wrx fifer

iTrader: (34)

ok this is for a guy i know as we are running out of ideas??
car is a 51 plate bug wrx with no modifications

car was running fine,then he ran out out of fuel last week, got a jerry can and topped it up, it threw a cel of lamda afterwards and was not boosting right, like holding back especially 4-5k rpm wont go past like a fuel cut issue??
since then he has changed fuel pump, new lamda, tested 2 working mafs, replaced fuel filter and also ran 2 lots of fuel incase bad fuel, also ran some injector cleaner, also removed vta valve and back to recirc, checked boost solinoid, now he pulled the pipe with restrictor pill and replaced with normal hose and no pill replacement, so thats an issue till he gets another but was doing this before that got removed, i was in car tonight to see what it was like and very juddery and when trying to give it beans and holds back and judders drastically as i say 4-5k rpm like some kind of fuel cut and when this happens a loud ticking,banging from somewhere in engine bay, cant pin point it as your in car but does not sound clever, it's not a knocking and it sounds too loud for injectors, not piston slap either, it has us totally stumped and i realise not something easily diagnosed with out been there so to speak, cel was cleared and reset after new lamda fitted and has not come back on!!

any and all help appreciated

plugs
cat
pill

cant think of anything else really

scoobymark97

air flow mass sensor try a donor one befor replacing with a new one sound like the symptoms of a air flow mass sensor .

TonyBurns

iTrader: (3)

Neutral Position Switch, air to fuel ratio sensor

Tony

scoobymark97

but not the knoicking noise i dont know what this could be but the holding back on power sounds like air flow mass sensor

wrx fifer

iTrader: (34)

a working maff has been tested with no diffrence, and would the fuel starvation cause cause a sensor to go with no cel?

matth76

Running out of fuel is never good as some of the debris at bottom of fuel tank may get into injectors. Most shouldn't though as the filter should stop it but some smaller particles may still get through - not worth the risk. I had it happen to an older car and turned out one of the injectors was very partially blocked which they put down to fuel debris following me nearly running out of fuel - never again. Cleaned it out and it was find after that. Don't buy halfords injector cleaner though as that wont do the job. Not sure though if a partially blocked injector would cause knocking noise. Sounds like it may have had a knock on effect though with something else .. no pun intended

wrx fifer

iTrader: (34)

yeah the knocking is not like a bottom end knock if thats what yer thinking, it will only make the noise when it judders and holds back, at no other time will it do it, hence the very hard diagnosis, and the replacing one thing at a time until you fix it game is not good and with no cel being thrown up?
personally i have not heard it before, leaving me stumped

Pink_Floyd

Could the knock be dodgy engine mounts giving off that sound as the motor judders?

wrx fifer

iTrader: (34)

na deff not engine mounts, if you heard it