cphelps

I installed a fabspeed exhaust and intake on my GT3. The intake has an oiled air filter. At the track last weekend I received a check engine light. I had the car scanned and the results are random misfires in cylinder 4 and cylinder 5. The car seemed to be lacking some power in the mid-to-upper band. I'm assuming this is related to the exhaust / air intake. Any thoughts on what caused this? Is it a MAF issue? Should I reset the codes and see if it happens again?

I searched and saw some threads related to this in the other 996 sections - but didn't see anything that addressed this specific problem.

996FLT6

Maf seems to be the issue with cel. Ne issues driving home like hesitation and stuttering? Mike Ps- never been a fan of aftermarket intakes other then gruppeM but $$$. Intake from Fabspeed? Which one? The dual cone one or the old open flat panel one? Mike

enthusiast

Oil from filter may contaminate the air flow sensor. You made quite a few changes so this will be a bit harder to isolate.

cphelps

It's the open flat one. It was thrown in with the exhaust I bought. There's no hesitation and the car idles fine. Basically at 4k rpm it feels sluggish. Under 4k it feels fine.

996FLT6

U don't happen to have the stock airbox? I would put that on and see if nething changes. Mike

911SLOW

clean MAF from oil with electric contacts cleaner spray

remove the open airbox and put it in the garden allowing birds to make a nest

check exhaust and connections for leaks

erase faults

go drive

Mr Michael B

+1

cphelps

Thanks, I'll give this a shot tomorrow and report back. I still have the stock airbox so Incan switch that out.

M3EvoBR

switch and keep the stock one. I haven't seen anything better so far.

ltcjmramos

^GruppeM carbon fiber airbox (because 911slow sold it to me, and he wouldn't lie)!!! And it looks so purty!!

FFaust

Conventional wisdom (?) seems to say that too free-flowing an exhaust is damaging to your torque curve. 4,000 rpm is getting pretty close to the fat part or said curve, could this be a problem here?

Never been explained to me why this cause/effect, so I can't justify my comment, but I've heard it enough to start believing it...

cphelps

Just a quick update - I put the stock airbox back on, cleaned the MAF with Electric Contact Cleaner, and reset the codes. The problem is still there - the car is just missing it's power, and the check engine light came on as soon as I went to about 6k rpm. Could the MAF be bad?

996FLT6

U could have a leak from exhaust as well during installation or started thereafter. If an maf is really fouled up no cleaner will fix it. Also drive it a little while maybe computer needs to adjust. Mike

911SLOW

Get an OBD reading and post the fault codes.

in the meantime pm me your details, I will send you a new MAF to try.

cphelps

I tested out the MAF John sent me (Thanks John!) today and it didn't fix the issues. Basically, when I hit 6k+ rpm the check engine light comes on. But, the car isn't running right at normal RPM's either. The codes are random misfires in cylinder 4 and cylinder 5 each time I have them scan and reset. I changed the airbox back to stock prior to having the codes reset and testing the MAF. I think my next move is going back to the stock exhaust and headers - back to ground zero with no engine mods. Any other ideas are greatly appreciated.