WH Statesman 3.8Ltr 6 cyl with a Dangerous issue

[Immortality]

Well Bathurst is over and today I worked on the WH Statesman 3.8L. today I replaced the MID Lim Gasket and I was very particular in fitting it as I checked everything. I also Checked whist I have the lid off the manifold I Checked the Purge Valve and its pipe to the throttle body and I sucked into it and found it closed and the hose stuck to my tongue so I have no vacuum leaks there.
STARTED THE CAR.
When I started the car the car does the Same thing. It went to 1200 RPM immediately and stayed there for a minute or so and I turned the car off and started it again after 2 minutes being off and this time it started normal at around 1000 RPM and slowly went to 850 or 900 RPM,,, GOOD but after a minute it went to 1200 RPM and stayed there for 2 minutes then 1100 RPM then 1200 RPM then it went to 1100 RPM than back to 850-900RPM. WTF??

WHAT IN THE F..K is going on.
I checked the Code ( Battery was disconnected for 3 hours whilst I did the LIM replacement) and the CODE was FLASH FLASH FLASH FLASH FLASH FLASH FLASH FLASH FLASH FLASH..... PAUSE ....than another FLASH FLASH FLASH FLASH FLASH FLASH FLASH FLASH FLASH FLASH..... PAUSE.... then FLASH, then PAUSE than FLASH FLASH. Now in my book that's 0012 which means the car is fine and running good,,,, BULLSHIT!!

After this I decided to remove 3 spark plug out ( two on one side and one on the other side ) and considering the plugs were replace by me around 1800 K ago around two mounts of driving I found them WHITE to a point (LEAN) that I could put them in the box and sell them as new again. Yes You had to look twice to see any marks on the Centre porcelain to see if they have any evidence of browning on them.
I checked Two on the drivers side, the back and middle cylinder and on the other side I checked the front on the Passengers side. remember No code was spat out to me.
I need more test tool to find this issue with this car but I dont want to by them as I have spent to much money on a car that is not mine.

I just about to give up on this statesman, I have spent more time on this compared to me Cheap VE fixing everything.

Reading plugs on an EFI engine is not like reading plugs on a carb engine. EFI has lean burn so the plugs stay clean when it's running well. Our old VS always had clean white plugs at 10K intervals.

The change in idle suggest either the PCM is getting a dodgy signal from a sensor/dodgy wiring or the PCM itself is stuffed.

 

[Trevor loves holden.]

Has he got car insurance , wink wink, I wounder if the IAC housing is damaged, maybe get a second hand T.B with the sensors and swap it out, have you checked with a multimeter on the IAC if the value was changing when the rpm changed same as TPS, this will tell you if the ECU changing the revs or something else is like injector or air leak. The O2 sensors, MAF, TPS, IAC or work together, maybe a loose or bad connector.

 

[VFSV6FORME]

Has he got car insurance , wink wink, I wounder if the IAC housing is damaged, maybe get a second hand T.B with the sensors and swap it out, have you checked with a multimeter on the IAC if the value was changing when the rpm changed same as TPS, this will tell you if the ECU changing the revs or something else is like injector or air leak. The O2 sensors, MAF, TPS, IAC or work together, maybe a loose or bad connector.

Yes used Multi Meter to test the TPS. At stop position its 0.5V and at full throttles its 4.5 Volts and I moved it up and down for as slow gradient from up to down. NO FLAT SPOTS.

 

[VFSV6FORME]

Reading plugs on an EFI engine is not like reading plugs on a carb engine. EFI has lean burn so the plugs stay clean when it's running well. Our old VS always had clean white plugs at 10K intervals.

The change in idle suggest either the PCM is getting a dodgy signal from a sensor/dodgy wiring or the PCM itself is stuffed.

Yes the carb days were good but I fully understand the EFI and they can make the engine run lean but how lean is to lean.
I agree with you as there might be a Dodgy signal or a poor connection or the PCM is stuffed.

What other sensor can cause this? 02 sensors, Temp Sensors. What about the Fuel pressure? what pressure should I have (average)

 

[VFSV6FORME]

For the engine to rev it needs more air to which the PCM then adds fuel. There is also a limit to how much the O2 sensors can adjust the fuel trims.

I still think there is a vacuum leak but where. Can it leak around the Injectors?manifold (the hole) itself and make that bad itself to give up and down idle RPM. Maybe I will start the car and add soupy water there around the injector to see if it sucked the water in.

Talk about the Injectors the top/mid Manifold and Fuel rails govern how much the injector seals into the bottom manifold.

 

[Immortality]

Yes, it is easy enough to pinch an injector O ring when putting the plenum back on but I think it would idle high continuously. use some wd40 and spray around the injectors and see if the idle changes. I always recommend (and use) a little lube on the injector O rings before fitting.

 

[VFSV6FORME]

have you checked with a multimeter on the IAC if the value was changing when the rpm changed same as TPS, this will tell you if the ECU changing the revs or something else is like injector or air leak. The O2 sensors, MAF, TPS, IAC or work together, maybe a loose or bad connector.

No Might have to do this and check the IAC when the car is running. At Idles its 0.5 Volts so I would say it has to stay 0.5Volts @ 900 RPM but if the Voltage goes up to 1.8 Volts and I dont touch the throttle, well that different and can be a issue.
By the way I use a Small needle to pierce the end of the wiring for the IAC Valve with out damaging anything. the Needle goes parallel with the wire on the harness itself

 

[VFSV6FORME]

Yes, it is easy enough to pinch an injector O ring when putting the plenum back on but I think it would idle high continuously. use some wd40 and spray around the injectors and see if the idle changes. I always recommend (and use) a little lube on the injector O rings before fitting.

I used white grease to lube the injectors

 

[VFSV6FORME]

Yes, it is easy enough to pinch an injector O ring when putting the plenum back on but I think it would idle high continuously. use some wd40 and spray around the injectors and see if the idle changes. I always recommend (and use) a little lube on the injector O rings before fitting.

If I use WD 40 if there is a leak the WD 40 should get sucked in. what about penetration, Possibly injectors not pushed in enough? Dont know if the top bit floats in or out. All I know is the injectors can go left and right

 

[Immortality]

Injector depth is not adjustable as they are fixed to the plenum so height should not be an issue unless you have added something in between the LIM and plenum. Crap in the injector holes may cause a leak if the O ring is damaged.