Ecotec exhaust sucking air. engine missing.

[Forbzy77]

Ecotec V6 manual Ute, has extractors. engine is missing at all RPM and when you stand 2 ft from the exhaust it seems to be blowing a lot of air, but when you put a piece of paper over the exhaust it guts blown in and out of the exhaust. likely to be an exhaust valve? or could it be an injector? its not an ignition problem cause that sounds completely different. all help appreciated

[Andrew426]

I would be starting on basic things like plugs, leads and coils.

I doubt the exhaust is blowing (or sucking) any air at all, it should be exhaust coming out of there.

[Forbzy77]

No it isn't a lead problem, i've had that before and it makes a completely different exhaust note.
The exhaust is sucking periodically (once every rev?) and blowing air/exhaust most of the time. so when paper is held over it it vibrates in and out of the exhaust.

[Forbzy77]

Anybody got any ideas? really stuck here...

[Brett_jjj]

Id get the engine compression tested,or buy or borrow a decent quality compression tester and do it yourself.This will show up any valve leakes or other problems.The minimum compression reading for the V6 is 689 KPa or a tad under 100 PSI. The maximum variation between cylinders is 30%.

[azzfox]

if the piece of paper does look to be sucking in then generally its a valve problem. you can also stick a vacuum gauge on the intake and theres a special way to read it but Ive never done it myself. maybe even do a compression test. test all cylinders dry and write down the readings. then do a wet test, pour a tiny bit of oil into the cylinders. if the readings dont increase then its a valve not sealing. good luck with it