xtreme997

Ok here goes 2001 Boxster S approx 75k miles Cold start runs rough and misfires after about 5-10 sec then misfires for about the next 45 sec or so, clears up and runs great. No faults stored (UGH!) check MAF with PST2, reads approx 55 kg/h (<=problem but don't know why) during this cold start period then goes back to normal readings also checked all the temp readings, ambient temp, intake temp, oil, temp, coolant temp, all is spot on correct. also checked plugs which looked good, and ignition coils have no cracks (plus the car runs good when warm) Replaced MAF sensor and air filter - still not fixed (I know, I know, just throwing parts at it. but need to start somewhere) Checked fuel pressure (check's ok, although It seems to loose pressure over night and the pre charge when you first turn the key doesn't always build pressure, weird I know, but doesn't seem to affect the misfire weather you start it at 20 psi or 50 psi pre charge It won't misfire until it after it gets to the 44 psi running pressure.) Injectors are NOT leaking, fuel pressure must be bleeding back to the tank, Don't think it's pump issue (once warm car won't come off operating pressure even running on hard accel. to red line) also checked for intake vacuum leak with smoke tester - checks great. just to rule it out I replaced the original AOS with new also thought maybe the servo motor in the throttle body was acting up so I cleaned it with no luck then I swapped with another known good part with no change, performed many TB adaptions during the whole process. even checked FRA's, and RKAT's (even though cold start enrichment is precalculated time based operation) and they checked within spec. Any more idea's would be helpful. Thanks