What would cause this noise?

[waffles666]

I have a 1996 VS Executive II 3.8 V6 Auto. What would cause a misfire (only happening on the left hand side) intermittently at high revs (3000 or there abouts when the car is about the shift) which gets worse the hotter/longer you drive? I have replaced the spark plugs because i don't have no experience with cars, should i replace the leads and coils next or am i completely off track?

p.s After driving for about 30 min the car has no power and barley responds to the pedal for want of a better way to describe it, it sounds like i have a mini blow off valve front left.

 

[hako]

Check for fault codes first: https://forums.justcommodores.com.au/threads/checking-error-codes-vr-vs-revised.22307
What makes you sure the misfire is on the left hand side?

 

[waffles666]

Beep codes

It was originally beeping a 76 which is air/fuel mixture not equal on left/right side but after i reset it by disconnecting the battery the code hasn't come back. and the sound is very distinctively coming from the passenger side. I am replacing the leads tomorrow morning and have some second hand coils coming in because they were only 50 bucks.

The sound is only there when the car is moving by the way and under load like going up a hill or from a standing start and gets worse the longer the car is driven.

edit: I said the sound is a misfire but i don't know much about cars so if a misfire only on one side of the engine doesn't make sense then its probably not.

 

[MY-42-VT]

aghhhh i know what your probly is buddy

injectors need cleaning, run a bit of injector cleaner through her, if it dosn't work or makes it a bit better, replace the injectors....that should be your problem mate

 

[waffles666]

Injectors

One of my mates said that was a probable cause as well, I will still get the leads tomorrow and the coils are ordered already so no harm replacing those anyway and if that doesn't fix it i will drop it in to the mechanic for new injectors sometime this week and get back to you.

I have already run a tank of injector cleaner through it and its much the same...possibly slightly better bit hard to tell.

p.s anyone know what i would be up for for new injectors?

 

[MY-42-VT]

mmmm including labour...i'd take a stab at about 200-300....at the max 350 .... but yea thats just what i think....in the perfect world haha

 

[westbad]

new injectors will set you back around $200, i should say it would be the leads or a faulty coil pack making it miss fire..

 

[hako]

You may also have a vacuum leak - maybe when the engine warm the hole/crack/split or whatever where the vacuum is leaking gets larger and sounds like a blow-off valve......maybe the inlet manifold is warped on the passenger side allowing air to be sucked in...warps more when hot and the extra air would kill the performance. Just a guess.

 

[waffles666]

Vacum Leak

what if i was to spray something near where the manifold came out of the engine after a hot drive then you would be able to see if it was sucked in, normally the engine should be air tight right?

 

[hako]

That may work as long as the engine is missing at that time but I'm not sure what you could spray that would plug the hole/crack/gap and not catch fire on the hot engine. . Normally you would get an oxygen sensor detecting a weak mixture. I'd instal the coils and leads first and see if that makes a difference. The strange bit is that noise you are getting.