PCV or MAP sensor issues not sure what’s next to try fix.

[Berlina&Jag guy]

Shortly after doing a service on my 06 alloytec the check powertrain warning came up and so I used a cheapo OBD2 dongle to find the fault and got a reading of P0105: Manifold Absolute Pressure/ Barometric Pressure Circuit.
Most people seem to say that this usually indicates a vacuum leak and sure enough the main PCV hose/ rigid pipe setup was broken. This is the one that comes off the top rear of each rocker cover and joins to a T that has a short corrugated pipe which connects to I’m not sure what!!? I replaced this 3-way rig with a brand new one from Sutton’s in Homebush and was certain the problem would be solved. No chance- still same error code.
Next I noticed the little rubber elbow feeding off the throttle body at the front was basically stuffed- really soft, cracks and just hanging in there. Refusing to pay $17 from the only guy on eBay who sells them I fixed this with a short length of new hose in a looping curl so it didn’t kink. Still no fix!
I’ve read quite extensively on this forum- at 211,000km I know I’ll be up for new chains soonish and I’m aware of the left rocker cover vacuum outlet being to small and this side especially being prone to gunking up so I’m guessing my next move is to pop the rocker cover and clean the gunk and drill out the spigot/ outlet.
Does anyone agree this is the best thing to do next or maybe something else I could try first?
Could I have maybe bumped or damaged the MAP wiring when I took the manifold off to do the service?
One thing, a bit silly that I did was overfill the oil when doing the service. Stupidly I drained the old oil into a plastic pan as you do then changed the filter, new sump plug and filled up with the recommended 6.5L but when I went to dispose of the old oil I filled up an old oil container and there was only about 5L so I obviously put at least an extra litre in. This has burned off now 2,000 km later and is at the right level more or less but I wondered if this overfilling might have caused some excess oil to get in and block up the PCV system?
I would be delighted if anyone was able to offer advice or opinions here.
I was hoping to do all the easy fixes first before popping a rocker cover as obviously that involves decent time and money investment.
Also, would fitting a catch can be recommended in light of this vacuum system design fault on the Alloytec?
Thanks everyone in advance.

 

[Fu Manchu]

The oil amount is fine at what you put in. 5ltrs of oil means it would have been too low.
*argument on oil starts*

I’d take off the manifold again.
Give it a good clean with throttle body cleaner.
Clean the throttle body.

Make sure you are using new gaskets on the intake manifold.

Clean the MAF sensor (no harm in it) with MAF sensor cleaner.

The air pressure sensor on the back, unplugs, so shouldn’t get damaged. Easy to replace if you need to. Get one from the wrecker or find a cheap one on eBay.

Vacuum leaks can also come from the vacuum line that goes to the HVAC and the brake booster.

Remove the booster hose at the booster, plug the end with a bolt and see if the car is happy.

Disconnect the HVAC line and plug it. See if the problem is still there.

No need to remove the valve cover.
The PCV comes out easy enough. Check the thread I did. Clean it with throttle body cleaner. Modify it.
Push it back in.

 

[Berlina&Jag guy]

Thanks Fu Manchu.
Great advice- I’ll run through all that this weekend.
I saw your post on the pcv valve mod- I’ll give it a shot as well.

I’ve got a feeling thou that the heads are full of gunk as well. Mileage has dropped to 22L/100km.

 

[Fu Manchu]

I went through that. (150-200ks to a tank)
It was a long road.
I had those codes too.
Important to understand when we get a code generated that it doesn’t necessarily mean a sensor is faulty. It also means the sensors are doing their job.

My cause was a blocked or faulty cat on passenger side and further improvements were made when I did the drives side. Used second hand ones.

Cracked exhaust manifold on passenger side.

Vacuum leaks on the PCV lines.

Faulty O2’s and aftermarket O2’s.
Water draining from AC down the O2 harness into the back of the plug.

ECM was tested and found to be fine.

Now getting around 500k’s around town on a tank after doing the PCV mod (City driving)

 

[Berlina&Jag guy]

Wow, that’s awesome info- thanks for that. I guess I’ll be going down this road as well, meticulously crossing each potential issue of the list .

I’ve now got at least four more things to look at apart from vacuum leaks based on your experiences- cats, exhaust manifold cracks/ leaks, O2 sensors.

I’ve always worked on my own cars but for the past ten to fifteen years I’ve mostly had new or near new cars under warranty so I’m a bit out of practice.
Now, having the joy of owning a 13yo I guess this sort of thing is to be expected. Now that engines and cars in general are so complex it really helps to have forums like this to share stories and information that you would normally expect to fork out cash to a mechanic.

I’ll report back here once I’ve got rid of this pesky code in the off chance that someone else can learn from my journey as well.

