does EA82T have factory boost leak ?

steptoe · Post by **steptoe** » Thu Jan 01, 2009 8:57 pm

Looking closely at the actual thing, the factory manuals diagrams and text it appears that the EA82T has a built-in factory boost pressure leak. The vacuum that operates the EGR is controlled by an ECU driven solenoid. Designed to bleed off the vacuum as opposed to shut it off when not at correct operating temperature or above 45kph.

This bleed off of the vacuum is bled off to the ducting on the filter side of the turbo where there is no manifold vacuum or pressure (has a tee with the vacuum for charcoal cannister) . I cannot see a one way valve either on the car or in the diagram. To me and my reasoning this is a boost pressure leak ? Have I got something wrong ? Surely this same vacuum source turns to boost as soon as boost is on ?

Why the solenoid and its airline circuit is a bleed off and not an on off set up I don't know. Maybe the solenoid gives better duty when not faced with on off? Who knows? mucu

Gannon · Post by **Gannon** » Thu Jan 01, 2009 10:36 pm

Compared to the large amount of air produced by the turbo, the air that will flow through the tiny pipe is practically zilch. The only reason that the bled air is fed back into the intake is to make it a closed system after the AFM. Saves the computer getting confused. The boost control bleed goes to the same port on the pre turbo intake

steptoe · Post by **steptoe** » Sat Jan 03, 2009 4:24 pm

Point. But...as pressure builds more air is gonna leak back to the turbo intake.

I might try shoving a solenoid valve in place that does simply shut the vacuum OFF and not recirculate it. Still to shove boost vac gauge onto EGR valve vacuum supply to see when it works, compare it to how it is described in the manwell and fill my head with more trivia!

Gannon · Post by **Gannon** » Sun Jan 04, 2009 7:54 am

I wouldnt worry about the small amount of air that will flow through that tiny hose, even at 7psi, you wont even notice it. (the factory bov on a RS liberty leaks 10x what this little hose leaks)

Do you even need the EGR to function properly? Cant you just make it look like it works to keep your inspector happy.

steptoe · Post by **steptoe** » Sun Jan 04, 2009 10:24 am

Man, I am full of it - my memory is failing me. Adjusts medications

RETRACTION AHEAD

looking at the diagrams (beside me as I type) - the Oz turbo efi DOES have a one way valve thingo - non-turb Oz MPFI does not . It appears the 'all others' (as in countries) MPFI also have it whether they are turb or non-turb, EGR or non EGR.

This is in prep for an engineer certificate when it al finally gets into the Brumby not just an RTA inspection.

I hooked up vac/boost gauge to the air line to the egr valve and found that it is not likely to be functioning all that well or correctly if at all in current non loop set-up. The response is that BOOST will reach the EGR valve at all times, whether below the correct temp for it to work or above 45kph speed. The only time any vacuum has shown on the gauge is with the slightest of throttle for just a moment up to about 3 inches of mercury at this is also cold, hot or above 45kph. When I expected to see any vacuum reading it showed ZILCH even when I should have 15 inches. This may be because I don't have the air circuit looped back to intake boot as I think it needs to be linked back to just after my gas mixer. It may be that in non looped the vac or boost forces may stop the solenoid valve operating correctly. Might try connecting a buzzer into the circuit so I can hear if it is getting correct electric signals.

I like the idea of EGR saving exhaust valves or cold egr air giving better economy but only if it totally switches out at speeds above 45

Gannon · Post by **Gannon** » Sun Jan 04, 2009 4:12 pm

I cant see it having much effect on an ea82 as it only affects 2 cylinders anyway.

edit:

Please ignore this post, correction below

steptoe · Post by **steptoe** » Mon Jan 05, 2009 11:03 am

hooked up my spare EGR in cabin so I can observe it during driving (easier than texting , I can just stick my finger in it and feel when its operating) I can confirm the ECU is not controlling the EGR to the limits described in the Subaru manwell as far as cut out when cold or above 45kph.

It functions no matter what the engine temp is or speed. It only opens on the lightest of throttle ( further testing shows between 1 to 10 inHg, higher than 10 is to close off throttle, so TPS must enter into things) , closed on boost, it may actually also close at throttle off with higher vacuum - if that is the case I guess the ECU is preventing open via TPS. I suppose in a way it is still operational - just shut !

Only two cylinders ? I need to look at a spare manifold as I thought it fed back to central plenum.....

UPDATE: so the plan is to be able to hook up the EGR so that it does comply with RTA and applicable ADR's with the LPG as the only fuel and no ECU in the car (planned EA82T into 84 Brumby) I reckon I can do without a cold temp lockout of the EGR as it is only for drivability on petrol (gotta check that one) and can wire up a circuit using the TPS switch as it will be redundanr otherwise so the EGR will switch to closed on no throttle - this is supposed to reduce any reduction in engine braking - leave it functional at closed throttle will allow air to get through EGR

Gannon · Post by **Gannon** » Mon Jan 05, 2009 8:47 pm

Ok, i retract my previous statement

I cant see it having much effect on an ea82 as it only affects 2 cylinders anyway.

I had a look thisarvo and i was quite wrong.
Although the EGR valve is mounted on the passenger side intake runner, it actually feeds into a channel which goes back to the middle of the intake plenum.

steptoe · Post by **steptoe** » Tue Jan 06, 2009 6:01 pm

thinking out loud here helps learn, question and investigate further - staving off alzheimers