Before I start, I would like to say I have read multiple threads and posts about having adding a K&N Sri and not tuning... I am well aware of the risks and I just got it for the sound and not the gains...

Secondly I drive a 2009 Cobalt SS... The previous owner placed a custom trifecta tune on it and that is the only performance mod that I know of.

So long story short, I got an obd II reader and have been using it on my car for a few weeks and have been getting consistent readings.. Then I decided to get a K&N Sri... After the install and computer reset (disconnect the battery overnight and pumped the brakes) I tested the intake.... It sounds and looks great but I can feel a loss in power especially in between shifts... When I turned on the OBD II reader I noticed that I have lost about 50hp and 50 torque... My boost still gets up to 22psi and the car runs good... Just the loss of power and more turbo lag at times... Fuel trims are slightly off as expected (about +7 or +8 long term)... Does anyone have an explanation on why I lost so much power?? I don't think the intake is loose but I guess I will double check tomorrow when I get a chance...

Thanx

 

I don't know how aggressive the current tune is but with the trims off that much it can cause knock and that can be the loss of power you're seeing. You need a retune

 

Idk I haven't heard any knocking...

 

The computer will see the knock and compensate by pulling timing resulting in the power loss

 

And I'm guessing it was a pretty aggressive tune... 353hp and 411torque... I'm assuming the previous owner also got the GM stage 1 along with Trifecta...

 

How are you determining the 50hp and torque loss?

 

I dont think you loss 50 hp and 50 trq lol. go dyno the car before and after adding the intake and come back with the results. No reader is going to actually give you the real hp and trq numbers.

Also if the car was tuned, the whole "dont need to tune with the K&N intake to function" thing is out the window. Its only a well known thing with stock PCM settings. Theoretically it should be fine with a tuned car but who knows what the tuners changed or the aggressiveness of the tune. There is not alot of people reporting running a K&N intake on a tuned car that wasnt actually tuned for the intake..

 

Also I gonna stop you here as well. There is no way in hell you have 353 hp and 411 torque with a Trifecta tune @ 22 psi. Not even if you were running e85 or some mixture of it. Im guess these #s came from your scanner as well?

 

The car feel slower and according to the readings on the scanner... I've done wot multiple times and my numbers are way down from before the sri

 

I actually did go to a dyno a few years ago, obviously before the Sri... I have not gone after though

 

Those number are at the engine, I just posted the numbers at the wheels that I got from a dyno a few years ago

 

Feels slower means nothing. Get 60-100 times 3rd gear pull. My cars feels slower to me now compared to when I bought it.
Still unsure of where these magical numbers are coming from post CAI install, if it's a scan tool ignore them they will be way way off. Also you need to re-read your dyno numbers, they don't match what you're saying.

 

I see the dyno. The only thing id tell people is it made 315 whp and 350+ trq. I wouldnt go by the dyno's back calculation to determine power at the engine. Its different for every car. No idea what correction factor they are making up. If your cars tuned, and you put the intake on. I think you should get it retuned. I still dont think its possible for you to lose power from adding the intake. Unless there is a leak and the MAF is not taking the right reading.

 

Ill see if I can add my 2 cents as well.

U didn't loose 50hp and 50tq, u don't go by the bbd2 reading, those aren't exactly accurate. And you certainly don't go by butt dyno to measure how much power u think it had. 50hp and tq loss would be a huge loss and it would be more than a I think I lost this much, ud know for sure.
don't try hearing weather ur car is seeing knock, cause u wont hear it most of the time, ull only hear it if its bad. use that scanner u have and monitor knock retard, if u see any, then ur car is pulling timing to stop knock.
If you want to try to fix up those trims a little, rotate ur filter, I believe the rule is, put the metal strip at the 11 oclock position for the best result, should bring that +7 down a little, but wont fix it.
And if you value ur car, get rid of that trifecta tune asap and get hptuners, and ask km043 to give u a proper tune. u wont regret it.

u said u get more turbo lag at time, at what times?

oh and this 50hp less ur reading, are u basing that on ur estimation of the engine hp based on what u got on the dyno, then based on that ur 50hp less on ur obd2 reading is whats worrying u? or did u check ur obd2 before and after the intake and after the intake ur obd2 is reading 50hp less than before?

 

For the 50hp and torque loss I was going by the obd2 readings before and after the intake... Honestly it doesn't feel like a 50 change but I do feel the difference... I guess I should have done timed runs..

The turbo lag occurs randomly... Either between 1-2 or 2-3... But only at about 3/4 throttle...

Is it bad to stack a tune ontop of my current one? And how much do they run cuz I don't wanna spend a **** ton of money

 

well don't trust the butt dyno, it lies. And the readings, and idk how the computer calculates hp, but don't trust that either, not accurate.

When u get a new tune the old one is erased. for hp tune ud need to find someone with hptuners software. or get it urself, that's 500, the tunes usually are 250-350 depending on who does it. but in order to get a new tune, ud need to get ur stock file back on the car first, which ud need to get the trifecta cable and the original tune file from that car, if last owner has it. either way try to get that file, just in case one day u want to get a new tune. if u don't, u cant retune cause trifecta tunes are locked, so u cant erase them or do anything with them.

Are you sure u didn't do a run with the tune turned on the first time and now ur forgetting to turn it on? is it a select a tune? that would only be activated with traction control in competitive mode. try doing that see if u don't feel a difference, if ur not already

 

I'll add to the Trifecta lock out bit. If you are truely locked out of Trifecta and cant get the stock tune, you probably can get a spare PCM with a stock tune on it and relearn that PCM to your car. I forget what the relearn steps are but its something simple. I think ZZP sold stock PCMs for LNF cars.


They use HPtuners. It wont be as great as going to a tuner but at least your PCM isnt locked lol.

http://zzperformance.com/ecotec/elec...rbo-pcm-1.html

 

I didn't see anyone mention it. On the k&n filter, do you have the metal pleat on the top? About the 11:00 position. I never experienced it, but supposedly our cars don't run right if you install the filter right side up.

 

yes 11 oclock position