help, retune lose power
 

Im a tune noob and only minimal ideas on how it works but here goes

Tune #1
HFC
K&N Intakes
AAM Short tails

baseline 265
tuned to 309

Tune#2
replaced K&N with Takeda CAI (installed 3 weeks ago)
replaced nismo hpipe and midpipe with AAM S-Line Midpipe (installed today)

Time between tune, maybe 3 months
NOTE*** my check engine light came on last week for post cat fuel trim lean bank 1 and bank 2, car was noticably sluggish, and exhaust note didnt sound as good

baseline 275
tuned 286


how is this possible? tuner did not have a direct reasoning to justify these numbers, they were made on same dyno, DynoDynamics

only reasonable explanation was the CAI has some sort of restriction to affect this power loss


Any ideas?

I will see if I can get the graphs and post them up also once Carl is in, it was very strange.

BIG question is same dyno, what where the conditions, how humid was it , weather effects a lot. I had to wait over 2 years to complete my comparisons , because I use the same dyno and go the same time of year so temps are very close.

Maybe you had an O2 sensor on the way out for tune 2, and it finally just died on you?

I would have thought he looked at that before the tune. But EH maybe not.

hmmm interesting....

It's a 2015 though. That wouldn't even have crossed my mind. A failed O2 would decrease that much power?

Tuner suggest possible takeda cold air intakes rubbing against the crash bar or bumper that that is severely decreasing air flow.

That sounds like an excuse to me. I have them and there are over 2 years old. The only part the could "rub" is rubber :/

who did tune #1, dyno used, conditions?

who did tune #2, dyno used, conditions?

plus not sure if that 02 issue would really drop you that much HP. with the mods added you should have gained a little HP based on better exhaust flow and better intake air flow.

Conditions are very similiar. Same dyno same tuner

The only way to be sure is do back to backs on the same day with the different intakes and then the different exhausts if you can. Everyone poo poos the K&N intakes but they have always given the most dyno proven power in my experience. You might be surprised if you throw them back on and you find your missing ponies. I don't know why you would replace K&N's with Takedas.

I doubt I would find 30 hp though. That's unheard of. I already sold them. Heard they only dyno well since you got a big fan blowing cool air during the run but in real life you are taking in all the hot air in the engine bay.

The reasonable explination here is that your CEL is obviously cutting power if your car "felt sluggish" once the CEL was on. Figure out the lean condition and you'll get your power back. Sounds to me like there may be a vaccum leak/post MAF leak/unregistered air. Check the install of the intakes.

As of currently this is the only explanation that we have found that makes sense, the only two changes made to the car since it was last on our dyno was the addition of the AAM Y and mid pipe that we installed that day, and the switch from the K&N intakes to the Takeda intakes that you had done a few week prior. Weather was very similar between both. The car just gets very rich under load now. Of course this can be leaned out, but we would rather find the issue and gain back the power that way than trying to put a band-aid on it.

From everything we see, how the car is reacting, and the power numbers, there is a severe lack of airflow compared to the last time we had it in.

Either the intake itself isnt able to flow, or the filter is just getting no air (My guess) After looking over it, the '15 Nismo bumper puts nearly no air into that area.



A pull was done with the CEL on, and a pull was done with it all cleared and re-set, the difference was very minimal. The car is not running lean what so ever according to the AFRs on the dyno. The car is actually running very rich.