washed engine, gain in power... wtf?

[swooper]

I really can;t figure this out, and it's seriously bugging me, so I could use the collective wisdom here.

I decided that i needed to give the car some TLC, so schdueled a day and did some research - ive been changign my own oil, but this time around i wanted to do the spark plugs and the like.

The context (considered causes):
-- the last oil change had been some 8000km prior - it had looked fine ( i check every second fill up ) but it rapidly got very dark around here - i was on holiday and it had to wait another 100km. I could definately feel something was up.
-- spark plugs had been changed 20000km prior
-- i had hit a ditch a bit hard - some scrape ...maybe muffler? no immdiate difference.
-- wheel alignment hadnt been changed in 18 months. hadn't felt off.

So, im sure that made someone cringe, but i assure you, im getting into it on ontop of it now - very fun stuff.
So i've got in and gotten new wheels, aligned and balanced. I also got into the car and cleaned everything.. including the motor. It was pretty straight forward (plastic bag over the dist'cap), and added some degreaser into the mix for some areas (mainly the leaft side around the pullies and near the air-con area and under the air-intake plastic pipes). I then went on the replace the spark-plugs (only a little white on them). Changed the oil.. wasnt horrible, but deffinately due (black, not gritty), which is exactly 10-40w (valvolean protection stuff). flushed a little extra through it too. changed the oil filter... and all was well - started up happy as pie.....


That was when i noticed the engine had a louder suby tick to it.. it sounded a little more coarse. After 2 drives it seemed to subside, so i adjourned it was moisture.... then the third trip i decided to boot it... low and behold it hits 3 500RPM+ with the pedal to the floor and the engine kicks in and /muffler sounds louder. not only that, but it was absolutely flying - now hits 130 verrrry easily. I could almost say that it sounds like an after market muffler is on it. its REALLY weird. It only happens when the pedal is to the floor - it can be doing 4000rpm and its normal/quiet.

SO, after that essay, any ideas?


pics:

the car: MY2001 impreza GX 2.0L non-turbo

[taza]

Im guessing your engine is a 2.0L EJ20? I have that in my Forester. My muffler isnt stock but everything else with the motor and drivetrain pretty well is. I found changing my air intake made a huge difference to both the sound and top end revs/performance. Also changing my air filter to a K&N I could notice more power when you mash your foot to the floor. For a 2.0L its got some guts
But No I dont know why.

Cheers
Taza

[littlewhiteute]

How many kms has your motor done?

Carbon build-up within the oiling system is big issue these days.

Could have been the issue after the oil change, sticky lash adjusters.

Has your timing belt been changed at the normal intervals?

I did my WRX EJ20 with a Gates racing belt, water pump, idlers, tensioner, etc.

Has run smoother and quieter since.

[SuBaRiNo]

It hasn't gone into limp mode with the ECU has it? Any engine light?
Sounds a lot like what i experience when i unplug my MAF sensor and go for a burn in my Forester.
Noticed it using more fuel??

Dave

[Alex]

might have to wash my engine bay again to see if i can get more out of my 2l.

having said that, ive done afew minor mods to my ej20, intake, iridium plugs....well thats about it.

test drove the same model car as mine the other day, same motor, same everything, mine has got alot more grunt than it.

so maybe these motors respond better to crappy little engine mods than we all think?

alex

[El_Freddo]

Maybe you've mashed the guts out of one of the mufflers or maybe the cat converter - this will most likely remove some restriction in the exhaust system.

Any car that's near healthy will get up and boogy easily with the foot flat to the floor. It can be quiet at 4000rpm when not lead footed, this is because the burning of fuel is not really occurring in the exhaust like it does when flat footed (very rich mixture) - thus less noise for the exhaust to restrict, especially if it's now a damaged exhaust system.

Or its all psychological

Cheers

Bennie

[Alex]

thought...make sure your intake is all hooked up tightly too. This could be it (louder sound etc)

alex