996S - Misfire problem
 

Got a 2001 996S, one of the early ones with the genuine SPS motor, Ti rods, 50mm exhaust, cams etc.

Since fitting after market Arrow end cans I have developed a misfire, or in older terms a "flat spot" around 4.5 - 5k. Have tried original chip, Arrow chip and a JHP chip all to no avail.

Took bike down to Hacketts for a service late last year and asked them to put it on dyno and get it running right.

Wyhen I got bike back, dyno curve looked lovely 128bhp @ 8500, but bloody flat spot is still there.

I decided to give it a while and see if it came right - numpty! It was never going to was it?

Anyway, realise most of you spend very little time at such low rpm, however when tootling along in traffic I often find myself in just this rev band and on going for a quick overtake, bike simply bogs down, farts and splutters for a while before finally pulling itself out of the flat spot - unless of course I have already lost patience and kicked down a couple.

I believe the bike has twin injectors, and Nelly at Cornerspeed has suggested disconnecting one and fitting and FIM chip. Reasoning sounds ok, but reluctant to spend all that dosh and find it's still there.

On the other hand if I could ever get hold of Johnny Hackett I could ask him to take a look at it, but the's a fair way off and to be honest I feel a bit embarassed going back after all this time.

Anybody else got experience of this, and if so how did you "cure" it? Power is awesome in all other respects. Suggestions?

:borg:

Try a power commander. 998s have the same problem in the same place, I understand what you mean about overtaking. I fitted a PC to mine with Akrapovic slip ons and had dynohet set it up. Result 136 and "very reduced " flat spot. it is still not completely gone, but 1000x better and livable. Can send a dyno chart if you wish