Hi,
Recently I've noticed that my s2000 have a Noticeable loss of power, it doesn't accelerates like it used to be.
When I accelerate at 2nd gear (full throttle) the rpm slowly climbs to 9000rpm, simply not like before, It feels like something is holding the car from accelerating
The car was recently serviced, all oil and fluids were changed, throttle body + ICV cleaning , asked the mechanic to check the spark plugs he said everything looks fine.
Could a bad alternator cause such things as loss of power? the clutch doesn't seem to be slipping, but I'll take the car to expert to check the car out. any inputs about the issue I'm having will be appreciated.

The car is bone stock, 2005 model with f20c engine (Where I live AP2's came with F20c only).

Thanks

 

What else has changed? Is it silly hot now?

 

Is it hot and humid where you live? If so, wait for cooler less humid weather to re-evaluate your car's power.

 

It could be a fuel filter... when was it last changed? Is it only happening in 2nd gear?

 

It's around 105F oustside with around 70% humidity.
I took the weather into consideration, but what i don't understand is why is the car sometimes runs perfect and sometimes feels really like something is holding it from accelerating.
all the fluids and oil were replaced recently and thats about it + engine flushing done at the dealer, also I checked the air intake filter it looked a little dirty, will change it and update you guys.

 

Yes it's hot, but why will the car run good sometimes and the opposite sometimes?

 

I'm not sure about this really, but the dealer said they cleaned the injectors as well if that helps and nothing changed.
No, not only in second gear, all gears from what I noticed (but I mostly go full throtlle in 2nd gear thats why i mentioned it in the first place).

 

Heat soak, AC, OAT, humidity. altitude changes, road temps (time of day) can all affect horsepower. Relax and wait for a cool day!

 

Sucks man, I've been there. I agree with the rest of the guys. It could be a heat soak problem, but if you had this car for awhile you know what heat soak feels like.
In my case I felt like I was missing about 20-40% of power, so I knew that it wasn't just heat soak. but some times it felt peppy-ish, so I spent a lot of my time wondering if I was crazy. I knew deep down that something wasn't right though.
I noticed my power loss mostly when scooting around town and shifting at lower rpm's. it would be extreme when I'd be on a long highway drive, then pull off the exit ramp to get gas or something.
My problem, oddly enough, ended up being evap related, as I was throwing an evap leak code along with my loss of HP problem. I took the evap system off of the motor and it solved my problem instantly. Since then I've repaired the evap system by replacing the canister and all is well, and has been for over a year now. I still can't explain how the evap system had a negative affect on my motor. My only idea would be that while the purge was open, during non-wot conditions, I had a major vac leak.
Do not start replacing evap system parts though. Keep in mind, I was throwing an evap related dtc.

Here are a couple of questions that may help us help you.....

Do you have a check engine light? Have you had a check engine light recently that may have gone off on its own?

Is there any excess amount of smoke from the tail pipe, and if so what color is it?? Keep in mind all of these f20's smoke a bit when you get on them.

Is the car low on power throughout all of the rpm's, or is it just during v-tec?

Is v-tec engaging at 6k? If so, does it have the same growl like it once did.

Have you had a valve job recently? Those seem to make a noticeable difference for some folk.


These are some of the things you can do to further diagnose the car...

If you have an s2000 community, join them. You'll get to drive their cars and compare the feeling to yours. You may also stumble onto a mechanic that knows these cars like the back of his hand.

Get to a dyno, with a tech that has s2000 experience. Or just post your graph and let s2k interpret the results. A dyno will show if the HP is in line with other stock s2's, your air/fuel ratio's, valve float, and it can also show if you clutch is slipping.
In my case, my clutch was slipping, so I had a new one installed. HP and a/f were fine, so the dyno didn't get down to the root problem.


Have a compression/leak down test performed and post the results. This will make sure that your motor is solid.

Have the o2 sensor tested for laziness. I've seen this in a few different types of cars and a good few Hondas. They can make a car run sluggishly, but not throw any codes.


Check for vac leaks all throughout the motor, especially the breather/intake area. There are tricks for doing this, just go to YouTube.

Make sure you Pcv is in proper working order. Just a good thing to do.

That's all I can think of for right now that your mech hasn't already covered.

 

Im willing to bet heat soak is a major player in this.