I just put my car on the dyno a few hours ago. I have an 06' MT with Nismo CAI, headers and exhaust. After about 6000 rpms the HP falls off dramatically, and there is severe detonation/pinging. Although, my A/F ratio looks pretty good.

Has anyone experienced anything like this? I have heard two hypothesis so far,

1) I got bad gas (insert 3rd grader chuckle here), although I am usually using BP or Shell premium. I'm not buying no-name gas.

2) I need the ECU tuned because of the additonal air flow from the headers.

My problem with the possibility of #2 is that if that is the case Nissan should've made a disclaimer that an ECU tune should be done after the headers are added, but I've heard of no such thing. Plus all my work was done by the dealer and when I went back with my dyno print outs they were the ones that suggested an ECU tune. Well... WTF??? Shouldn't they definitively know one way or the other? It's Nismo parts for crying out loud!

Anyway, I'm going to run this tank of gas down and try another pull in a week or so when I have fresh gas (ha ha). But until then, has anyone seen HP numbers drop off like this? Unfortunately, the shop hasn't run any other Z's with headers so they don't know if this is tyipcal (it seems headers are one of the least common bolt ons, at least around here). Has anyone else added headers and done a dyno, without an ECU tune? If so, can you share your results? I'm curious if I'm the exception to the rule or if this really is an issue common with headers. Thanks.



BTW please forgive the dual postings, I really wasn't sure if this belonged in tuning, or exhaust.

 

Take some timing out, i bet it would help.