Adjusting timing for fuel

[Slimg60 0]

My engine was mapped with a tank of BP ultimate and it ran sweet. Yesterday I had to put in Tesco 99 and since then it's started to stutter a little.

When my engine was fitted I had a knob installed to allow me adjust the timing.

Can I adjust the timing to compensate for this fuel? Am I right in thinking I should retard it slightly?

I'm only asking as I dont waant to prat around with it and break something.

 

Cheers

Slim

[Toad 0]

Are you sure your knob isn't for adjusting boost?

[Slimg60 0]

I have one the for adjusting boost, as it was on Simon's car.

The timing adjustment was something additional that was put on during the swap.

[Toad 0]

Cool.

 

I don't know what to suggest really, I'd be a bit concerned about fiddling with the timing.

[dragon green 4]

Is it an adjustable boost retard ?

MSD or similiar ?

[Slimg60 0]

Cool.

 

I don't know what to suggest really, I'd be a bit concerned about fiddling with the timing.

 

I i think it's for the ignition timing, +/-7 degree's I think.

[Diamond Hell 0]

What's the management on the motor?

 

Proper management should be able to handle advance/retard according to the grade of the fuel, using the lambda and knock sensing systems.

 

If you've not got something controlling the management properly you're going to be scratching around in the dark, mostly finding your arse crack.

[Slimg60 0]

the engine is running Haltec E6H management.

[Slimg60 0]

Sorted, turns out Haltec doesnt like Tesco 99.

[dirtytorque 0]

lower octane fuel would require less(retarded) timing.

Most after market engine management systems do not have knock sensing and just rely on the car being sensibly mapped with for chosen fuel in mind.