hi, since i changed my air filter/ plugs/ rocker cover/ gasket/ seals the car feels like it has been under-performing. when i press the throttle, it feels "heavy", like someones stuffed a sock in the air intake and its struggling to get enough air. when it used to run well the pedal would feel light and the engine more responsive, now it just feels sluggish. i notice it most when accelerating in 2nd or 3rd from 2-3rpm- it drives like its accelerating up a hill.
unfortunately i launched the old plugs and filter so cant see if putting these back will fix the problem. the new plugs are bosch super 4s and the filter/gasket/seals are fiat.
the car feels the same whether the engine is cold or warm. temperature gauge sits between half and the notch below when properly warmed up.

i tried the car without the air filter and it was obviously more responsive but still not good.

i tried disconnecting the MAF sensor and the performance didn't change.

no tell-tale lights on the dash (apart from when i disconnected the MAF.)

if anyones ever driven a car with both a short pipe between the filter and air intake system, and then a CAI kit with a long pipe, you'll notice you get better throttle response with the short pipe. well, at the moment i have a short pipe but it feels like the pipe is about three metres long.

i tried an ECU reset but no joy. I left the negative disconnected over night and when i reconnected i let it idle for five minutes and turned it off. then i just drove a la normal, however the engine never really warmed up as its only 5-10 minutes to work. is this the best way to reset or should i just drive normally after the reset?

i had the same problem with my honda integra. i'm pretty sure it's not just me as i've experienced the best side of both cars. at one point with the integra it got so bad it wouldnt even accelerate in 4th gear. never did solve the problem. changed a load of stuff and had it on a rolling road and everything.

Re: Performance problem since service- disconnected MAF sensor, no change in performance?

The obvious thing is have you checked that none of the plugs are damaged and that all the coils are seated correctly?

Re: Performance problem since service- disconnected MAF sensor, no change in performance?

hi tom, seals look good. i'm off to check the plugs now (the joy of light evenings)

Re: Performance problem since service- disconnected MAF sensor, no change in performance?

hi, all plugs look fine. the earth on the rocker cover didnt look healthy so i scratched a bit down to bare metal for good measure. the plugs werent that tight at all, could have undone them with a socket and screwdriver. blame my mate for that one. tightened them up after inspection. at first it seemed to do the trick- car felt alot better to drive. temperature gauge sat on one notch below half and didnt move. i pulled up for 5 minutes with the engine running and temperature went to halfway. after pulling off and driving it felt worse again. i timed some acceleration in gears before i stopped for 5 but like a fool didnt do them when it felt bad for comparison. i tried a 0-60 before and aft the break and got 10.8 both times. first time was with a bit of wheel spin (its raining!) and second time it bogged a bit. but then reving to 6k rpm through the gears doesnt seem to feel any different- the cars always going to feel more responsive at high revs i guess. times for acceleration through gears with foot to floor:

2nd 2k-5k 6.0sec
3rd 3k-5k 8.5sec
3rd 2k-5k 13.3sec
4th 3k-4k 7.0sec

i'll try and get some times when it feels sluggish again.