CAI question, need expert opinions.

[)-shArk>]

Hi all- I just put a BMP CAI w/ 9" KN filter on last month, and it really made a nice difference on accelleration.
One prollem tho- Once in awhile when I punch it hard I get a backfire through the intake. It does not do this w/ the stock airbox, only w/ the CAI. My car is in top shape and nothing in the engine is worn, was thinking mebbee with the CAI I am running too lean? Too much air and the injectors can't keep up?

Any thoughts would be helpful.

[1995red318i]

i have never heard of that.
have you tried running a search? maybe you can find something about it there?

[)-shArk>]

Originally posted by 1995red318i
i have never heard of that.
have you tried running a search? maybe you can find something about it there?

Ya, I usually try that first. Nothing popped up.
I figure with the many BMW experts hanging at this site, someone has had to have seen this problem b4.

[v.b.]

back fire?
you mean the intake split fire?? :

[TBM311]

im guessing he means back fire from out of the exhaust.

[bsut]

A backfire happens when you suddenly close the throttle and there's not enough air to burn the fuel that's already in the cylinders. When that unburned fuel is expelled into the hot exhaust manifold, it ignites on contact. The burning happens in the exhaust manifold, not in the cylinder.

That's the traditional meaning of the term "backfire", and I've only experienced it on carbureted cars, never one with fuel injection. Note it only happens when you suddenly lift off the gas pedal, not when you have the throttle open for acceleration.

If your engine is running too lean, you'll hear a rattling or pinging or knocking sound under wide open throttle.

Could you provide a bit more description of your symptoms?

[ekdemos]

What kind of BMW do you have? is there a cold air supply. send me a picture and I will see what I can do. sounds like a messed up sensor. the reason you do not notice a difference is because you are probably sucking hot air! you will notice the difference if you have ram air.

[332 RustBucket]

I used to get backfires all the time with my tri-flow exhaust. It sounded awesome!!! But too loud My guess is that I could just hear it more because of the loud Tri-Flow. Never heard it b/c of an intake?? I also have never heard of it when you punch it? Can you tell us a little more? Maybe if it happens more cold, after long drives, only spirited driving, etc.