Hello,

My '96 Subaru Legacy 2.2L has been giving me trouble with it's egr system for quite some time. I and my mechanic have cleaned everything several times, but it keeps bringing up the CEL after a few days when I clear the codes. This is always preceded with the car kicking, especially at highway speeds. After the check engine light comes on, the car drives just fine (perhaps gets slightly worse gas mileage...) Anyway, I'm fairly sure that something needs to be replaced, but I'm not sure what. How do I test to see what component of the EGR system is malfunctioning, so that it can be replaced? Any help is greatly appriciated.

Hello,

My '96 Subaru Legacy 2.2L has been giving me trouble with it's egr system for quite some time. I and my mechanic have cleaned everything several times, but it keeps bringing up the CEL after a few days when I clear the codes. This is always preceded with the car kicking, especially at highway speeds. After the check engine light comes on, the car drives just fine (perhaps gets slightly worse gas mileage...) Anyway, I'm fairly sure that something needs to be replaced, but I'm not sure what. How do I test to see what component of the EGR system is malfunctioning, so that it can be replaced? Any help is greatly appriciated.

Things to check:

1) EGR Valve itself

 

2) BPT (Back Pressure Transducer)

 

3) EGR Solenoid

 

4) Condition of vacuum hoses between the throttle body, BPT, EGR Valve and Solenoid

 

BTW, this is for a 2.5EJ, so I don't know of the similarities, or differences, of the EGR systems btween the 2 engines. I assume they are similar.

 

I assume also you and your mechanic have checked the operation of the EGR valve - basic. Once the engine is warmed-up, you should be able to rev the engine by hand at the throttle body, observe if the EGR valve is opening above 2K rpm and closing at idle (not sticking). Does it hold a vacuum test?

 

I'd changed the vacuum lines first, since they're an inexpensive and quick replacement. Then move on to replacing the BPT - I've never found any info on how to test/check this qizmo, though I'm sure there must be some type of vacuum measurements that could be done. If memory serves me, the BPT is around $50. Oh, and make sure there is no moisture in the vacuum lines, or the BPT also - that can cause CELs, my mechanic says moisture was my culprit, and it eventually solved my EGR woes.

 

Anyone else add-to or correct me on the above?

 

 

Paul

What is the code that is being set?

What is the code that is being set?

P0400. The EGR valve itself appears to be working properly (and holding vacuum...), and the hoses are clean. I'm gonna try replacing all of them, because the ends seem a little worn , and may be leaking vacuum. After that, I guess it's between the solenoid and the backpressure transducter. Anybody know a good way to test which one it may be? Thanks in advance.

On the passanger side strut tower there is a MAP sensor with a vacuum hose going to the intake manifold. In this vacuum line is a filter, look at the enige it will be to the left of the throttle body on the back side of the intake. Part # 22663AA010. Replace that.

 

The computer monitors EGR flow by the change in manifold air pressure. This filter being restricted throws off the prussure that the MAP sensor sees.

WAWalker,

 

Is that the small round shaped drum with the foam edging? My '96 still has it's orginal, the foam is actually crumbling from age. Good to know if the P0400 ever shows up again, but I may replace it anyways due to age and condition.

 

Thanks for that info.

Paul

WAWalker,

 

Is that the small round shaped drum with the foam edging? My '96 still has it's orginal, the foam is actually crumbling from age. Good to know if the P0400 ever shows up again, but I may replace it anyways due to age and condition.

 

Thanks for that info.

Paul

That is the one.

On my 97 OB, the MAP sensor that Walker speaks of had actually failed. It "checks" the EGR by looking for a pressure (vacuum) change when the EGR is triggered. Hence, I was getting the P0400 code, even though nothing was actually wrong with the EGR circuit.

 

My only other symptom was a slight delay in shifting (automatic). The sensor feeds data to the TCU as part of its shift algorithms I was told.

 

Once the sensor was replaced (darn expensive thing too), both problems went away.

 

About 1.5 year later, I got the EGR code again. They changed the BPT since the diaphram was torn. No luck. Changed the solenoid and now everything is fine. Note - that little filter was changed somewhere along the line... with the sensor I think.

 

Commuter

A mechanic at Suburb Service told me that some of the 96 and 97 2.2L had single exhaust ports instead of dual, and that they heat up too much. Then the sliders for the exhaust valves get messed up (from the heat). He said that to really fix it you have to replace the cylinder heads. (ouch) My 96 2.2L seems to be having the same series of symptoms. When I get my axle replaced and my oil changed next week he's also gonna check for the single port exhaust valve problem. He thought that might be the root cause of all the weird things that are going on with my Legacy.

On my 97 OB, the MAP sensor that Walker speaks of had actually failed. It "checks" the EGR by looking for a pressure (vacuum) change when the EGR is triggered. Hence, I was getting the P0400 code, even though nothing was actually wrong with the EGR circuit.

 

My only other symptom was a slight delay in shifting (automatic). The sensor feeds data to the TCU as part of its shift algorithms I was told.

 

Once the sensor was replaced (darn expensive thing too), both problems went away.

 

About 1.5 year later, I got the EGR code again. They changed the BPT since the diaphram was torn. No luck. Changed the solenoid and now everything is fine. Note - that little filter was changed somewhere along the line... with the sensor I think.

 

Commuter

Ouch! If the MAP was bad there should have been a code for it. If there was only a P0400 code and they replaced the MAP sensor and filter at the same time.................you my have bought a MAP sensor for nothing. Have only see one bad MAP sensor in the last 8 years.