VR v6 all 6 spark plugs carboned

[Skylarking]

..I was hoping to measure voltage or ohms resistance when at operating temp to see if those values were with in spec...

Pity it doesn’t work that way as that would be easy

The only true way to test performance of an O2 sensor would be to have a test engine with a high quality high speed O2 master sensor and a second O2 sensor port near it. The sensor under test is installed in the second port and the test engine run and the mixture controlled so that we can check the test sensor wave form against the master sensor. That’s the only true way to check the sensors slew rate. I’ve never seen such a setup. In any case why bother, sensors are cheap (or so they tell us).

But nobody does such, instead they use their vehicles engine and the fact their ECU will force a rich to lean change every so often (300 ms). As long as the sensor responds to this closed loop behaviour all is usually ok.

The sensor could still potentially have some sort of offset fault and thus gives false info to the ECU despite following high low closed loop transitions. In these sorts of cases, maybe the STFT and LTFT could give some hint if some such offset reading is occurring (along with plug condition, etc) but I’ve not delved into it so much.

In one sense, it’s like knowing water boils at 100C. But does it. Water’s boiling point relates to altitude so at 5000’ water boils at 95C Hint don’t check your thermostat at altitude

Guess what I’m saying is that it’s a complex issue to test and calibrate devices or sensors.... it’s a whole field in its own right. Luckily near enough is good enough as far as mechanics and old engines are concerned

It all gets a little complex, especially in an old engine, which is why one needs to go back to basics and check compression and other issues related to the mechanical condition before diving into electronics since running rich may be more than just an O2 sensor issue (and don’t discount wrong heat range plugs as another cause of plug fouling)...

 

[pete30nz]

I'll get hold of a compression tester, it will be a bit of time to get one.
Will post back when I check compression.
It's an ongoing thing, so any other input is welcome.

Cheers
Pete

 

[pete30nz]

Hi people,

Further inspecting the VR v6 lead to finding what's in todays photos. I know it's to do with fuel/tank. Bit what is the exact purpose for it.

Can this add to spark plugs fouling/carboning?
Or should I make a new thread for this?

Cheers Pete

 

[Skylarking]

Hi people,

Further inspecting the VR v6 lead to finding what's in todays photos. I know it's to do with fuel/tank. Bit what is the exact purpose for it.

Can this add to spark plugs fouling/carboning?
Or should I make a new thread for this?

Cheers Pete

Fuel, tanks can’t vent gasses directly to atmosphere as it’s a pollutant. So they have to have some sort of gas charcoal canister that absorbs the gasses boiling out of the fuel tank and then bleeds those into the intake via a ECU controlled solenoid. Under some conditions the tank must also be bled directly to the atmosphere for safety (since you don’t want too much pressure build up).

Fuel tank breather is described in this thread (look at post 13 pictures and later...) but I’d think you’d get more detailed info from the Holden workshop manual linked on some post somewhere in these forums.

Poorly operating charcoal canister/purge valve can cause running/idling issues but I’ve never looked into it other than reading on these forums.

Do you need a new thread for this? I don’t think so but thats just me and i can honestly say I’ve no recollection of the forum rules

 

[pete30nz]

Fuel, tanks can’t vent gasses directly to atmosphere as it’s a pollutant. So they have to have some sort of gas charcoal canister that absorbs the gasses boiling out of the fuel tank and then bleeds those into the intake via a ECU controlled solenoid. Under some conditions the tank must also be bled directly to the atmosphere for safety (since you don’t want too much pressure build up).

Fuel tank breather is described in this thread (look at post 13 pictures and later...) but I’d think you’d get more detailed info from the Holden workshop manual linked on some post somewhere in these forums.

Poorly operating charcoal canister/purge valve can cause running/idling issues but I’ve never looked into it other than reading on these forums.

Do you need a new thread for this? I don’t think so but thats just me and i can honestly say I’ve no recollection of the forum rules

I wonder if this will create a miss. I'll find out offer lock down, when I replaced the vac hoses.
Do you know if these ones are very long

Pete