Falter when revving

[alex2_s]

Hi, '96 VS Acclaim Ecotec (140 000kms) is all going good except.... it idles fine, however when giving it a sharp rev it falters for a second before revving, and makes a 'sucking' noise from the air filter on closer inspection. It also seems to be making an audible 'sucking' noise even when idling (but not so loud) from the air flow pipe (not heard until its recently started doing this?)

Accelerating gently (drive or neutral) doesn't cause any problems, it just falters on a quick rev.

Any thoughts?
thanks in advance

[Paiste402]

how old is your air filter? it might be thicker than a pillow and the car cannot get the air it needs when given the boot. When given a big rev does it smell like its running rich? Cause then it will be burning more fuel than air and have a poor mixture.

$20 for a good air filter and they need to be replaced regularly anyway.

thats my guess on it, im sure im quite wrong tho.

[Man]

have an exhaust mod? has the airbox been played with?

[Cursed CX8]

im thinking just give it a good service,
- new plugs and leads
- new oil and filter
- new fuel filter - possible cause of problem
- New air filter or wash the K&N what ever you have - possible cause of problem
- Run some injector cleaner for a few tanks of fuel

other than that ill have a think about things

[alex2_s]

Hi, brand new spark plugs and leads (gapped correctly)... brand new air filter, oil and oil filter :S Exhaust and air filter are all stock.

I'm going to replace the fuel filter and see... thanks for your replies.

[Cursed CX8]

could also be a dirty maf, dodgy TPS etc. Just a thought, see if u can drive a car with the same engine to see if it behaves differently, also check the fault codes

[alex2_s]

new fuel filter still does it

[greenacc]

i reckon its normal to some extent - the sucking noise anyway, cos it needs to take a big mouthfull of air for the revs to climb at WOT. could have an air leak where the duct fits onto the filter box ? a weak coil or dirty injectors ^^^ would also do it.
Wat brand air filter?

[alex2_s]

yeah i was really just more concerned about the 'delay' when you give it a rev. It's a holden (ACDelco) air filter.

[Cursed CX8]

how long is the delay? to some extent id say its a fuel or spark issue. If its spark then id think its insufficient spark, if its fuel then its either running lean or rich, if its running rich the car will be chewing fuel like crazy and there may be black watery discharge from the exhaust. If its running lean the exhaust might pop and backfire the car will run HOT or even have detonation (pinking) and high revs or under load.

Id still suggest running some injector cleaner or even a complete upper cylinder treatment to clean everything out. Also give the throttle body a little clean.

Did you just buy the car or have you owned it for awhile? whats the service history like?