Backfire causes?
Discussion
Just took my car out for a Christmas Day blast. Gave it a good old 'enthusiastic' run for about 30mins. After giving a blast slowed down to go through the village on the way back to my house (around 2-2.5k revs) and I started getting a couple of very very loud bands out of the exhaust. Much much louder than normal (I have decat and loud cans) it also did it a couple of times whilst I had my foot on the accelerator which it never does. There doesn't seem to be any loss in performance and is ticking over fine as normal. with the bang every now and again about 3 or 4x louder than usual!
Any ideas anyone?
Any ideas anyone?
Cooper Green said:
Sounds like it could be a valve sticking open during either the exhaust or inlet cycle, had a similar problem with a Calibra Turbo 4x4 some years ago. Burnt out 3 sodium filled valves in the process. Sorry for the doom and gloom at xmas. 
hhmmm... slightly concerning, particularly as it sounds like the logical answer... Would this be regular or could the bang occur randomly. at the moment it is very random and spread out. this would make sense though as it is F!#%ing loud! much louder than the normal pop/bang that it will easily make you jump. Im guessing that if the explosion in the cylinder was occurring through the exhaust due to the exit valve being stuck open that would be the cause of the bang. What makes it confusing is that it doesn't seem to stutter the engine. would this be the case if it was the valve? or would it loose power/skip a beat due to loosing the full combustion in the chamber?
I very occasionally get the same altough I don't think when on throttle. These are a once in a blue moon explosion and not the normal pops and only when the exhaust is nice and hot. Mines also decatted with loud cans. It does not worry me as its obviously just an extra loud pop when a bit of extra fuel has made it into the hot exhaust and the car runs perfectly otherwise. It would worry me if it was on throttle. I would get the throttle bodies balanced if I was you.
Ok, so started it again this morning, it's definately running lumpy.
Did a quick test with the injectors,
The front three injectors all made the engine lumpier, however the rear 3 injectors seemed to make little or no difference to the running of the engine.
So logic would dictate that it's an electrical issue...?
Anybody have any further ideas here??
Did a quick test with the injectors,
The front three injectors all made the engine lumpier, however the rear 3 injectors seemed to make little or no difference to the running of the engine.
So logic would dictate that it's an electrical issue...?
Anybody have any further ideas here??
Yes, started it again yesterday and 4, 5 and 6 are not fully running (pulled the injectors one tick over removing injector on 1, 2 and 3 made it run very rough, on 4, 5 and six pulling each injector made little/no difference meaning cylinders 3, 5 and 6 aren't doing much. At least that displayed it to something like lambda 2 or the wiring loom for 4,5 and 6. Something that effects just the back 3 is not functioning correctly - recovery truck to take it to the garage is on its way now so will update later today on what the issue is.
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