Hi guys & gals. Im new here although being a Porsche guy for a decade.
Currently running 996tt -01 which Ive been building/modificating for a year already.
Im getting o2 sensor code p1118, replaced with oem Bosch ones, but still. I noticed when accelerating with part throttle 1000-1200rpm the afr jumps to 20 and the engine hesitates obviously. Harder acceleration no problems. Replaced also the diverter valves. Im running mafless Cobb tune, appeared already before though. Searched for vacuum leaks but so far nothing. Maybe I should lower the engine to reach the whole vacuum system? Any input on this appreciated!
Thanks. -JP

 

Apparently the p1118 is for post cat o2, so it's out of question. The hesitation and running rich at 1000-1200rpm is still the question mark though..

 

20:1 is lean not rich, extremely lean. Since you've got a Cobb have you been trying to pull fuel to correct a "rich condition"? If so stop lol! How exactly did you search for,leaks, boost leak test or just visual? If simply visual do a boost leak test...

 

Oh yes lean indeed.. I checked with butane gas for leaks. Have to run the pressure test.
Thanks for correcting.

 

JP,

I've been chasing a similar problem on my 01'TT for 6 months. I still have not found the problem. I've checked / replaced just about every sensor,solenoid, check valve, O2's, MAF etc...I've done several boost leak & vacuum tests. No leaks. The car runs terrible other than at full throttle. Full throttle is much better but still is not right.

Interestingly, I also have a Cobb tune + Cobb injectors, billet turbos, IPD plenum, 997 TT throttle body, intercoolers, new coils, new MAF. I also tried Cobb's mafless but I still had the same issues.

Interestingly, I also have an 01' TT. I wonder if this is only an issue with 01' TT's ? I think(different part #) the 01's have different vario cam actuators/solenoids and programming than 02' to 05'. I wonder if the 01' TT require different mapping?

Karl

 

Check the non pressurized side of the intake after the maf u might be letting in unmetered air that is not being seen by the maf

 

He's running MAFless, unmetered air was my first thought too. Sounds like a tuning issue though?

 

Ah yes thx i missed that