0.5 boost,cuts out and surges,help pls
 

hi all, first post so may as well make it big, hope someone maybe able to give me an idea as to what the hells going on with this car as ive just about lost the will to live with my scooby, its a 94 wrx import which ive had for a year, its got a api built engine, full decat straight through yoshii exhaust, has a prova ecu/hi flow cone filter and intercooler,as far as i know the rest is standard, was told by the previous owner to use an octane booster as jap cars use higher octane fuel,been dosing every tank with noz and have not had any issues till i let the missus use the car,she filled it up with fuel but instead of putting a third of the bottle of noz in she tipped the whole dam thing in without pre mixing it as ive been doing, next time i went out in the car it was spluttering and running like **** and after a few miles it started to smoke badly real bad thick black smoke, the car would not rev above 3000rpm and would not boost at all, got it home and after some interrogation my other half admitted her slight mistake, anyway drained the tank and filled with fresh fuel thinking this would sort it,no chance,engine light was on so i connected the read wires and got the following faults ,idle control valve ,throttle sensor,boost solenoid ,neutral position sensor,d check mode confirmed these,i have changed all but the neutral pos sensor,i now find the car idles well and doesn't smoke however it still shows a fault with the throttle sensor even tho ive set it according to the Manuel, im now finding the car wont boost beyond 0.5, also there is a dead spot between 2000-3000rpm, if i try to hold the revs at 2500rpm the engine will just surge up and down like it cant breath, would this be anything to do with the neutral pos sensor? ive tried to reset the ecu but find i get a code 43 coming up with the other codes ,does anyone know what a code 43 is? it aint in the Manuel so i am totally lost,any ideas what to check next,the car was running like a rocket before and is now just a shadow of itself,

Anybody out there?

Done a bit of searching about and code 43 doesn't seem to exist?

Recently mine was boosting to .5 and it was very likely it was due to a ecu code putting the car in limp mode, did the reset and boost was one :)

Yours does sound different though because you have a lot of codes, do you only have one code left on there now after replacing the other stuff?

Could have been caused by the whole bottle of OB clogging up the injectors initially, causing the bad running and throwing up those codes.

Did you reset the ECU bfore buying all those sensors?

Regardless, you've spent the money now, and at least it's idling okay and not smoking... just won't go past 0.5bar boost. Therefore, it's prob gone into the 'safety' limp home mode (because of your missus's faux pas), so just reset the ECU and go from there...

Chances are it'll clear the old learnt settings/codes/limp-home mode, etc, and you'll be good to go...

Go do it!..

Thx for replying,I've done the ecu reset but it won't give the ok code,instead I just get four long and three short(43) also throws up the throttle sensor code and neutral pos sensor codes,ime lost with the code 43,I bought the replacents on eBay quite cheap so still costing me less than the garage would charge to diognose the fault,maybe the replacement throttle sensor is iffy, can the throttle itself screwup and cause the ecu to output a trouble code or is it more likely the sensor is shot?

43 IS Accelerator Pedal Switch, if that helps...

Scoobypedia | Trusted knowledge for everything Subaru | Knowledge / Subaru Specific Trouble Code Definitions

Thx,not sure if it's got of those but hey least I ain't seeing things,any idea if the neutral pos sensor can affect the running of the engine?cheers

there is indeed a throttle pedal switch iirc.
imo octain boosters are a waste of money. they are a con. they dont raise the octain by much. your best to run tesco 99 ron and leave it at that.
if you are really struggling i would get hold of a new ecu of ebay. a u8, w6 or z4. they go for less than £40.

Yes, a malfunctioning TPS or NPS will adversely affect the running.... but I can't remember exactly what the symptoms would be. :brickwall

Hopefully JGM or other specialists will post up and give you some insight, etc...

would it be safe to assume that if I still have fault codes present then the ecu will not reset? I have tried to reset a few times without success,also this maybe a silly question so please excuse my lack of ecu knowledge,if I do reset the ecu will this change the map settings? Or is the reset just on the fault

Oops posted too quick,I wasn't sure if reseting the ecu would also reset the map to a standard setup or are they completely different circuit?

No, Subaru's OEM programmed-in map values stay in situ - they're stored in the non-volatile memory of the chip.

What it does is do reset the learnt values of the IAM (Ignition Advance Multiplier) to it's middle positon "8" (out of 0-16) and clear any fault codes. Over a short period of driving, it will then, hopefully, advance the ign. timing as much as possible - but up to the threshold of whatever detonation is happening within the motor. If minimal or no det whatsoever, then you should get the full "16", and maximum power.

Ecu reset
 

Would the fault codes that are still present stop me from resetting the ecu,I've tried a few times to reset but still get a few codes coming up,I'm a bit lost actualy as when I run the car in d check mode I am only getting one fault code flash up(throttle pos sensor) but when I try to reset the ecu it flashes up two more on top of these,(nautral pos sensor/and accell pedal switch)what does this indicate? Ta

Ecu reset
 

Would the fault codes that are still present stop me from resetting the ecu,I've tried a few times to reset but still get a few codes coming up,I'm a bit lost actualy as when I run the car in d check mode I am only getting one fault code flash up(throttle pos sensor) but when I try to reset the ecu it flashes up two more on top of these,(nautral pos sensor/and accell pedal switch)what does this indicate? Ta

It will reset the codes... but if the sensors 'see' that there's something out of spec (whether real or 'phantom'), then the codes can/will show up immediately again, upon turning the ign on again.

Normally if this happens, then odds are that the sensor/s in question DO actually need cleaning/replacing, etc.

But that said, sometimes - annoyingly! - the codes won't necessarily directly relate to that particular sensor/problem... Which isn't particularly helpful when trying to diagnose, etc...

hmm,as I have already changed the throtle pos sens do u think there maybe an issue with throttle itself?I have set the sensor to what the manual says,I did however have a little trouble setting the idle switch which should display o volts when the throttle is closed/ignition on, mine reads 0.25 v with the throttle sensor turned as far as it will go to the closed position, am I doing something wrong?

NEW E.C.U OR BORROW A MATES SEE IF THAT WORKS

Yeh may end up doing that ,gettin proper pissed off with the car at the mo