1999 VT Series II Holden Commodore SS 

5.7 litre alloy GEN III LS-1 V8,  fuel injection, 4 speed auto

Purchased new in June 99 from R & B Smith Holden.

Engine Specs : 220Kw @ 5000RPM, 446Nm @ 4400RPM


VT-SS-Front.jpg (374043 bytes)VT-SS-Rear.jpg (372430 bytes)VT-SS-interior.jpg (330229 bytes)VT-SS-Engine.jpg (384644 bytes)

General notes :

Problems so far (in the 1st 10,000 Km's) :


[ insert my questions here about auto trans and adaptive learn]

Just to clear up about Adaptive learn, as far as the trans goes the shift points won't alter (Unlike Mitsubishi) as they are programmed to a set map but line pressure is adjusted to give better quality shifts. (It works similar to short term fuel correction and long term fuel trim). The PCM monitors the engine speed and the output shaft speed to determine if the shift is occurring too fast (harsh) or too slow (soft) The PCM adjusts the line pressure to maintain the correct shift feel. So if you drive hard most of the time it will remember the line pressure to use for a good quality shift even under heavy acceleration & also if you drive mildly it will learn what pressure to use.

As far as your Knock Sensor is concerned that was a software problem. Basically the PCM runs self tests on all sensors and circuits to ensure all is correct, if it's not it will log a DTC (Diagnostic trouble code) and in most cases turn the Check Engine Light on (orange engine shaped light on instruments). We can read this information when we plug in our hand held Tech-2. In the case of the Knock Sensor it's job is to detect Detonation (knocking, pinging) in the engine and the PCM reacts by retarding ignition timing slightly, if the Knock Sensor or circuit fails the PCM detects this and because it can't tell if there is detonation it retards the timing more than it would otherwise to prevent engine damage, that is why your car felt so sluggish (sort of a limp home mode if you like).The reason it was a software problem was that the diagnostic software in the PCM was over sensitive and was picking up that the Knock Sensors were at fault when in reality there was nothing wrong with them. The problem is easy fixed as the PCM's can be flash programmed, GM put the new software on CD-ROM and we just download it onto our handheld computers (Tech-2) and then reprogram your PCM with them. Actually there is factory software available in America for huge KW outputs from the GEN-3 but they aren't releasing it for Australia.

Just for your interest you may like to know that a top of the range VT can have up to 6 microprocessors 

  1. PCM powertrain control module 
  2. BCM body control module 
  3. ABS anti-lock brakes 
  4. Instruments gauges, trip computer 
  5. SRS air-bag 
  6. ECC electronic climate control

All of these are connected by the serial data bus and share info from all the different sensors. For example the coolant temp sensor is used by the PCM, ECC & Instruments.

The GEN-3 is a little different in that it uses Class 2 serial data and every thing else on the VT uses UART serial data. Because the GEN-3 and its PCM are all directly imported from America it would too expensive to engineer a new PCM so all Australian GEN-3's have a PIM (powertrain interface module) that acts as a translator between UART and Class 2 so it can still communicate on the bus.

Hoping some of this helps and I haven't waffled on too much. Cheers


[ insert my questions here about 10K service software update, hm headers, capa airflow meter upgrade ]

Dear Michael, to answer your questions in order

1) As far as reprogramming the PCM's with the latest software we would only do it as a matter of course at say the 10k service if we get time but mostly we only do it if the customer has complained the check engine light has been coming on and the Knock sensor code is logged, or if the vehicle has some driveability problem that can't be sorted out. As far as you are concerned it might be best to ask for it to be done then you know it has been.

2) I don't mind if you use some of this info in your website, just one thing I ask is that you don't mention my name or the dealership I work at. That may sound like a strange request but some people who read it may think I'm expressing views of Holden or my dealership.

3) I honestly couldn't comment on Holden's policy as far as after-market parts and warranty, you are best to speak to your dealer in that regard. Another cop-out I know but I hope you understand my position.

4) Just one thing to watch when increasing the power output of the GEN-3 and that is you find after you have made the mods the car will go really well for a while and then you will find the power seems to drop off, this is due to the PCM trying to correct the Long Term Fuel (LTFT) Trim back to the standard power output. The only way around this as far as I know at the moment is to put a toggle switch between the battery and the PCM on the keep alive power wire, and every time you turn the car off you turn the toggle switch off for at least 10secs and this resets the LTFT correction cells back to 0. I did hear of someone sending an Australian programmed PCM over to America to see if he could re-program the PCM not to correct so much and keep the increased output but I haven't heard back on that one. I'll try and keep you posted.

Car was traded for a VX II Sedan

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