Timing drift issue

[trq-str]

Hi all,

I had a chance to get the car on the dyno last night and all was going well until unstable timing made it unsafe to continue with the tune.

Upon inspection it was noticed the timing would drift 7 degrees while locked by the ecu, turning on CAS filters made no difference to the drift.

Engine is a vr4 4g63T running the standard optical Cam Angle Sensor. The Haltech Elite 1500 ecu receives both cam and crank trigger signals from the CAS.

I have compiled a list of factors I think could be causing / contributing to the problem, has anyone here had experience with such issues?

- A potential difference noticed by the 3 separate grounds on the ign1a coil packs.
- ignition lead interference, these are custom made MSD Super Conductor leads which run a short length.
- Faulty CAS
- Timing belt oscillations, maybe time for a Crank Angle Trigger.

Thanks in advanced

 

[bazeng]

Check your settings on your haltech.

Ensure it is set on falling edge and not rising edge for your timing trigger settings.

Rising will result in the problem you state with rpm change as the sine wave shortens / lengthens pending speed of engine.

 

[bazeng]

Alternatively, it could be related to timing belt slop. Ensure that your tensioner is setup and working correctly.

I've also seen other similar issues where the CAS trigger disc has had slop due to wear and tear. This could only be revealed by disassembling the crank angle sensor. The slop was associated to keyway wear and tear.

 

[trq-str]

Thanks for the replies Baz,

Tigger is locked to falling edge in the software, Home is adjustable and set to falling edge also.

Ecu is setup to run sequential injection and direct fire ignition, could this be a problem with the stock CAS.

What Injection mode are you running with your individual coil setup?

 

[bitza]

It's the trigger disc.........only has two notches for bank (waste spark) fire.......you will need a modified disc to fire the cylinders individually (four notches)