hello i have a 93 wrx import. i got my MOT due and booked up next week so to pass through emmissions i thought i would change the oil and coolent as i hadnt done so for around 5 6 months. usually i had been using castrol 0-50w oil and the car runs fine on it no probs. i found somebody on ebay selling oil filter, fuel filter and millers 10-60w oil so i thought i would try that instead. since changing the oil the car has run REALLY bad. it idles low and struggles. when you try to accelerate it will not really move and sounds like its miss firing then suddenly kick in and boost like a rocket. i didnt think that you could make such a huge difference from just changing the oil over. i havent knocked any other pipes and the car was going fine on the old oil. it just now runs really bad. can anyone help? i dont want to tip all the oil out unless its defo that causing the problem. ive checked all pipes for intercooler and air intake and anything i can think of. but i have only changed the oil thats it.

 

it cant just be oil, unless youve mahoosively overfilled it!
must be a connection missing somewhere

good luck!

 

i didnt think oil could do that much but it really is all i have done. oil, oil filter (which was same as before just new one) and coolent. all at the right levels and cant see anything wrong.

 

Does it warm up correctly when running? I mean hot air coming out of the vents and mid temp gauge. Just thinking air lock or possible coolant sensor issue, I do believe this can cause a car to go into limp mode.

 

yes it warms up im getting hot air out cos it was cold last night and i had it on, ok its basically anything over 2-3rpm the car is ok but anythng under its struggling. like idle will run ok for around 15 seconds then drop and go back up again. if i hold the revs at around 1.5rpm then you can here its really struggling and sounds a bit like its miss firing.
to change the coolent i just pulled lower pipe from radiator and drained for 5 minutes then refilled till top. ran car for couple of mins so it could circulate then toppped up slightly. then went for a drive for 30 minutes to make sure everything was ok. checked for leeks and then checked level again in the morning. seemed fine.

 

temp gauge has never gone over mid level, was actually slightly lower then normal but i mean only like half a centimetre. that was with running out side my house waiting for fans to kick in and checking for leaks

 

sounds like it has detected knock and retarded the ignition

 

dont know much about that can you please explain

 

will that show up if i reset my ecu?

 

ok i think ive fixed the problem.

i went on holiday for 2 weeks, got back last wednesday. had dodge battery in car and new one in boot. fitted new battery when i got back and got car running. car seemed ok ish, bit of smoke cos oil needed changing but ecu must have been reset due to dead battery for so long. when i changed oil and coolent sensors reading new temps and obviously doesnt really understand what to do.

just taken car out and reset ecu. on the way to long empty road running like crap still, at low revs anyway. i reset the ecu using the plugs, then hey prestow i pulled away when i was done and seemed ok went for a drive for 20 mins and yeah, not once did it struggle or idle low or do any of the other stuff its done last few days. maybe everytime you get a dead battery for a long time you are spose to reset the ecu manuelly. me changing oil and coolent threw it over the top and it didnt understand readings. i dont know but for last few days its been runing bad and reseting the ecu seems to of helped.