rough idle on my vt any ideas?

[purekiwi]

hi guys ive got a problem with my 99 vt ecotec commodore idle running realy rough i have changed the plugs and leads thinking that my have been the problem but didnt seem to make any differance i just want to get it sorted as im not sure if its doing any damage? thanks in advance

[soop]

Little more information, does it do it under load at all?

I.e, when you apply throttle does it misfire and pop through the exhaust?
Does it try to stall at all?

[Cameron P]

if its only on idle it could be the air flow sensor?

[DLFHUB666]

Do the v6s have a PCV hose? (sorry dont know much about the v6s),if they do thats what my money is on.

[purekiwi]

its fine as soon as im driving it doesnt miss a beat or missfire at all its just when its idling in neutral at the lights it runs rough and every now the revs will jump down real low for a second kind of close to stalling,and if i sit in park with the engine running for over 5mins the engine light comes on and then when i drive ten meters it dissapears again im not sure if that has anything to do with it or not just thought it might help for you to know

[soop]

Replace the o2 sensor and see how you go.

Might even be a TPS issue.

[purekiwi]

thanks guys ive got it booked in to get a service and the breaks done on monday so il tell my mechanic to have a look i just wanted to get some advice befour i took it in

[wrx884]

do a self diagnosis and see if u get a EGR position fault (code 29). if so make sure the pintle valve isnt sticking open with any debris. mine did this a lil while ago n made the car sound and idle like it had a lumpy cam in it lol

[brett_d]

its fine as soon as im driving it doesnt miss a beat or missfire at all its just when its idling in neutral at the lights it runs rough and every now the revs will jump down real low for a second kind of close to stalling,and if i sit in park with the engine running for over 5mins the engine light comes on and then when i drive ten meters it dissapears again im not sure if that has anything to do with it or not just thought it might help for you to know

Hi - just read your post which describes exactly what I am seeing with my VT. Can you tell me how you went with sorting it out? Cheers

[kriis.xx]

Having the same problem after changing the intake manifold gasket so I'm assuming this could be a top end engine problem but I've triple checked all the sensors and I'm at a loss

[Giant]

Could be faulty fuel pump or dirty fuel filter if it goes away when you start driving and is only on idle

[SavVYute]

(1) I'd have a look for a disconnected or split hose somewhere.
Can you hear anything hissing slightly in the engine bay?

(2) Could be a dirty throttle body. Give it a spray and wipe out with throttle body cleaner.
That will help too if it is the idle air control valve (IAC) sticking.

(3) Your throttle position sensor (TPS) might be sticking or it could be dodgy.

(4) Put a new air filter in and see if this makes a difference.

(5) Did you fit the correct spark plugs NGK-BPR6EFS-15 and are they gapped correctly? 1.5mm.

(6) Fuel filter

Try all the cheapest options first though.

[WhisKiz]

I had a similar problem and funnily enough it turned out my cats were blocked.. (catalytic converters)

[CHA53R]

Check codes, might be the answer in there if not clean MAF, change plugs and leads then see how it goes, if runs fine fir a little while and does it again change coil pack.

[cmarico]

Had the same problem. Check the Purge Hose under the throttle body. Mine had come undone and gave me a rough idle and slight hiss. Plugged it back in and zip-tied it on, and running perfectly. Takes 10 seconds to check and nothing to fix.