Backfiring/Popping From Inlet/Air Filter Bug WRX
12 February 2013, 02:24 PM
#1
Backfiring/Popping From Inlet/Air Filter Bug WRX
Right so I've just changed an engine in a 04 plate WRX and its popping on boost under load from the air filter. I changed the belt on the new engine, my first on a newage but have done plenty on classics. Engine ran sweet first time, allowed it to warm then gave it a few revs and it made a couple popping noises out of the air filter on the over run?
Thought this was strange so went to switch off but before I could get chance I heard what I now know was the belt slipping and it dropped down to 2 cylinders. I switched off immediately and took the covers off to look at the belt, both left hand pulleys had slipped 4 teeth and no indication as to why whatsoever? My first thought was that's it engines f**ked! Decided to re-time and give it a go just in case 4 teeth wasn't enough to kill the engine, car fired first time and idled perfectly, no noises, no misfire nothing. Let it warm up and gave it some revs, still no misfire but popping noise is back but only very occasionally. Decided to road test it and popping occurs soon as car comes on boost, acceleration is very hesitant like a boost problem or misfire. Really don't know what to do now, my first thought is its bent some valves but surely it wouldn't run on the affected cylinder at all? Could it possibly be boost related? Car has boost controller and various other mods, is it possible I have plumbed a boost pipe in wrong? Also worth noting the front lambda sensor is throwing a fault, replacement coming tomorrow. Any input appreciated guys and apologies for the essay!
Thought this was strange so went to switch off but before I could get chance I heard what I now know was the belt slipping and it dropped down to 2 cylinders. I switched off immediately and took the covers off to look at the belt, both left hand pulleys had slipped 4 teeth and no indication as to why whatsoever? My first thought was that's it engines f**ked! Decided to re-time and give it a go just in case 4 teeth wasn't enough to kill the engine, car fired first time and idled perfectly, no noises, no misfire nothing. Let it warm up and gave it some revs, still no misfire but popping noise is back but only very occasionally. Decided to road test it and popping occurs soon as car comes on boost, acceleration is very hesitant like a boost problem or misfire. Really don't know what to do now, my first thought is its bent some valves but surely it wouldn't run on the affected cylinder at all? Could it possibly be boost related? Car has boost controller and various other mods, is it possible I have plumbed a boost pipe in wrong? Also worth noting the front lambda sensor is throwing a fault, replacement coming tomorrow. Any input appreciated guys and apologies for the essay!
Last edited by wotagr8bigchief; 12 February 2013 at 08:18 PM.
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