Adjusting position of the CAS?

[kwazza11]

just wondering what adjusting the cam angle sensor on my rb20det will do? i had to pull it off to change the timing belt but didnt record its position before removing it.

does this alter the timing or anything? cause it can clearly be rotated 10mm either way.

anyone care to enlighten me on the subect?

[Revhead]

It will adjust the base timing, and yes, it does affect the running of the engine. The ECU will be able to compensate for a mis-timed engine to a point, but the base timing has to be pretty close to right for it to work effectively.

In a nutshell - fix it, your car will more than likely either ping its head off or run like a bag of crap

[kwazza11]

ok cool. so all i need is a timing light and i can adjust it.

whats the base timing supposed to be on the rb20's? do i set it to the 0 mark or does it have to be a certain advance?

oh and how the **** do i adjust it with no spark leads for the timing light pickup?

[Revhead]

I believe the base timing is around 20 deg btdc - can anyone confirm?

You'll need a spark plug lead to go between your coil pack and the spark plug (#1), then you clamp the timing light pickup to that.

[kjb_r33]

also alters the injection timing

[kwazza11]

ok thanks. i'll see if i can find a timing light and goto a workshop and get a lead made up, i'm on holidays otherwise i could of made one at work.

can anyone confirm that base timing revhead suggested?

[WazR32GTSt]

i think its 15deg on the R32...

[Revhead]

Just double checked - Waz is right, on the R32, the base timing should be 15 deg btdc @ 650 rpm.

[blind_elk]

Its 15 BTDC (for a manual). There is a loop of wire on the ignitor module (the little box at the back of the rocker covers). However, it seems to be unreliable.

The simplest way is to remove #1 coilpack from its mounting location, and you can insert a spark lead between its terminal and the plug. Then do a 'normal' timing setting off the plug lead.

[kwazza11]

i dont need to put the computer into diagnostic mode or anything? to bring it back to base timing?

[Revhead]

Ah yeah, I forgot about the little loop! But as you say it's not 100% reliable, unlike taking a reading straight from the plug lead.

I've never gone into diags mode to change my timing, but I'm in the habit of resetting the ECU after any change to engine tune. Just unplug the battery and stand on the brakes for a few seconds to drain the charge, then drive it around for a few minutes to let it relearn.

[kwazza11]

hmm.. well i put ths motor into my r31 skyline so that way of resetting the comp probably wont work.. is there any other way of resetting it?

[steve_R32]

If you are still using the std R32 computer, just unplug the battery... Standing on the brakes just supposedly drains any power left to make the ECU lose its memory. I mean, you could probably turn the headlights on... either way. Once you reconnect the battery, take it for a strap, it will advance the timing untill it pings then back it off. Apparently a common trick to get a bit out of your motor, especially once the car comes from japan, in its 100 octane tune so to speak.

[one8tsx]

Usually you need to unplug your TPS when checking timing, not sure if it applies to skylines though.

[Revhead]

Yeah I probably should have clarified the reason for standing on the brakes - that's just what I do out of force of habit. It's not the fact that you're hitting the brakes that causes the ECU to drain, it's that the brake lights are trying to draw current. As Steve says you could do it with just about any current-drawing device.

I don't think the TPS is an issue with the 'lines - as far as I know, all you have to do to set the base timing correctly is to ensure that the engine is idling at the correct revs, ie 650rpm using my above info. As I said, it's never caused me any problems just turning the CAS, but it might not be the technically 'correct' method. Anyone with a workshop manual that can clarify?