1999 Subaru Legacy 30th anniversary edition 

5 speed MT 

ej22

 

Car starts, runs for a few seconds, then dies, will not idle. With proper TPS adjustments car runs without MAF connected, but dies as soon as it's plugged in. Car ran perfectly healthy until I replaced coolant temp sensor, tried putting old sensor back in, did not help. Tried pumping gas while starting car, caused motor to sputter,buck and die.

 

Whats new: 

MAF (has been replaced three times over the course of two weeks)

TPS 

PCV valve 

Hoses that connect to the PCV from the torque box 

Battery 

Thermostat 

Coolant temp sensor 

 

What's been tested:

Fuel pressure within spec 

gets spark 

gets fuel

All sensors have been back tasted and are receiving and putting out the proper amount of electricity. 

Smoke tested for vacuum leaks (there were none)

 

I have absolutely no idea what could be wrong, after the extensive amounts of diagnosis I'm at a standstill. Any suggestions would be appreciated.

Edited April 3, 20187 yr by Multisurface-Legacy

Has an air leak between the MAF and the throttle body.

Did this start suddenly or after doing some work?

 

Which "Proper" TPS adjustments? Anything except the factory setting is improper. TPS is critical for the ECU to determine idle speed and idle air fuel ratio.

In addition to a possible air leak between the MAF and throttle body, you could have a bad intake manifold gasket or even a cracked intake manifold.  Other possibilities include a vacuum hose disconnected, major break in a vacuum line, especially the one to the brake booster or a bad brake booster.

 

But, I would first disconnect the battery overnight, or even for up to 24 hours, then reconnect everything and restart the engine.  Give it a chance to learn the new MAF sensor.

Has an air leak between the MAF and the throttle body.

Did this start suddenly or after doing some work?

 

Which "Proper" TPS adjustments? Anything except the factory setting is improper. TPS is critical for the ECU to determine idle speed and idle air fuel ratio.

"Proper" TPS adjustment means adjusting the new TPS to the factory setting. As can be read in the original post, I smoked the system to check for vacuum leaks, there are none. This began after changing the coolant temp sensor, I tried putting the old sensor back in, there was no change. Car still starts,  but dies immediately. 

In addition to a possible air leak between the MAF and throttle body, you could have a bad intake manifold gasket or even a cracked intake manifold.  Other possibilities include a vacuum hose disconnected, major break in a vacuum line, especially the one to the brake booster or a bad brake booster.

 

But, I would first disconnect the battery overnight, or even for up to 24 hours, then reconnect everything and restart the engine.  Give it a chance to learn the new MAF sensor.

I have disconnected and reconnected the battery in this manor at least ten times whilst trying to fix this problem, I smoked the system and discovered no vacuum leaks. 

99 legacy (with 2.2, not outback) has the weird double air box setup.

 

I will bet that the second air box (long one) is probably not sealed tightly.  It's often difficult to get the bottom tabs fully engaged and the whole unit tightly sealed.

 

Take the box off and get it completely sealed, then install back onto the engine.

 

$20 bucks say's that's yer problem.

What Gloyale said or one of the hoses for the PCV/ breather tubes near the back corner of the bell housing might have broken or isn't connected properly.

What Gloyale said or one of the hoses for the PCV/ breather tubes near the back corner of the bell housing might have broken or isn't connected properly.

I'm intrigued by Gloyale, will have to try that

I replaced both the PCV and the y shaped configuration of hoses that connects to it. 

99 legacy (with 2.2, not outback) has the weird double air box setup.

 

I will bet that the second air box (long one) is probably not sealed tightly.  It's often difficult to get the bottom tabs fully engaged and the whole unit tightly sealed.

 

Take the box off and get it completely sealed, then install back onto the engine.

 

$20 bucks say's that's yer problem.

I have not tried this but it seems very plausible, would you recommend replacing the air filters? I know they have a rubber sort of setting around them, could that help the box seal? Any suggestions on what to seal it with? I don't recall there being a gasket.  

The filters seals up the air box pretty good.  

I have replaced the newer style double airbox with the older 90-95 intake tube.  It works well on the 2.2 swaps.  

I have not tried this but it seems very plausible, would you recommend replacing the air filters? I know they have a rubber sort of setting around them, could that help the box seal? Any suggestions on what to seal it with? I don't recall there being a gasket.  

no gasket.  Just a good air filter should work.