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yeah as title say's i have n ej20t (96 wrx) in 86 rxturbo and every now and then when i try to excelerate after letting the clutch out sometimes the engine makes a pop sound that sounds like its coming from the manifold well you can here it out the air filter ??

usually if the engine decelerates then excelerates in quick succession and more so when its cold some times has trouble starting when if very cold and seems to die when you try to excelerate it can have a huge lag before it does anything thats usually when it pops

does anyone know what this could be

well,for a start the backfire through the filter is due to fuel being ignited before the intake valve has a chance to close completely,i would start with basic,s and check the timing belts first..make sure all is well there....check all vacuum hoses, makes sure intake is tight....etc...but it sounds like it could be ecu related....any codes? how long since last service how many k,s are on this engine..all this info will help us help you....cheers

excelent thanks the engine has 80,000 on it.

sometimes the ecu light comes on but i've tryed to check it and when i do it just flashes on and off but with no decernable code. unless i'm checking it wrong or something.

i'll check all the hoses best i can tomorrow and see if theres something there but it only really happens when its cold once its warmed up properly it seems to be fine i think.

i'll check the timing belt tomorrow also

also with what i've described could it be causing any real damage

I've checked the computer codes on it and there are none. The light just continually flashes. I've been meaning to swap the computer from my car with it to try and fix my engine troubles, will have to try it and see if anything happens.

if you cant find the problem with a change of ecu..and no codes to go by..i would test any sensors under the hood which could be exposed to tempurature changes....electronic units and sensors have a habit of giving themselves away as faulty when you change there tempurature...this is one sure sign of a failing unit...you could test there resistance or back probe for voltage readings..as per the factory spec,s..when cold..and then do the same test on each componant when hot( once the car is up to road temp)..apart from the obvious coolant and temp sensor,s they should test the same hot or cold..if one does not..see if you can swap it over on a mates car the same model and you just might find the problem...goodluck..

ok thanks mate i'll give it a go