Rex01

Hi,

I have a standard (for the moment) WRX 05 plate, with 50k on it. It's recently started intermittently softly cutting power at 6k RPM in 3rd and 4th, as in it just seems to stop pulling and doesn't want to rev any further on WOT. There's no harsh cut out per se, it just sort of stops revving.

I bought an OBDLink LX to try and see a bit more about what's going on and I can see that when this occurs the boost target seems to be getting cut. Once it's happened the car will only sustain about 9psi in 3rd and 7-8psi in 2nd. If I switch it off and come back to it all is normal again...

It's currently got some bg44k in the fuel which seems to have helped it a bit, but the problem persists. I've been keeping an eye on timing advance, boost and MAF volume and can't see anything that helps me figure out what's up.

My guess is it's fuel demand related due to it only happening on WOT at max load, but I'm struggling to get any meaningful logs that help me.

So, can anyone advise what I should be logging and with which tool? I've come to the conclusion the phone apps aren't comprehensive enough to help here (please feel free to correct me) but the Windows OBDWiz thing that came with the OBD2 dongle doesn't seem too brilliant either.

Frustrating - I just got a straight through system for it (not fitted) and was about to get it remapped, but I need to fix this first

Any thoughts very gratefully received!

*edit* - should add there are no fault codes being logged on the ECU.

Rex01

So - the drive home this evening saw me hit peak boost of 15psi... I'm pretty sure this is over the standard target boost. I'm wondering if I might have some sort of leak on the downpipe or something to allow the turbo to boost that high? Is that feasible? I'm sure I've read that the reason a remap is essential after decatting is due to overboost, so would a blowing exhaust give the same symptoms (if milder)?

Rex01

Problem still persists, but I think I've got to a point where it's repeatable. I've checked all the exhaust from turbo back and found no issues. Cleaned the BCS, checked all the pipe work around the intercooler etc and found nothing obviously split. Running out of ideas! It's been overboosting quite badly, hitting 17psi at one stage, but since cleaning the bcs that's gone away and I'm now back to it cutting boost to 8psi. It'll run up to the redline in 3rd at 13.5psi, gets upset in 4th and drops to 8psi and won't boost past that until the car is switched off and on again.

Any ideas?

Rex01

To anyone who isn't getting a response, NASOIC has some active and knowledgeable people. I appreciate I may have asked the wrong question, and don't want to be negative about scoobynet (nor should I expect people to give their time so freely) , but 0 responses? Draw your own conclusions.

Thanks to all those that took the time to read. Think time might be better spent elsewhere! Now to see if I can remove my account.

ZaKv1

iTrader: (8)

you only had 163 views, stick a tampon in and be patient you will get help

have you checked the restrictor pill ?

mine went walkabouts and I was hitting 1.6-1.9bar and getting fuel cut

I made one from a mig weld tip and it did the job, I was back at 1.2bar like it should have been..

also is your car fully standard , any mods atall?

Noz_13

Tactrix cable & Romraider Logger is your best bet if you haven't diagnosed the issue yet. Sounds like a load-related issue, there is no per gear boost compensation on a stock 05 WRX map.

When similar happened on my WRX PPP (ECU now unlocked & mapped thank God), I had a code that lasted for 3 engine starts (along with reduced boost until the engine was restarted once) due to boost exceeding the limit for a prolonged period. This happened at high load, low RPM. Once I adjusted the limits with appropriate mapping, no more codes.

I would suggest getting it mapped but inform them beforehand there could be boost control issues

Rex01

Lol! Ok, harsh but fair

It's completely standard mate. Couple of the guys on another forum have suggested that it's likely DAM related which makes sense. I'm getting a vagcom cable off a mate so as I can track IAM/DAM to see if knock is the problem. The Obdlink is great, but no ssm which was my newbie mistake.

It overheated briefly recently after a failed radiator hose, I mean pootling along at 30 and temp gauge rose to 3/4's, I stopped and didn't run the car again until it had water in it, but still, ally block and such... I have suspicions anyway. Tbh, it's been a couple of months so I thought no damage done, but who knows?

Rex01

Really? Go for the map now? Seems brave without knowing the fault?

I'm happy to take advice, and very appreciative of people's input (despite my petulant post) - but shouldn't it run right before I mod it?

I'm not getting any cel or fault codes so I'm confused by the issue. Worried it might be something more sinister tbh. Seems to me like the ecu is getting mardie about something it sees and maybe bleeding boost as a result. Odd that it always drops to 8psi, seems like some sort of safety measure? I'll get rom raider going with something that supports ssm and report back.

Apologies again for being a little girl about the lack of feedback, was feeling like a fat bird on prom night, sat by the phone, nobody calls... lol!

Noz_13

If they're informed there is an issue, they will fully diagnose it before mapping.

Depends if you want to be messing around with it yourself, or have it diagnsoed, fixed & mapped (in an ideal world, of course).

Rex01

Fair point. I've got a turbo back decat to go on it before the remap, was just worried I'd be changing too many things at once to make the remap sensible, particularly since its playing up? What if it ends up being a compression issue for example, the mapper would be wasting his time (and far more importantly, my cash lol).

On that subject, what's worth doing intake wise other than filter? Is it worth going cai? I like my fogs!

If I end up with a dead scoob I have to drive my Vito all the time, so don't want to kill it! The van is great for trips to the dump, but not quite the look I was going for...

Noz_13

Cover the basics such as a compression test, correct plugs, etc etc.

If you're struggling with diagnosing an issue to the point you're getting vexed with a forum and need to buy equipment, plus it is going on 7 weeks since you first posted, isn't it time to have it looked at properly so you can move forward with it?

Your call

Rex01

That's again fair comment. I did want to fix it myself, bit stubborn/stupid maybe, but was hoping it would be something I could learn enough to diagnose.

Oh well, maybe it's time to put my hand in my pocket and pay a professional.

Appreciate your time in replying. Thanks.

ZaKv1

iTrader: (8)

if it was me I would check the restrictor pill first, make sure you have one in and nothing is blocking it ..
then it would be
boost pipes
check the turbo actuators isn't stuck
boost solenoid
maf


if all fails I would take it to a specialist..


good luck, let us know what it was when you sort it

bludgod

iTrader: (3)

if you have a vagcom or tactrix cable you can use the romraider logger software to check the long term trims/stored values in the ECU. This will immediately show you if you have a leak somewhere or if your engine is pulling large amounts of timing due to knock.

When the IAM (or DAM as you've called it) drops low enough, the bcs is disabled so you get spring pressure boost only until things are reset.

ScottyPPP

Where in Hampshire are you? I've got a cable and romraider logger.