ECU code 35 on a 1985 EA82T engine.

[gbacon67]

I have an ECU code 35.  Past posts indicate this is for a "purge solenoid valve".  Is the item below the purge valve?

 

[Steptoe's photos]

3-5 OK, where did you find this soleniod? I don't recognise it as a Subaru item but may have been upgraded at some stage or is US DM specific. About the only thing that gets 'purged' is the charcoal cannister. Can you simply add power and ground to the terminals and see a change between flow and no flow? Some solenoids vent to atmosphere, some allow path to be cut and opened. You could also test the loom side of the plug to see what you get on DMM with IGN ON and RUNNING. The moment I got my first 85 turbo up and running - it had a n error code that was similar looking solenoid designated for EGR vacuum supply. Error was " stick to open or close" . A quick test to power it up found it not cooperating, either shorted inside or just pooped. I found same item on a carby model, others have used Toyota for a parts source for these. Fixed once, never gave trouble again. Don't forget those photos of your aircraft !

 

[gbacon67]

Thanks for the help Steptoe.  This solenoid is connected to the manifold pressure tubing.  The wiring goes into the ECU.  The builder, now deceased, provided a lot of extra parts when I purchased the project plane.  The pic I attached is a spare, but looks identical to the solenoid that is installed.  It's possible the solenoid pictured is not a vapor purge valve.  It may be a vacuum solenoid used for another purpose.  It's also possible, the builder completely omitted the vapor purge valve as it isn't needed in the aircraft.  

No, I have not yet began troubleshooting and tinkering with the wiring.  I don't want to risk burning up a part that may be working correctly.  Attached are photos of the Pietenpol Aircamper with the EA82T engine.  The builder selected the EA82T due to his home field elevation, 7,500 ft!  The turbo really helps performance in this thin air environment.

[DaveT]

Note that the ecu code 35 is only an indication that the solenoid coil is open or maybe shorted. (I have only seen them fail open) The ECU is not very smart on this era engines, if you connect a resistor in its place, it will think it is fine.

[gbacon67]

Thanks Dave.  I should be able to fine the ECU pinout in the shop manual, correct?

[DaveT]

I know the factory service manuals have full wiring diagrams, pinouts, etc.

[Steptoe's photos]

Thanks for the photo's . I need to look at them in a better lighting environment to study a little more. What Dave said above, about shoving a resistor across the loom side plug terminals has been a common suggestion over the years. I have never had to do this myself. Even plugging a healthy one in place should fix without trying to work out a resistor value to use. The manuals have a very good ECU pin out chart. Yeah ECU controlled.

[gbacon67]

I'm wondering if the item in the original post photo is a pressure transducer for manifold pressure.  My understanding is the timing is controlled by the ECU differently at the boost pressure increases.  Now, finding a functioning vapor purge solenoid may be a difficult task.  Thanks again for the help!

[DaveT]

On my non turbo EA82s, for purge solenoids, and the egr solenoid,  I use Toyota solenoids.   Almost every Subaru solenoid I have ever had has died.  I am still using the same Toyota ones I got at a scrap yard in 1989.   I've had about 7 of these cars over the time from 1988 til present.  I don't know what model the solenoids were removed from, but it was a similar age as the car, so late 80s.  They are not unique, so it doesn't  matter.   3 ports, just have to test.which are equivalent function, replace the connector with the one off the dead subaru solenoid. 

[Steptoe's photos]

There we go, the Toyota hybridder enters the room

GBA , don't overthink these most basic fuelies. They did not use manifold pressure for much ECU input. There is an overboost pressure switch designed to have ECU cut injectors around 9 psi boost. Next to it is another similar looking switch to get a green glow on a dash light to indicate turbo is starting to spool up - comes on about 2 psi. It may also start to over ride O2 sensor control to enrich for boost load.

 

If it is truly the 3 plug ECU controlled EA82T from 1985 it's ECU won't have anything to do with the timing delivery or advance, that only happened with the 4 plug ECU 87model year and onwards. They got hot wire air flow meters, we three pluggers got a flapper style AFM and a completely independent spark system with a vacuum cannister on the side of the dizzy. If you rely on this off the ground and have vac can, can't hurt to test it for operation. It does spark advance and boost retard and ands a crisper drive when working. I have had many with holes, and even last year, blew a new hole in my new to me from Subaru in Japan 13 years earlier. Just as well you don't run craft on propane. I do, but safely on the ground. To get boost pressure of propane mix sneak through small hole in that diaphragm - then ignite from spark jumping about inside the cap - KABOOM - massive backfire (possibly in your pants too  )

Edited September 17, 2022 by Steptoe's photos

[scoobydube]

On my 86T, that is one of two identical vacuum/suction devices that keep all of the other suction dependent devices functioning, such as the 4WD shifter as I recall.  If your 4WD shifter goes out, this is the first thing that you check.  The two vacuum/ suction devices are located directly behind the Turbo air filter assembly, on the engine right side of the car.  They can become unplugged and therefore stop your 4WD from shifting, or you can break off that male tube extension that the hose is pushed over.  I had one go out completely at maybe 350,000 miles. All of the suction gismos on top of the engine, are connected to that sucker.  The distributor advance suction hose is independent of this system because it is a variable suction to the distributor.