Hi I have 350z 2004 with tt greddy 18g stock internals, haltech, my problem is late boost. Boost (7psi) appear after 4500 – 5000 rpm. I tried speed up ignition timings but then car starts interrupt. Like spark would be blow out. AFRs are ok on the level of 10-11? What it can be?

 

11 as in low 11's? i would say 10's for afr is far to rich my car has rich misfires that low i would say no less then 11.3:1, personally i have 11.5-11.8 with alot more power. start there and check spark plugs but off the very minimal information that you have given we will only be able to see one problem right now. anything further will require alot more info.

 

oki what data you need?, later I can attached screen from my fuel map.
sparks i changed 2 weeks ago on LFR6AIX-11

 

Sounds like possible boost leak. Have you thoroughly checked your piping and couplers?

 

^+1 seems like you might have a leak somewhere in exhaust or charge piping.

 

I will check ones again exhaust and piping but after 4500 rpm boost is very stable on level 7 psi and if I would have leak my AFRs would be untouched?

 

your AFR's wouldnt be "untouched" but they wouldnt really change too much. I may be wrong but if you add too much timing doesnt it become counter productive to spool up? It does sound like you have a boost leak some place though.

 

maybe this video will help


and maps:
http://s1073.photobucket.com/albums/...t=20b624cd.jpg
http://s1073.photobucket.com/albums/...t=51141415.jpg

 

check for boost leaks and have the car professionally tuned at a reputable shop

 

Sounds like you're hitting boost cut or some other failsafe like knock retard... stay out of boost until you get things figured out.

 

they will be very off depending on where the leak is and how bad. the leak in my 3 bolt gasket under boost causes that sensor to jump 9 points (actual afr around 11.5 but shows 10.6)

 

def hitting something not sure its knock retard though i know im running alot lower compression but im running 8-9 degrees more spark with no issues.

 

Something that I'm shocked nobody has mentioned. It depends what gear you are in as to how fast boost comes on. In 1st or 2nd gear you won't build enough load to get boost fast yet in 6th you will probably have full boost around 2200 rpms.

Something else is going on if it's doing weird stuff like that with the rpms. I can't tell if that's the driver letting off and pumping the gas or if it's misfiring that bad. Too much fuel is just as bad as too little fuel when it comes to misfires.