2014 FRS Power Loss
 

First post on the forum!

Back in April this year, a friend and I installed Tomei UEL headers on my FRS.

Didn't run into any issues with CEL, the downwind spacer seemed to work just fine. Everything was great for about a month until I went on a road trip for a couple of hours.

Highway pulls were amazing, especially coming off of toll booths, but towards the end of my 2 hour drive it seemed like something wasn't quite right. Once I got slowed down and off of the highway, RPM was sluggish to rise and fall compared to normal. It was enough to make driving annoying. Still no CEL and my local dealership didn't want to bother looking into it.

The car has been reliable since then, but I'm still dealing with power loss and I don't know where to turn. I ran STP fuel system cleaner that helped some, but the throttle is still sluggish and the car won't chirp the tires if I take off too quickly (and I'm getting to the point where I need new tires.)

I have not had the car tuned yet, which some people that I've talked to said is necessary, but I've also seen threads where people have driven thousands of miles on catless headers without tuning and without issue.

did you replace the gaskets when you installed the new headers?

Yes, brand new Grimmspeed gaskets

Do you have an OFT or some sort of tune?

edit: no you don't, and I think this is why. Just because others have gotten away without tuning doesn't mean you will

- Intake leak?
- Clogged/dirty air filter?
- Oil change needed?
- Clutch resisting engagement?
- Spark plugs corroding?

Loss of power could be many things, I'm afraid. Turn off the AC and try to accel, make sure AC isn't bogging down the engine any more than normal latency. Fuel pump could be slacking too. In neutral, does the engine sound/feel like it's losing power? Could be something in the drive train causing the loss if not. Have you been under the hood to make sure the headers haven't come unbolted, could be exhaust leak?

Non tuned engine running catless header. I would start (and probably end) your search there.

Absent an exhaust leak or crack in the header, a tune will probably be needed to run the header properly

I think an open flash tablet is in this anon's future

That's understandable. I had just seen a lot of posts where the headers worked fine, so I was worried something else was up.

I took the intake apart and made sure it was put back together properly. Brand new filter as well. I don't have a way to check on the spark plugs, but I'm up on maintenance. There might be an exhaust leak. I hear a faint air rushing sound from the engine bay, but I also read that headers will make that noise normally under power because they are thinner metal and there's no shielding unlike the stock design.

It seems that is necessary.

I've looked at the OFT, but I'm also considering a dyno tune. I feel like maybe a professional tuner might also catch if there *is* something wrong.

Does anyone have experience using an OFT tune?

Get an OBD2 port reader and the Torque Pro app for your smart phone. Then we can stop wildly guessing and you can tell us some info we need to figure this out.

we need-

-LTFT at idle and 2500 RPM and IAT at the time
-log of timing advance, AFR and oil temp


Butt dynoes are notoriously unreliable so if you have actual performance metrics from before and after that's be a lot more handy than just "feeling" down on power. Do you have before and after 0-60's, 1/4's, anything else? Actual dyno numbers?

I just ordered an OBD2 scanner, so I'll post the numbers Monday if I can get them.

No metrics from before unfortunately.

I'm not sure what I'm doing, but I got a short drive logged.

I added it to my Google Drive https://drive.google.com/file/d/0B43...ew?usp=sharing

Bumping with a cleaned up spreadsheet.

https://drive.google.com/file/d/0B43...ew?usp=sharing

It looks like the LTFT is consistently negative while driving.

I also noticed some corrosion on my o2 spacer, so I believe there's an exhaust leak there.