1995 Subaru Legacy Gt problems!

[legacygt95]

hey guys any suggestions would be highly appreciated.

I have a 95 Legacy Gt that has been converted to single turbo with a VF29 and has a little issue where boost is cutting as it builds up and engine keeps wanting too stall after a couple seconds on start up.

If I keep revving engine to keep it alive it starts to idle normally after its warmed and been reved a couple times too keep it alive. Also everytime I take the engine out of gear the idle bounces around until it finds itself again.

There is no boost leaks as I have checked everywhere and I got code 66 which I am guessing because I am still running the twin turbo 7C ECU with twin turbo AFM.

Is there anything I have to do with the BBoD?

Im also getting a WRX ECU with green AFM and wanted to know if this would be a suitable setup.

And if I stick to a WRX 4 plug ECU are there any sensors that need to be replaced apart from AFM?

cheers everyone.

Edited August 17, 2016 by legacygt95

[les666]

Have you had a read of this... http://clubsub.org.nz/forum/showthread.php?64-The-Single-Turbo-Conversion-Thread-2-0 I would save trying to get it to run until you have sorted the new ecu and afm and replumbed and rewired the bbod and boost control solenoid cos code 66 can be a ton of things but most likely a boost leak somewhere.

[legacygt95]

That post says it's only applied to the ej20r , and I have the eh20H .

I've been told I could be receiving code 66 as it's still running the twin turbo ECU.

[Rosssub]

Some info on the EJ20H conversion in here:

http://clubsub.org.nz/forum/showthread.php?49062-EJ20H-Single-Turbo-Conversion-Info-please!

Yes you will continue to get code 66 (twin turbocharger fault) running the TT ECU. You could try connecting both sides of the differential pressure sensor to manifold pressure, see if it helps at all until you get the ECU/wiring/BBOD sorted.

[legacygt95]

Thanks heaps, where is differential pressure sensor ? Will try that sometime today

[legacygt95]

Also do both sides of the sensor go into the manifold pressure? Or does one go into manifold pressure and one goes somewhere else?

[Rosssub]

 legacygt95']Thanks heaps, where is differential pressure sensor ? Will try that sometime today

[quote name='legacygt95 said:

Also do both sides of the sensor go into the manifold pressure? Or does one go into manifold pressure and one goes somewhere else?

Should be on the drivers strut tower IIRC, hose #21 and #22 on the BE/BH.

Normally on the TT hose 21 will go to the TMIC to read primary boost. Then hose 22 will go to the secondary turbo outlet to read secondary boost.

You want both hose 21 and 22 to go to the intake manifold, so both sides of the differential pressure sensor see the same pressure/voltage.

[legacygt95]

Thank you so much bro, so I connect both sides of the differential pressure sensor into the intake manifold? Could I connect both sides into a t piece then connect that to intake manifold?

[Rosssub]

Yes could T them together, then a single hose to manifold.

[legacygt95]

Awesome, thanks heaps . Could this be the reason of my problems ? Car wanting too stall on start up etc .

[Rosssub]

Code 66 can cause limp mode so will effect driving/power, but cant effect idle at all. Most likely a vacuum leak or the idle control valve playing up.

[legacygt95]

Could the ECU be sending wrong readings to the engine causing the idle? Because I've checked all hoses and don't think it's s boost leak

[Rosssub]

Sensor's like the coolant temp sensor can effect idle, warm signal when the engine is cold. But more likely a vac leak or a sticky idle control valve, so best to rule them out first. You will see some pic's of the idle control valve in borland667's garage thread linked below. Remove it from the manifold and give it a good clean out with carby cleaner:

http://www.clubsub.org.nz/forum/index.php?/topic/45394-wrx-sti-v3-restoration-project/&page=4

 

To check for boost leaks. With the car idling you can spray ether (starting fluid) around any possible leaks spots. If any fluid gets sucked in the idle will change instantly.

Or block the intake off at the AFM somehow:

 

Then pump 10-15 psi into the intake manifold with an air compressor. Any leaks will show.

[legacygt95]

I'm not getting any Codes for IACV and after I give a couple revs for a minute or two it idles at 800rpm and sits fine. Just is weird on start up and when changing out of gears.

Where are possible hoses that are prone or known for leaking ?

[Rosssub]

The IACV can play up and not throw a CEL (correct voltage feedback, just gunked up). When you button off to change gear the IACV should open instantly (throttle plate closed), so the engine wanting to die when you change gear points to a sticky IACV.

Leaks can have the same sort of symptoms. Split intake in front of the turbo, split breather hose, vac hoses popped off inside the BBOD, leaking BOV, BOV recirc hoses.

[legacygt95]

Engine doesn't really want to die while changing gear just as I take it out of gear it bounces around but doesn't want to stall. Only does that on start up.

I'll clean IACV tomorrow and reconnect the pressure sensor and see if it makes an improvement.

But I'm more then sure that it's not a boost leak as I've checked most of the things you just said but I could be wrong.

[legacygt95]

Do you think it could possibly be coolant temp sensor as my temp gauge on my dashboard takes a unusually long time to rise up to normal temp.

[Rosssub]

 Rosssub said:

Sensor's like the coolant temp sensor can effect idle, warm signal when the engine is cold. But more likely a vac leak or a sticky idle control valve, so best to rule them out first.

IIRC the cluster gauge runs a separate coolant temp sensor on your model.

A bouncing idle, or hunting idle at any temp is most often the IACV.

[legacygt95]

Alsweet, will replace and clean the IACV and see where that takes me. also will reconnect DPS into intake manifold.

[legacygt95]

Hey when i connected DPS into intake manifold car wouldnt start. Where abouts in the intake manifold do I conect it too because theres 4 different holes on the manifold.

[Rosssub]

Hard to say without seeing a pic of your engine due to the unknown single turbo conversion, also depends what has been changed inside the BBOD.

You have possibly disconnected vacuum to the MAP, FPR or left a hose venting (vacuum leak). All hoses need to be connected and not venting.

OEM hose #11 goes to the MAP sensor and is perfect to T into, but the original hose must stay connected: