Car feels a little less peppy
 

I have a 2013 FRS AT and it seems a bit less peppy currently. It has 31k miles on it and does get regular oil changes and maintenance. Also there are no codes showing any problems when I do a scan. What could be causing this? Everything is stock and I only use 93 octane gas also.

has it been less peppy for a prolonged period or just in the last day or two? I know sometimes in certain weather conditions my car feels a tad slower as well due to the timing changes. How is the intake filter looking?

I need to check the filter. Its been less peppy for about 4 days now.

There is so much construction going on where I live and where I work. Maybe the filter needs a cleaning.

I'm also in Florida, really peppy in the morning but not so much on the way home. The temperatures around here have been swinging wildly from morning to afternoon. Seems to have a big impact on this car.

Yeah the car was running great with that cooler weather we had for a while.

So, not to hijack this thread, but it's sort of related... I recently read in GRM a recommendation from a well established Subaru tuning house that they suggest walnut media blasting to remove carbon buildup from the FA20 intake valves in WRXs every 30K miles (!). Since common symptoms of carbon buildup are lower power, poor idle quality, etc, I wonder how much truth there is to this, and how applicable this would be for us...?

They say the port injectors help out with carbon buildup normally associated with DI. But it may still be helpful.

Less applicable to us, as we have port injection as well as direct. The main reason for the carbon build up is that the WRX is DI only, so there is no washing for the intake valves with fuel.

Yeah, and because of this, I try to drive somewhat frequently in a manner which uses the port injectors, and use the best quality fuel (high detergents) I can find. However, the 30K mile recommendation still surprised me quite a bit... Would we double that for our cars versus the DIT motors? Triple it? Or maybe only half again as much? Or is it enough bullshit to not worry about it? Dunno...this is my first DI car.

Clean maf sensor?

High heat/humidity really effect these cars.

It is possible I got used to the cooler weather we experienced. I can not remember such a long cold spell in Florida my 40 years living here. Not that is was to cold but in the low 50's in the morning in Fort Lauderdale for about 1 month at least. Now that it started the summer rains and warmed back up it might be the cause of this.

This ^
No cars like hot, humid weather and these are not immune to it. Since they rely on high compression for power they can even be a bit more susceptible to it.

I live in soflo and the difference in temp between morning and afternoon can be substantial. E85 seems to soften the blow somewhat but I can still feel the difference.

Its a lot more and maybe since this is the smallest engine I have ever owned I never experienced such an impact on the other cars I have had.

I am going to check my filter and make sure its still fine. I was asking to make sure no one else has experienced this issue and maybe there was something more specific causing it.

+1 for heat and humidity. I feel the same thing in the summer.

I do as well. Both days.

Unfortunately there could be a dozen different reasons why a car feels off on any given day. Weather is certainly a factor, as many have mentioned, and probably the most easily forgotten one. There's also your air filter, fuel filter, or any other number of consumable things involved in your running process. You could get as many different answers as people you ask. My thoughts went to possibly getting a bad batch of fuel, which is always a possibility even from known brands that are supposed to be higher quality. And there's no remedy for that except to run through the tank and hope the next fill isn't the same or worse.

As long as it's not a gross loss of pep, I wouldn't sweat it or think the car's getting old already at 30k. Heck, @Tcoat is in the six-figure mileage club and (I think?) still even on his original spark plugs.

Yep. Original plugs and still zero indication of a power drop.
I have the TRD drop in filter and clean it about every two months or so. It has been almost plugged solid on occasion and I really hadn't noticed any serious drop in power. Maybe just a slight reduction in throttle response but nothing that worried me enough to check earlier than I had planned.
These cars are so tightly monitored that I would think any fuel filter issues would throw a CEL if it was enough to impact driving but since I have never seen a CEL for any reason on mine I can't be sure.
A mildly bad batch of fuel could certainly be part of it and that issue I did have once. If that was the case though it would run the same all day and not well in the morning and worse in the afternoon.
I know on the very rare occasions we get a really hot and humid day I can notice a slight decrease in "pep" but I have had that with other cars in the past so I was aware of what was going on. My old Talon TSi HATED hot humid weather and had a significant decrease in power whenever it went over 80 outside.

I need to check my K&N filter. I have not cleaned it in a while.

I'm in the camp of having noticed and been surprised by the difference of "pep" between temperatures and humidity. But I'm not sure I'd say there was ever much of a measurable difference in terms of acceleration.

Someone over on the MK6 GTi forums (when I had that car) posted dyno results from the same dynometer between a hot and humid day vs a cool day with almost no humidity. They found that the WHP changed nearly 30 hp. (the motor was said to actually produce up to 230 at the crank compared to the listed 200.) I can attest to how shit the car felt on 90+ degree days. So on cooler days you got the full 230-ish.

So that sort of goes to show, at least in the case of a FI motor that requires lots of air volume, how weather can affect things. But density of air wouldn't be as important on an NA motor, and thus heat wouldn't play as big of a role, right? You put a new intake and filter on the GTI and you get 10 hp. On the FA-20 you get what, like 1 hp?

Density and to a lesser extent humidity affect all engines. Some just show it more than others.


The difference between changes those two car's intakes are the results of equipment efficiently not air density. The GTI intake sucks (or doesn't depending on how you use the word) so changing it has more impact than the Twins one which is simply better to start with.

First, I mostly only noticed a big difference when I was already at speed and needed to pass someone. Second is it is definitely from the weather. This morning was 70 when I left for work and the car was feeling normal again. Just now when I drove home I tested it and as even though its not very humid today I did feel a slight drop. I checked my filter and its still fine. Thanks all!

One way or another, most of us have felt the difference in performance one day or another. Kinda reminded me that it's time to check my air intake filter.

Also, this is another fine example of threads which make me like this forum so much. I expected somebody reply to OP instructing just to slap a turbo on it, or blame the "torque dip". Instead, we got sensible, useful and palpable information re: GTI (despite no evidence was posted).

Thanks for posting!

I felt the same thing in Florida and being my 3rd year in to get a better feel for the car, I noticed it runs much stronger during winter here.

Small displacement woes

OP needs an Italian tune-up.

Get on your favorite "closed track" in Mexico and beat the piss out of it. Wind it out in 4th and 5th, work out all that carbon build up