Boost loss issue (EJ20G)

Hi,

I have a 1997 (my96) WRX Wagon, with an EJ20G, TD04 Turbo

Sometimes it will simply never boost further than wastegate pressure (.4bar) but randomly it will correct itself and boost further (hovers around .75-.8bar) nothing excessive.

usually after say, driving up a hill with a small amount of throttle and a little bit of boost it will just drop off for a while, then might come back an hour later. Disconnecting battery makes no difference so I don't think it's limp mode or an error

I had a missifire issue beforehand and assumed that was causing this condition, had replaced all coil packs with the later type ones, and removed the external ignitor. car has had all filters, spark plugs, oil ect and in my opinion running very well (no smoke, smooth acceleration, good vaccum)

I'm suspecting the boost control solenoid? this car has a 3port variant, I have checked the lines, and noticed that the bleed line was missing entirely from the bottom port and into the intake box - not sure if it causes too many issues.

(had initially thought it was a 2 port so had a "restrictor" in the wastegate line, but it was probably placebo that working)

any input or ridiculous claims would be appreciated.

Try giving the boost solenoid a clean out. Put car into test mode(green and black plugs under dash, ignition on/engine off), all solenoids should start pulsing and the fans will click on and off. Then pump some carby cleaner through the solenoid as it opens/closes.

With the recirc hose disconnected, is the hole in the intake pipe blocked off? If left open causes an intake air leak. Also the solenoid is bleeding metered air to atmosphere when boosting. Be best to reconnect it.

 Rosssub said:

Try giving the boost solenoid a clean out. Put car into test mode(green and black plugs under dash, ignition on/engine off), all solenoids should start pulsing and the fans will click on and off. Then pump some carby cleaner through the solenoid as it opens/closes.

With the recirc hose disconnected, is the hole in the intake pipe blocked off? If left open causes an intake air leak. Also the solenoid is bleeding metered air to atmosphere when boosting. Be best to reconnect it.

Will grab some carby cleaner this week and give that a go!, I had used some cleaner in it when I first got the car, but it was MAF cleaner (figured it would clean, without damaging).

I have reattached the Recirc hose, rather keep it all the way the factory intended it!

Have given it a good clean out, using test mode.. still randomly decides it only wants to run WG Pressure? I wonder if there's a seal in there that leaks sometimes? Trying to locate a used alternative at least that way I could pull one apart and see how it works.

Are you running it on 98 petrol ?

still does it on 98 Petrol, I don't think it's an error as you can disconnect the battery and it will still do it.

Sounds like afm issue.. is it running purple? i my have one

.75-.8 would be stock wouldnt it?

Green AFM, .75-.8 is stock yes, around 11~ PSI should be stock. if you account for the boost gauge being innacurate and a little boost creep it's probably spot on when it works properly. (3" Exhaust) 3B ECU "should be 10.55PSI Max dropping to 6,8~ at high RPM"

But the problem is it will just decide randomly to only boost to waste gate pressure, 0.4~bar.

what turbo downpipe do you have? i've had an issue where the wastegate flap was jamming open on the siamese divider of a 3" aftermarket downpipe. took ages to diagnose that..

in case you have an aftermarket downpipe, try removing the circlip, disconnecting the actuator arm from the turbo and check the wastegate arm for bind by hand

Hang on, 3 port boost solenoid... should be 2 port... that could (will) be causiny you some issues

 kamineko']what turbo downpipe do you have? i've had an issue where the wastegate flap was jamming open on the siamese divider of a 3" aftermarket downpipe. took ages to diagnose that..

in case you have an aftermarket downpipe, try removing the circlip, disconnecting the actuator arm from the turbo and check the wastegate arm for bind by hand

Stock, car only has a 3" catback exhaust. (cat still appears to be in place) I might try that anyway

[quote name='kwi_fozze said:

IMG]http://www.scoobypedia.co.uk/uploads/Knowledge/3_port_solenoid_system.jpg[/img]

it's an early car so it has this type.

I think the issue is some one has replaced the lines in the past incorrectly, perhaps there's a bit missing, I don't have a 'reducing' adaptor to go to the compressor wheel for instance.

it was missing the "to inlet post afm" line, but I haven't made another restrictor for it yet, but it hasn't been overboosting.

this is seriously why all old WRX's are ****ed and have boost taps fitted lol.

Fixed, finally... replaced all the BCS lines and started running it on 98. perhaps because it was overboosting sometimes was causing it to not like 95.