Performance Related – Holden Commodore VZ SV6

[Jeremy Presnell]

Hi Guys,

Its my first thread on the forums.

I’m in Australia and have a Holden Commodore VZ SV6.

It is a GM LY7 3.6L V6 190KW engine with VVT on both intake and exhaust.

I have a bit of a sluggish performance issue and have replaced a few items to resolve the issue and also due to age of them/condition/maintenance interval.

Spark Plugs replaced
Fuel Filter replaced
Fresh engine oil (i do this every 7,500-10,000km)
Throttle Body removed and thoroughly cleaned
2 Intake hoses replaced (had splits)
EVAP Solenoid replaced (was leaking)
02 Sensors replaced

I have a couple of issues, the biggest being the car runs really sluggish once warmed up, if i get in the car, start it and drive off, it runs pretty near perfect till it starts to warm up.

When its running sluggish it requires the throttle to be pushed down a bit further to really go and and light foot driving feels worse than my partners 4 cylinder.

If i try to take off at lights or speeding up onto the highway/freeway/motorway it runs sluggish then will rev higher up then roar off.

If i WOT the car picks up and takes off, obviously doing this all the time is not a good idea.

My fuel consumption due to this has suffered somewhat.

I noticed when checking stuff over the other day, the intake camshaft position sensor actuator solenoid on bank 2 (passenger side) is leaking oil around its seal.

As a matter of caution i am going to replace the solenoid and seal mentioned above.

I have been taking some logs of OBD data via my Android phone using a Bluetooth OBD2 adaptor.

I have attached some Excel spreadsheets of recent data log runs.

The one thing i have noticed, bank 2 fuel trims look to be a little off and for the most part bank 1 runs fine.

I have tried to do a log for TPS sweep, but it looks fine from the readings.

Also to note, when at lights you can feel the car going from a ok-idle to a pretty rough idle however the RPMs don’t appear to move that much and via OBD only show around a 5-20RPM fluctuation.

Hoping someone can give some further suggestions?

Thanks.

EDIT:

Just also, i’ve gone through all of the performance issue testing on this and many others including testing coil packs (this was before i could see fuel trims) and checking for vaccum leaks, etc.

I also forgot to mention, the reason i was checking TPS also, i am having an odd issue mainly when either suddenly accelerating or slowly down suddenly from high speed (eg. from freeway/highway/motorway) where the RPMs will stay up in the high range, as if my foot was on the pedal.

From what i have read this issue is commonly either TPS, which since my car is fly-by-wire its all contained in the 1 costly throttle body unit.

Also read this could be a CAM sensor issue?

Attachments:

• Torque.zip

Topic

[college man]

here is a link for performance issues. what year is the car?

http://www.ericthecarguy.com/faq/solving-automotive-performance-issues

[Jeremy Presnell]

[quote=”college man” post=89835]here is a link for performance issues. what year is the car?

http://www.ericthecarguy.com/faq/solving-automotive-performance-issues%5B/quote%5D

I’ve gone through most of that troubleshooting and cannot find anything, except for the cam position sensor actuator solenoid (as its listed in the workshop manual)

Its a 2004 model.

[college man]

Try spraying the ignition wires with water to see if the engine
starts running rough. If you can turn the lights out and look for
arcing.

[Jeremy Presnell]

[quote=”college man” post=89946]Try spraying the ignition wires with water to see if the engine
starts running rough. If you can turn the lights out and look for
arcing.[/quote]

Car is coil pack on spark so no ignition leads.

[college man]

Try the power balance test. Also try cleaning you MAF/inlet air
temp sensor.

[Jeremy Presnell]

[quote=”college man” post=89951]Try the power balance test. Also try cleaning you MAF/inlet air
temp sensor.[/quote]

Did the power balance test alreay and cleaned MAF(IAT contained) also.

[Jerry Jones]

A faulty ignition module could cause those symptoms. I tend to think college man is on the rite track. I sounds like an electrical issue.