I have to say, while I’ve got the manifold off, for the sake of a gasket kit, I might just pop the LH valve cover off to have a look- just to put my mind at ease cause I’ve seen a dozen pictures and videos now of gunked up valve trains. Depends on the state of the PCV valve I suppose.

 

[Fu Manchu]

You can bet your arse that valves and cams have gunk on them. It’s the nature of many modern engines. Leave the cover on for the sake of your own mental health.

Been throwing around the idea of using RoyalPurple as an engine oil. High detergent oil. Start working on removing the gunk. It’s a high zinc oil though, so not sure that’s great for cats.

I removed the exhaust manifold covers to find the cracks. Was changing the starter.

Get a factory workshop manual (in pdf format) (They are about on eBay) and a significant obd reader, computer program, Tech2, or “ELM Street” (if you have a Windows PC) to see what the car is doing.

 

[Berlina&Jag guy]

So I’ve done the PCV valve job - drilled 3mm top end and pair of 2.5mm holes into the head end.
It was blocked prior to doing the mod- wasn’t stubborn blockage just needed some spray and was good to go. Took it out again 100k after doing the mod and still clear.

Unfortunately the Check Powertrain warning refuses to budge.

So far I’ve done:

> PCV mod as per Fu Manchu’s excellent post
> New PCV main hose and pipe loop
> New hose to replace rubber elbow at the manifold off-take point near the throttle body (not sure exactly what this feeds vacuum to but it’s not leaking anymore)
> isolated this and then brake booster in turn to see if these were leaking— no.
> changed oil and filter kept oil level a little on the low side of halfway.
> dismantled and thoroughly cleaned MAF sensor and all associated ducting
> removed manifold and cleaned throttle body all over- wasn’t actually pretty clean anyway.

Main thing that has improved is fuel economy gone from a crazy 22/23 L per 100km back down into the more normal 16-18L / 100km range.

This was probably the MAF clean, as remarked by Fu Manchu, the biggest result vs effort thing you can possibly do.

The mileage on the Berlina is now at 213,000 but prior to me it was one of those extremely well looked after long term family cars that only did nice long commuting runs and was always garaged and given regular fresh oil.

Will give it a few weeks and the warning may go away by itself hopefully.

If not the next thing I’m thinking is Oxygen sensors thou this seems pretty pricey for a blind stab in the dark.

3925A7B0-4E25-42CA-990D-A3D9946F6E98[/url] by Daren Jensen, on Flickr[/IMG]

 

[Fu Manchu]

There is a good thread on testing O2 sensors. It can be done with a multimeter which is enough to give you an idea of their effectiveness.


Will find some info later for you.

They aren’t too bad to remove.
Drivers front was the trickiest but the others are easy as.

200000 plus from them is a good go.

 

[Fu Manchu]

Going through the Holden DTC list on the factory manual in the diagnostics bit and there is no P0105.

Codes used are P0103, then jumps to P0106, P0107, P0108.
The P0105 is not used by Holden on the VE.

This might be due to an incompatibility of the code reader you have. Not all will read the Holden GM codes correctly.

Try disconnecting the battery, unplug the sensor on the back of the intake. It is a simple one to remove and reads the barometric air pressure external to the cars engine. Give the connector plugs a clean out with Contact cleaner. Let it dry. reconnect the sensor and refit, then reconnect the negative terminal in the boot.
Can't hurt.

*Edit, I've found some cool stuff. Things like how someone talked about putting their foot flat to the floor and the car would start. Well the sets the flooded mode and the ECM will not fuel the injectors to clear the the over fuel condition. So there we go. doesn't help here but answers a question buried in the forum.

From what I'm reading, you can't do the MAP sensor tests yourself. You can do everything mentioned so far because they are all also mentioned when resolving P0106.

Throttle body is one source of problems. Worn shaft. If it was cleaned and then the problem happened, was the gunk sealing it up a little and covering the fault?
It should be clean regardless because a gunked up intake can also be related to this. So make sure is all clean. The intake should be cleaned. Throttle body cleaner and the hose, leave it in the sun to dry out. New gaskets.

Maybe try getting a MAP sensor from the wreckers or on the eBays. Parts swapping, yes, but they should be cheap enough. Maybe even try US Amazon and a seller who sends to Australia. Cadillac CTS 3.6ltr is what you search for. Same motor.

 

[Fu Manchu]

Another place there can be vacuum leaks hidden is the ports themselves on the sides of the intake manifold. Some of the plastic ports have a seal, it gets deteriorated. Some pull out and some unscrew out.
These can be replaced with threaded brass ports that you get from the parts shop. There is a thread with photos and part numbers. Cheap to do.
They thread in. The intake manifold needs a bloody good clean and solid hose out/flush after that to get little filings out.
*DO THIS OFF THE CAR! (yes I yelled)