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MG MGF Technical - IS my car now sorted??

Long story.

I have had problems for well over a year with occasional loss of acceleration, especially on full open throttle.

I have changed nearly every sensor I can (coolant, Crank, camshaft,etc) changed cat, exhaust, plugs, leads, various filters, etc etc.

No errors ever show up and the car has been running rich (sooty black plugs, black exhaust pipes, smell of fuel etc).

Last week after fitting a TB, and still having all the usual performance probs, I decided to modify my enlosed box for my K+N. This originally had a small diameter (2 inch?) pipe going to side vent from enclosure.

It often felt as I opened throttle up as if something was holding the car back, it made lots of noise, but never went anywehere. Also pipe showed signs of collapsing inwards, as if it were due to vacuum pressure

Anyway, I added a 5 inch alumnium pipe taken from below the car into the K+N enclosure, so it now has lots of air. The difference has been nothing short of startling!!

I presume my car has been getting starved of air when throttle is opened. This may explain why faults never showed up and emissins were not out at idle etc, as enough air would get in on idling.

I presume this would also add to the overfuelling issues and reduced MPG on long runs. I also have not noticed any unburned fuel when slowing down as I usually do.

I only hope, if this has been the reason all along, I will not lose all the gurgling/popping in the exhaust haha.

Any comments would be most welcomed. For the moment it is just making me smile so much again :)
I Brown

interesting reading!!
Was your K&N encloser home made ?
Did you use the original k&n pipe to send down to the passenger side vent?
I have done the same mod with the air scoops fitted off ebay.
You can hear the "suction" from the pipe fed side vent so the system is deffo drawing cold air ,but i too also wondered if my feed pipe about 2 " is big enough.
My f also has the best performance from cold (when you don,t thrash it !)
The difference from the standard k&n set up is vertually the same unless the engine is cold.
I don,t get any flat spots but often wonder if i should put it back as it was .
Also saw a web site somewhere of a enclosed k&n with the pipeing to the intake duct and under the car as well like the original k&n. Must of been some guy on here.
m e johnson

A 2" diameter flexi pipe is a bit lightweight as the sole supply for the engine, partly due to the snaking path (bad fluid dynamics) and then there's the corrugated inner surface... even worse fluid dynamics 8-( It's a bit of a squeeze, but there is room to get 6" air-conditioning type duct down the corner of the engine bay, and the end rests very securely on the corner of the subframe. Still not a smooth air path, and not great to look at, but it does the job very well just by being bigger than it needs to be, and the only fault Gavin from Techspeed could find with it was that I might find leaves and random debris collecting in the filter enclosure, but nothing in 15,000 miles...

Not surprised you're smiling, you've just returned the power output of your engine to a curve, not a plateau 8-)
Mike Hankin

Yes m e johnson, it was home made, and yes it was the original K+N pipe I used.

As I said, the difference is quite dramatic. I dont know how much of it is the normal engine and how much is the new 52mm TB (not much I gather). I only cringe when I think how much I ahve spent on trying to fix it (including al the tools and diagnostic software etc I now have), when it was my fault in the first place for isntalling the enclosure!!!

Still at least I can now throw my hand at lots more DIY tasks in the F.
I Brown

Two of us over here have installled K&N Filters. Not enclosed but shielded from the engine area by an aluminium shield (purpose built. The filter is fed by a 100mm pipe to the side vent with air scoops. The resonator box was "ripped out" (quite a job)to provide a clear route for the air intake. Results remarkable.

David Richards

This thread was discussed between 27/02/2007 and 28/02/2007

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