David__H

I have a Hawk STi which was remapped some years back to around 350bhp, running around 1.4 bar boost. Everything has been fine with it, but driving today I glanced over at the boost gauge under full power and it's only holding about 1 bar boost and it does feel slow.

I can't understand what's happened. The car is pulling cleanly and the boost is well controlled, so I'd imagine it's not a boost leak?

Is it possible for a mapping to be "lost" and the car revert to stock? There's no CEL warning light and no codes on my OBD II reader.

JDM_Stig

iTrader: (3)

Lol lol lol, did you leave the cover off your ecu and it escaped?

Reset the ecu, put decent fuel in and see what happens.

debbiesonic

iTrader: (7)

Was it mapped with 2 switchable settings I.e low & high? You may have inadvertently switched it back to the low setting.

David__H

I only run V power, ever, so the problem shouldn't be fuel.

I checked the IC connections and the thread is buggered on one side of the dump valve mounting points and won't torque to the required amount (11.6 lb ft). Guess it could be leaking the air at high boost?

Coming back to the ECU, does a remap overwrite the stock map, i.e. a reset wouldn't do anything to the remap?

Thanks

David__H

It's running on the subaru ECU, so I presume there is no functionality to switch between maps like you could on an aftermarket ECU?

peter zippy reid

iTrader: (25)

Have you had battery disconnected or fault code as could be running low boost map
When andy forrest maps theres 2 boost levels controlled by presseing rear demister button

RAGGY DOO

iTrader: (1)

Post of the month lol

David__H

It does feel as if it's running a low boost map. However, having had the car for 2 years, I've not noticed anything like it before. The settings on the dash were as I usually have them.

debbiesonic

iTrader: (7)

The standard new age ecu's do have the functionality, quite often set up for the rear demister switch to alternate maps (as said above) iirc the sequence is throttle pedal down when switching ignition on.
Or it may have an aftermarket switch fitted somewhere.

fpan

iTrader: (11)

Did you press the rear demister button while the throttle pedal was pressed to the floor and the key was at the second position of the ignition?

Does it always boost to 1 bar regardless of gear now?

David__H

Just been out in the car and done a load of tests. I've tried switching the ignition off, depressing the throttle to the floor, switching the ignition to position 2 and pressing the demister, followed by starting the car and testing it. Doesn't appear to make any difference at all.

I might add, it's not clear whether the twin boost-limit facility is actually on the UK cars. Some say it was only the earlier newage cars only (blob and bug), some say JDM only. However, the ECUtek maps that are offered may well have this available, depending on the customer requirements. Sadly, I have no details of the remap that was done on my car (I know it's safe since I had it checked on the rollers when I got the car). Anyway, after testing, I think we're barking up the wrong tree.

I've now tested peak boost in 2nd, 3rd and 4th. It varies a little, as you might expect. In 2nd and 3rd the boost builds quickly to a slight overshoot of 1.2 bar, but then pulls back to 1.1 bar. In 4th the boost builds more slowly so there is no overshoot.

According to my DEFI, the peak boost I've recorded previously is just shy of 1.4 bar. I know it hit 1.35 fairly regularly since I had to increase the warning limit on the gauge from 1.35 to 1.4. Therefore I'm pretty sure I'm not getting the same boost levels as before, but admittedly, I'm only missing about 0.2 bar (which does make a fair difference).

Don't think the IC connections are leaking. Wondering if I should try cleaning the boost control solenoid...

bludgod

iTrader: (3)

hawk sti can have two full maps on ecutek if you want. Procedure to switch is either:

ignition on
full throttle
press defogger

OR

whilst driving, 100% throttle, press defogger

In either case, if there is a map switch enabled you'll see the engine light flashing to confirm the change of map. No flashy means no map switch.

If it's not a switched map then next job is to scan for fault codes (historic or active) and see where that points you.

David__H

Not a switched map then. And no codes logged.

David__H

The guys at TFS way overfilled my car when they did an oil change in November. I think a lot of it was making it's way into the intake via the PCV. Perhaps cleaning out all the vacuum pipes and the solenoid with brake cleaner would be the next thing to do:

Tis mentioned here with a good result obtained.

http://www.subaru-impreza.org/forum/...-cleaning.html

The Trooper 1815

iTrader: (31)

Two problems I would kick myself for if I were you.

1. Not regularly checking the oil on a 2.5 STi engine.
2. TFS need a good spanking and a by pass next time the car is due an oil change or just do it yourself.

David__H

Yup on both accounts. I've twice found the oil level right at the bottom of the dipstick below the low level. These days I check it frequently and record when I add oil. She's a thirsty engine.

And there's no excuse for sloppy oil changes, especially on our cars. Back to Len at Subaru4You for all future garage work. He's not local, but I trust him with the car.

Don Clark

Mine originally was a thirsty 2.5 but was "cured" after fitting an AOS system

Give Daniel a try at Surrey Subaru Specialists in Camberley.
https://www.facebook.com/pg/surrey.s...=page_internal

Linksfahrer

I think you could be right to look for a boost leak, or even oil fouling.


My 2005 WRX has a JGM mapped 16G.


A while ago my boost level dropped back from its original 1,2 to under 0,9 and did not change even after I switched between twin map using throttle full / demist, ( my lower map calls for 1.0) All of which made no sense to me, until I discovered a boost leak that was in the middle joint of my decat uppipe. So I welded it up again and everything is back to normal.


Looking at your symptoms and road test , You should expect that your mapper will protect the engine in 5th gear and at higher revs so Id expect boost to tail off accordingly.


However during the road mapping Simon had also found oil in my Intercooler , which was cause of knock and a (timing pulled) hestitation every time we repeated the road test circuit on a tight 2nd gear right hander.


Oil collected in one side of my intercooler and every time we pulled max G some of it would enter the throttle , then the map would realise something is wrong and start taking measures to protect the engine. Pulling Boost and Timing.


So if your car is using quiet a bit of oil, and you will see it in the intercooler at the junction to the throttle body then you might want to get a oil catch system fitted.


Who knows this might be your problem on boost.


Best regs Linksfahrer

The Trooper 1815

iTrader: (31)

Post 14.

Linksfahrer

Yeah , Simon had the restrictor out as well. I remember he just took a clean one from the box of spares he carried. But when were still not getting
the anticipated boost, that's when he had the IC off.

David__H

I was looking at catch cans a while back. Did quite a lot of research on the reasons for PCV systems. Turns out there are downsides in terms of not drawing the air from the engine crank case (under normal driving there is a vacuum in the intake - this draws the stale air out from the casing, which if left in there is not good for the engine). Off the back of that I decided not to do the mod. But I would accept my engine would run much cleaner!

David__H

AOS? Return to sump catch can system?

Don Clark

Yep
Air Oil Separator

joz8968

iTrader: (13)

Just as well!

https://www.aossystems.com/product3.htm#wall5

Tidgy

duff maf maybe? may been suggested already

David__H

I found that. You fitted a urinal to your car and it fixed the problem.....

David__H

Anyways, I've now checked the vacuum pipes from the turbo and wastegate actuator that go to the boost solenoid. All in good condition. Cleaned them out with brake cleaner, but it seems they were clean. I could see through the restrictor pill in one of the pipes near the T-piece, so all seems fine. I haven't tested the solenoid yet, but I'd expect if it wasn't working i'd have a fault code???

Will probably pull the IC and check everything. I've bought a new gasket for the dump valve attachment and two new bolts. I think one of the attachments needs a helicoil, but I'm worried about swarf getting into the IC and being drawn into the engine.

little'un

iTrader: (9)

Smoke or pressure test the inlet for leaks would be a good idea.