VS 5.0L Manual Ute, Timing locked at 10'???

[Vipez]

Hey all... we recently bought a VS ute which runs fine but felt quite underpowered. after putting a timing light on it and running it up on a dyno the timing hoverd on 10-12btdc.

So yea does anyone have any ideas of what could be the cause?

The jumper isnt bridged for diagnositc mode and when we checked for engine fault codes it gave #12 AOK and #31 Theft detterant signal missing.

Apparently the previous owner replaced the dizzy and ignitor module not long before selling it and we have replaced plugs and leads.

 

[creastyle]

Hey there,

Disconnect the battery for 2 minutes to clear the codes. Take it for a drive and see if they come back. As for the timing, bridge out the ALDL plug to put it in diagnostic mode to check the BTDC. Should the +10.

Spin it to 12-14, bury your foot into the go fast pedal and it'll go like stink :w00t:

 

[jzt4kikz]

14's probably a bit excessive for a stock 5ltr (is it stock) - max I would go would be 12 btdc on a premium fuel. Also your timing seems fine. Code 12 is everything is ok and the theft deterrent code is just ur inbuilt immobiliser not a code so you have nothing to worrie about in that regard... You didn't say it breaks down or anything just isn't grunty so this won't be an electrical problem more mechanical... Clutch, blocked exhaust, engine that's had a hard life already ... Hope that helps

 

[Vipez]

Sorry, I didnt explain it well enough...

We had the timing light connected and did a power run on the dyno, during the whole run the timing did not budge from 10-12 degrees. No advance at all..

Also once it got to 4000rpm the timing light was flashing erratically and the curve on the dyno was very juttery

 

[Cheap6]

Unless, perhaps even if, the ignition module was brand new and not a reco. I'd be looking at that. Until the PCM switches the ignition module to "Bypass Mode" - where the PCM controls the ignition timing - the ignition module will fire the spark at the 10 degrees BTDC. The switching is on the tan/black wire, pin 'B' at the module. It will be 5V when the "Bypass Mode" is active, 0V at other times. If there's 5V on that wire at the module end (= engine running) and the timing remains fixed at 10 degrees, it's the module.

 

[BlackVXGTS]

The info below from the Holden Service Manual may help you work out the problem.

IGNITION SYSTEM PURPOSE
The ignition system controls fuel combustion by providing a spark to ignite the air/fuel mixture in the proper cylinder at the correct time. To provide good engine performance and fuel economy, and control exhaust emissions, the ECM/PCM controls the spark advance and ignition dwell when the ignition system is operating in the EST mode.
Four main components make up the ignition system for the V8 PFI engine. They are:

Distributor Assembly
Ignition Coil
Ignition Module
ECM/PCM

Distributor
The distributor incorporates a Hall-effect switch as a reference voltage pulse generator. The Hall switch is connected to the ignition module by three wires. The distributor also performs the normal distributor function of directing secondary ignition voltage from the ignition coil to the correct cylinder by means of a rotor, distributor cap, and spark plug leads. There are no advance mechanisms in the distributor.

Ignition Coil
The ignition coil is specifically designed to suit the ECM/PCM and medium energy ignition system. The coil must not be replaced with any other type of coil.

Ignition Module
The ignition module, mounted separately in the engine compartment, provides an interface between the Hall switch in the distributor, the ECM/PCM, and the ignition coil. The ignition module processes the Hall switch reference pulses, sending the signal to the ECM/PCM as a "crankshaft reference input signal." The ECM/PCM calculates the needed spark advance and dwell time, and sends EST output pulses back to the ignition module. The module triggers the ignition coil based on these EST pulses sent from the ECM/PCM.

If the ECM/PCM detects a problem in the EST circuits or for some reason cannot control the ignition system, the module is independently capable of operating the ignition system, with a fixed 10 degrees BTDC spark advance.

ECM/PCM
When the ignition system is operating in the EST mode, the ECM controls the spark timing and dwell. The ECM, via the bypass control circuit, commands the ignition module which of the two modes to operate in; the "EST mode", or the "bypass mode". If the module receives no command from the bypass control circuit, the ignition system will remain in the "bypass mode."

 

[Vipez]

Thanks guys, just the sort of information we were after. We will investigate and let you know how it went.