut of.

So the car starts runs perfectly idels and revs in 10 to 15 seconds of working and shuts of. I found out it loses power to the incectors and shuts of, so l changed the crank sensor and timing sensor and the fuel pump and MAS sensor didnt make a diference l also tried just a diferent ignition key and lock and its the same.

So if enyone knows something l dont it would be very epriciated.

Thanks in advance.

[doublechaz]

Mine did that once after I did some work on it.  When I buttoned up I missed connecting a half inch vacuum line.  It let in so much air that the ECU would panic and shut down just like you describe.  Run perfect long enough to back out, and then shut down.  Start right back run perfect same amount and shut down.  I believe it did not set any codes when I went through this.

 

Perhaps the PO had a rodent get in there and open something up real bad.  Perhaps the extra vibration as it shuts down tore the main induction tube.  Perhaps the PCV stuck wide open after that shutdown and there is a problem elsewhere letting air into the crank case.

[googlydratini]

Mine is doing the same after i put the motor back in. I hope it's something as simple as this when i decide to dive back into it.

[Nikola05]

On 4/1/2023 at 5:09 AM, doublechaz said:

Mine did that once after I did some work on it.  When I buttoned up I missed connecting a half inch vacuum line.  It let in so much air that the ECU would panic and shut down just like you describe.  Run perfect long enough to back out, and then shut down.  Start right back run perfect same amount and shut down.  I believe it did not set any codes when I went through this.

 

Perhaps the PO had a rodent get in there and open something up real bad.  Perhaps the extra vibration as it shuts down tore the main induction tube.  Perhaps the PCV stuck wide open after that shutdown and there is a problem elsewhere letting air into the crank case.

Thank you for the advice l looked at every thing and it all looks good.But l drove it to my local mecanichs and they dont now what it is,and electicians. Some of the electricians told me it could be the key code got lost or the ecu doesent recognise it.

[doublechaz]

My second gen doesn't have an electronic key code.  I didn't know any of them had that until later.

 

We should be able to rule out crank sensor as it won't run without that.  Clearly you are getting fuel and spark.  How long does it run before giving up?  Mine was just long enough that two tries got me out of my garage bay and partly turned.  Certainly no where near long enough to drive it down to the mechanic.  Maybe 10 seconds.  I think I got it back in the garage in one try because I knew the pattern by then.  Only took minutes to find the problem once I looked at the items I had touched before it started acting up.  If I remember right it was the big vacuum line from the valve covers to the bottom of the intake after the MAF and before the throttle plate.

At this age you could get a leak that bad on a large vacuum line from dry cracking and it might not be visible.  It might take flexing the line to bend open the crack.  I once had a car where the flexible part of the intake itself did this.  It would only stall when stopped at a light and the engine torque against the brakes leaned the engine.