Ash Webster

I know this topic has been done to the death on here, but i can't seem to get a proper answer anywhere, and there are various factors that could be affecting my boost.

Symptoms
Car will run at ~0.7Bar until 6krpm which is when turbo finally kicks in and 6-8k rpm is over instantly and defi showing around 1.2 bar maybe slightly more.

Sometimes it wont go over 0.7 bar. Sometimes it will hit 1.1 bar instantly.
Sometimes my CEL light comes on a, but it goes off when i restart the car (says its knock but ive changed knock sensors 3 times).

Its kinda hard to explain really. on a perfect day (after ive reset my ecu). i'll get 1.3 bar every gear and turbo will pull at ~3krpm.

On an average day it wont pull until 6krpm and itll stay at 0.7 bar maybe going upto 1bar.

and when my CEL comes on i think it sets the ecu into ''limp'' mode which keeps it at 0.7 bar i guess?. again the CEL goes off when i reset the car.

Possible Causes
Knock sensor (refitted new ones twice)
Bad grounding causing cel and then onto limp
vaccuum leak causing
turbo faulty


-----

Like i said on a perfect day it runs amazingly and then next day itll just decide it doesnt want to (its not always the CEL, sometimes the CEL wont come on for weeks)

any help appreciated

Ash

gazney101

iTrader: (5)

Any fuel cut?
Has the car been mapped?
Have you made any recent changes to your setup?
All fuses OK?
Does it run if you unplug the maf?
What car is it?

Ash Webster

By fuel cut do you mean like hitting a brick wall? No, it's not like that

It's been mapped about a year ago by Andy Carr

The only recent change was an uprated fuel pump

By fuses ok what do you mean? Should I take them all out 1 by 1 and check? What am I looking for?

I've been told it should be a mafless map but I'm apprehensive about taking the maf off and running it. Shall I try? What will happen if it is/insnt?

98 v4 Jdm sti


Thanks for your reply gaz, and appreciate the time

Ash

The Rig

iTrader: (13)

Could be faulty actuator

mickywrx

iTrader: (29)

Comes on boost at 6k? It's fcuked.

gazney101

iTrader: (5)

No probs, as the rig says, could be faulty actuator or boost control solenoid aswell. A quick test is to remove the pipe connected to the wastegate and see if it will boost more, only do it once and be careful not to let it over shoot what it's been mapped at.1.2bar?
If it's mafless, unplugging the maf should have no effect at all.
I believe it must be fitted with an aftermarket ecu as I don't think classic ecu can be mapped.

As for fuses I would deffo check all of them just in case.

What fuel do you run it on?

gazney101

iTrader: (5)

Either that or he's fitted a gt4294r on a 2litre lol

Ash Webster

I run only on vpower as that's what it was mapped for.
I'll try that test tomorro (weather permitting!). It was road mapped and it usually maxes around 1.3 bar.
As for the maf what about if it's not mafless and I unplug it? Don't want to cause damage so what am I looking for?
Yeh it has an aftermarket ecu but I can't for the life of me remember what it is. How do I find out?

I would normally agree with you if it wasn't for the fact that when it works it comes on at 3.5k so that's pushing me away from t being a duff turbo. It's a vf24 btw (standard on the v4 sti)

Ash

gazney101

iTrader: (5)

If it's not mafless and you unplug it it should cut out or run like a bag of poo, I think It will be mafless though.
Hope it works out the cheapest fix for ya

scoobyricht

iTrader: (4)

sounds like the ecu is picking up knock and pulling timing and going into limp mode. pull back the passenger carpet and remove the ecu cover plate. see what you got.

gazney101

iTrader: (5)

That's what I first thought but new knock sensor and mapped and running on vpower sought of threw me off.

scoobyricht

iTrader: (4)

Maybe not a knock sensor fault but actually picking up knock/det when ur boosting. So going into limpmode. Have u tried the diagnostic connectors under the dash
.. if u have esl in there then that still functions. Count the flashes. Could be another issue causing det not just fuel. Air temp can mess things up especially if mapped when ambient temp is cooler.

mickywrx

iTrader: (29)

Going along with some of what's been said. You need to check what ECU you actually have. Some aftermarket ECU's use the OEM casing so you'll probably have to pull the cover off.

Only ESL retains the OEM error code facility.

Ash Webster

I'll get it opened up and check what ECU it is tomorrow morning as it's currently pouring down and my tools are at the lockup! Thanks for the help so far guys

Ash

Ash Webster

This is my ecu. Any ideas?

Ash

JDM_Stig

iTrader: (3)

you need to unplug the ECU and remove, then take the ecu cover off, take picture, and put it all back together.

Ash Webster

JGlanzaV

iTrader: (3)

Diagnostics will work with the ESL boards

ossett2k2

iTrader: (9)

Are you running a standard intake pipe?

As JGV says you still have oem diagnostics so you can check for CEL codes and reset the ECU using the green and black plugs if you don't have the ESL lead.

Ash Webster

No I have an induction kit on mate.

I'll try the diagnostics and the ecu reset, but I've a sneaky feeling it'll come back the same - knock sensor , and then the cel will still come on intermittently as I've described above I'm tempted to leave it with scoobytek for a week but I'm pretty sure they're sick of trying to figure it out too!! Andy Carr said it might be a grounding issue but I've no idea where to start with that....

ossett2k2

iTrader: (9)

Not induction,,has it got a standard Intake pipe? The pipe that runs to the turbo.
This is a standard one:

ossett2k2

iTrader: (9)

Just to add,when you fit the new knock sensor,did you clean the where it seats on the engine block ?

JDM_Stig

iTrader: (3)

did you also torque it up correctly ?

Ash Webster

I got the new sensor fitted at a scooby garage so i'd hope so!

and yes i have the standard turbo intake pipe

ossett2k2

iTrader: (9)

Which induction kit are you running?
What other mods apart from induction kit?
Standard recirc or VTA dump valve?

Ash Webster

its a ramair filter
full 3" decat turbo back
walbro 255 (which is very loud but i have no soundproofing)
NGK PFR 7B sparks
resonator delete
no other mods as such (that i can think of).

ossett2k2

iTrader: (9)

Ramair foam filter? If so have you taken it off and checked?
I've heard of cases where a piece of the foam coming off and getting stuck in the induction pipe.
When did you last service the car,could be a spark plug starting to break down?
Has it got the standard 2 port BCS? Check all the pipe work for cracks/splitting including intercooler Y-pipe.
Also might be worth giving the BCS a clean,you can activate it by plugging the green&black connectors and spraying a little carb cleaner in there to flush any crap out.

Just a few ideas,hope you get it sorted mate

Ash Webster

Thanks for all the advice.
I'll get checking each possible cause over the course of the week . Should be easier to fix now it's not my everyday as I've got a bike to commute on now (650 cbf)
I've been wanting to get a 3 port and a fpr as well so maybe they will help.
The car had a full service in Jan so it shouldn't be too bad on the basics.

Cheers for the advice

Ash

scoobyricht

iTrader: (4)

never been keen on the foam filter.. is there ant buddys around you that might have the esl cable? if ur ever down south wales then let me know. ive got one and its awesome

ossett2k2

iTrader: (9)

Defiantly agree with scoobyricht,cable is very handy to have,even if you're not mapping it's great to do some data logging