05 VZ - Revving Fluctuation - Oil Leak?

[adomski]

Hi!

If anyone could shed some light on a couple of issues I've got, that would be fantastic!

FYI - Has new Water Pump, New Starter Motor, All New Premium Spark Plugs, All New Coil Packs, 2 1/4" XFORCE Dual System Cat Back Exhaust.

Firstly, I have this weird rev fluctuation issue with my VZ.
Sometimes starting off I'll keep my foot on the accelerator at a relatively low/medium acceleration, the car will set off, drop revs for about a half a second, then kick in and continue accelerating smoothly after about 2-2.3RPM.
This happens also at times when accelerating, again low/medium acceleration, when rolling. Also have noticed it wont happen if I put my foot hard down. I'm thinking it could be a MAF or Throttle Body issue? Possibly TPS.

My second issue, it looks like its been happening for a while...but I seem to have a very minor oil leak coming from the front LHS of the engine. Some on the right as well, but appears dry as though its not coming from that side.
I've been checking my oil level regularly and is not dropping at a noticeable rate. The garage floor is clean where she sleeps so I'm not overly worries, but i am a little concerned. I've uploaded a couple photos below.

Cheers!

 

[diysv6]

The reddish tinge in the second last image (?) could indicate a water leak at the front of the block.
Are you using any radiator fluid?

 

[K-BAGZ]

Definitely looks like a possible coolant leak. I recommend degreasing the engine down and giving a good clean. Then have another good look and if you can't find anything or are unsure, take it to a reputable mechanic to have a look.

1. Degrease and clean engine down.
2. Thoroughly inspect engine.
3. Rectify problem/s.
4. Take to a mechanic and ask for an inspection/quote and a cooling system pressure test.

 

[BIG_JV]

The coolant there could've just run out when the water pump was done. The first pic shows the leak above the water pump as well and it def looks like oil in that pic.

Could be a slow oil leak from the cover gasket- that's a gasket between the plastic cover and the metal of the engine, my VZ has the same leak, looks exact same as in the pic, but its really slow and an effort to fix coz the intake manifold has to come off. Wouldve been handy to fix when u did the plugs though. Don't be too concerned because its pretty minor though

Link to instructions:
http://forums.justcommodores.com.au...6/243552-rocker-cover-gasket-replacement.html

 

[Dirbatua]

yea looks like a valley cover gasket leak.

 

[rambunctious]

Re the Engine fluctuation.

Cheap possible fix, put a bottle of Injector Clean in the Fuel, it is amazing the difference that stuff can make.

 

[adomski]

The coolant there could've just run out when the water pump was done. The first pic shows the leak above the water pump as well and it def looks like oil in that pic.

Could be a slow oil leak from the cover gasket- that's a gasket between the plastic cover and the metal of the engine, my VZ has the same leak, looks exact same as in the pic, but its really slow and an effort to fix coz the intake manifold has to come off. Wouldve been handy to fix when u did the plugs though. Don't be too concerned because its pretty minor though

Link to instructions:
http://forums.justcommodores.com.au...6/243552-rocker-cover-gasket-replacement.html

Thanks, Will keep an eye on it.

 

[adomski]

Re the Engine fluctuation.

Cheap possible fix, put a bottle of Injector Clean in the Fuel, it is amazing the difference that stuff can make.

I've been reading around and it seems I'm not the only one with this issue.
People are referring this issue as "acceleration hesitation"...makes sense...but I cannot seem to find anywhere that show a complete resolution.

As of now this is what I've tried so far:
New Sparks
New Coil Packs
Injection Cleaner run with fuel (multiple times throughout servicing)
Always change oil regularly - every 5,000 - 7,500 KM
Cleaned MAF sensor with MAF sensor cleaning solution
Cleaned Intake Manifold as best i could - confirmed intake gasket/seal
23/10/15 EDIT: Replaced Fuel Filter


The next thing I'm reading is possible fuel injectors, fuel filter, fuel pump, O2 sensors. I'm a bit hesitatnt to start replacing everything

It's getting worse and worse over time and it feels as though I've lost power at lower RPM, after 3K RPM the car kicks in as though it has boost...

Any ideas would be great!

Update: When the car is in Park / Neutral the car revs up smoothly.

 

[Dirbatua]

it could be an electronic throttle issue, either throttle body or the pedal itself, especially if your stomping it they have been known to freak out or hesitate.

 

[diysv6]

Have you tried to get the car's DTCs from a Tech2 or similar scanner?

You seem to have replaced the significant parts, plugs, coils etc. Used injector cleaner regularly.

The fuel pump pressure, any leaking fuel injectors, and a fuel injector capacity test need to be done to help rule out fuelling issues.

Is the idle and engine running always smooth etc?

I had a faulty ignition coil which played up very slowly over some weeks. It went from a sluggish feel to the engine for a few weeks, to later on intermittent idle variations, to finally an obvious engine miss to about 2000rpm. Higher than 2500rpm the engine was again smooth but sluggish. No DTCs came up during this period. I was more suspicious of the fuel injectors when it first started to give intermittent missing symptoms. I checked out the fuel issues, all seemed OK. In the end, it then became so bad that disconnecting the ignition coil power connector made little difference to the idle quality. It was in #2 coil so off came the inlet manifold. Shame the coils are not all accessible, this type of faultfinding and fixing would be much easier.

That one coil when replaced made a hell of a difference to engine smoothness and pulling power. Economy improved by about 1 L/100km around the burbs.
There is no guarantee that a new coil could be not be partly faulty and not making maximum spark voltage and duration.
Did your plugs look similar when you replaced them?
My #2 plug was a bit darker than the other 5 plugs so that confirmed the coil was failing intermittently.
EVAP solenoid is working OK and the EVAP hose to the throttle body housing is not leaking etc.?