Odd issue with GC8 boost solenoid, "ticking"???
 

I think something is wrong with my Factory boost solenoid circuit...

I took the WRX for a drive today, When i stopped at idle.. I could hear a weird constant "ticking" noise.. It's not the injectors.. That's a diffrent ticking noise. It's coming from the boost solenoid... I unpluged it (cable, not the vac lines) and the ticking stopped. You could also touch it and feel it vibrate. (It was quite hot to!)

When i unpluged it there was no change to the car at idle.. It still idled ok.

I presume it's being turned on and off in quick succession... Is it swiched through a relay? Or is the ECU turning in on and off directly? It's never done this before. I don't think it should be doing it eigher..

Any help would be great.

Thanks,

Tim.

OK... It gets power (+ Positive) From the "main relay"... It gets ground (-) from the ECU...

But the power also goes to Oxygen sensor and "pressure exchange solenoid valve". I think that connects to the MAP sensor.. It's on the same metal bracket as the Boost Solenoid.

So it could be the main relay, OR ECU... Does that sound right?

OK.. The power from the main relay also goes to the Idle Control Valve.. So since it idles OK.. and drives ok..

Is it the ECU then?


Tim.

stock ecu?

if so, I would be checking the tubes going to the MAP sensor.

when i had a unichip installed on mine the stock boost solenoid used to tick, lift passenger carpet to check what ecu you have or any piggybacks like a unichip

Interesting..

Fully stock ECU.. I know that (i have pulled up carpet before). I have replaced some tubing for the boost solinoid.. Better go do the map sensor stuff. (It gets super hard and cracks)

The car runs with it unpluged (the boost solinoid)... just very low boost levels AND CEL stays on solid...

Thanks for the ideas..

It hasn't started ticking again today while i drove it...

Tim.

OK.. Changed all vac hoses from MAP/ Boost sensor... all the way to the middle of the inlet manifold. Including the "T" pices. Most of the rubber was hard and brittle. Put good quality silicone hose in. I had already replaced the line from the input duct (Before turbo input) to the Boost solinoid.

Unfortunalty.. It hasn't changed anything... After a test drive around the block.. Boost level is fine.. But boost solinoid keeps "ticking" on off, on off, etc...

Any ideas? Maybe replace "main" relay or ECU? They are the only 2 things that control it.

Tim.

its meant to tick

[QUOTE=thrashed2010;741004]its meant to tick[/QUOTE]

Are you sure? I would think if it was meant to always do that.. It would always do it. But it has only just started to do it. None of my other subarus do it eigher.

I'm guessing this is probably how they get over hot and the glue ends up running out of the top.

Tim

Replaced main relay. No change.. But no surprise there though... I thought it was ok. Pain to get to!

Can you change over the MAP sensor?

Maybe... It is boosting ok.... I'll have to check part numbers. I thougt a WRX was a 2 or 2.5 BAR sensor... Were as a STI is 3 BAR... If that's true... Then i don't have a spare wrx one.

Subaru says it shouldn't be "ticking" like it is.. I'm going to swap ECU next week...

Tim.

If you swap the ECU and it still persists...
Possibility of an intermittent wiring issue? i.e. loose/poorly connected wire somewhere.

[QUOTE=Soksta;741159]If you swap the ECU and it still persists...
Possibility of an intermittent wiring issue? i.e. loose/poorly connected wire somewhere.[/QUOTE]


Thought about that too. If you unplug the boost solinoid.. The CEL comes on. I would hope if there was a doggy connection.. that would happen when it's pluged in. The connector were it plugs to the harness is fine. The pins are clean.

If i have to rewire from main realy to solinoid.. You would almost have to take the dash out to get to that relay. I was only able to get my hand to it.. That doesn't include a wire and a soldeing iron...

Also if it was a wire.. i thought it would start doing it the moment you turn the car on... It doesn't untill you drive the car for a bit.

I'll put another map sensor in tomorrow and see what happnes...

I think wire test would have to be straight to the battery (+) then the straight to the ECU (-).. That sounds doable..

Just had another look at the GC8 tech manual. It says the output pin (from ECU) to the boost solenoid should be 10V to 13V at idle and when ignition is ON (But engine off). That seams like an easy test. But does that "idle" mean when ever the car is at idle.. or only when you start it up for the first time??

That should mean that both pins should be the same voltage (One from + main relay), The other side from ECU.

Will check tomorrow.

Well i'm reading 0V at "on" (engine off). and 0V at Engine idle.. Any one else what to unplug there boost solenoid plug and measure the Black with white striped wired pin?

I check the pressure exchange valve too.. same result.. But it's meant to be 13V too.. wonder if the manual could be wrong...

Replaced main relay, Replaced MAP sensor, Replaced map sensor hoses, Replaced boost solenoid, Checked wiring between plug and ECU end,

Everything passes / or makes no change. Only thing left is ECU...

Have you reset the ecu? (ie Disconnect battery) I occasionally get the clicking in my 97 wrx too. I find that it also brings the idle up a few hundred rpm as well.

is it ticking at idle ?

Yep, Ticking at idle. It never did that before untill now.

Well got ECU replaced today . And no more ticking yet. Have gone on several drives.. So i'm hoping that was it!

T.

[QUOTE=dtp31;743000]Well got ECU replaced today . And no more ticking yet. Have gone on several drives.. So i'm hoping that was it!

T.[/QUOTE]

Did you actually try resetting your old ecu first before putting in the new one?

Not by plugging the, i think, green connectors together. The ecu had been unpluged a few times...