[Jeremy Presnell]

[quote=”bustedbolts” post=89963]A faulty ignition module could cause those symptoms. I tend to think college man is on the rite track. I sounds like an electrical issue.[/quote]

I have swapped out each coil pack with another brand new coil pack to see if its made any difference at all, which was no. (1 at a time, not replaced them)

I also measured the resistance of each coil pack, which were all in spec.

Looking at my OBD data (excel sheet) i can see bank 2’s fuel trims are off, regardless of ignition, fuel trims should not be running lean.

[Lorrin Barth]

For some reason I can’t see your spread sheet. Do coolant temperatures look right?

[college man]

see if this helps for sensor testing.Alot of problems with cam
chains. Are you hearing any metal noise?

http://www.tech-online.com.au/TechOnline/articles/a5/a59f3cc4-5590-4981-98ca-58646f127efc/3192.pdf

[Jeremy Presnell]

No i don’t hear any chain noise, i know the chain can become an issue, at this stage assuming mine is fine.

My car temps appear to be normal, however i don’t have a ‘standard’ temp range info to compare to.

Car typically sits between 90-105c when driving around.

[Lorrin Barth]

I was thinking that the coolant temperature sensor could be giving some false indication to the fuel injection computer but the temps you report are normal.

[Jeremy Presnell]

[quote=”barneyb” post=90033]I was thinking that the coolant temperature sensor could be giving some false indication to the fuel injection computer but the temps you report are normal.[/quote]

Yeah, any further things to try?

I know that the camshaft position sensor actuator solenoid is leaking, but i’m just going to get a new seal, pull it out, clean the oil out of the soleoind and put new seal in and see that goes.

Not sure if that would cause the issue though?

I get no CEL or engine lights so i’m not sure.

[EricTheCarGuy]

As pointed out in the article College man posted, start with the basics and don’t ignore the evidence. If you didn’t find anything with the power balance test, the it’s likely you’re OK and there would be no need to swap out ignition coils. If however you have a mechanical issue like a timing chain problem, it may not show up in a check engine light. In that case you would have to do an exploratory to assess the condition of the timing chain. In your situation, I might check for a restricted exhaust. This can be more of a problem after the engine warms up. In the article there is a video on how to check for this but I’ll post it here also. Lastly, don’t rule out a transmission problem. Come to think of it, it could also be a brake problem like a caliper hanging up. In short, you have to take a systematic approach and try not to leave anything out. Pay attention to the symptoms and the evidence you find. Avoid assumptions like a cam sensor that’s just leaking oil that you don’t have a code for.

Keep us posted.

[Jeremy Presnell]

The transmission was completely rebuilt 23,000KM ago.

Actually, this morning i’ve dropped the car off to transmission specialist for its 20,000km interval service, he will also be checking it over for any issues and let me know.

I did advise him of an issue which has only occurred on a number of occasions, however only started happening after the sluggish/odd idle where when cruising between 60-75 and about to go up a hill, the transmission feels like its still in torque convertor lock and all power dies until it then drops down a gear to get the hill, whether this is sensor related or some other transmission issue i am not sure, but i gave this information to the transmission specialist to have a look for me.

I don’t know of any simplistic way of testing the timing, using OBD all i can see is timing advance degress, not sure how to actually check them.

I don’t have any chain rattles like others have (plenty on youtube).

Using your videos (i went through your troubleshooting) i checked vacuum using OBD and i cannot see any vacuum issues such as leaks or restricted exhaust.

I also did a heat check at both inlet and outlet of both CATS as per your videos.

When i replaced brake pads 2 weeks ago, there was no issues with the calipers, cleaned them and replaced the slider grease also.

If i put my AC on, the car idles a lot better and on occasion can run a tonne better also, if i suddenly turn the AC off after its been on, RPMs take a small dive and the car makes a stutter.

The power balance test didn’t give me any noticeable change in RPM when pulling each of them out, but i can see bank 2 fuel trims always sitting lean and the ECU compensate by using more fuel on that bank.

I might try swapping over the injectors from bank 2 to bank 1 and see if the fuel trim readings move with them, if it does that should be injectors if it, something else.

I’ll go back through and check these things again on the weekend along with checking all of the sensor readings again with my multimeter.

[Author]

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