Rb26 Base Timing Woes

[BoostedBarge]

I've had a Vipec V44 plug-in on my Stagea 260RS since 2008. I recently changed my timing belt and set the CAS back to roughly the same position. The car has been driving fine. The other day I checked the timing and discovered it was 10 degrees over advanced, so I retarded it by 10 degrees after double-checking with a different timing light. Now the car drives worse than before. It hesitates coming on boost and makes much less power. I removed the top timing belt cover and confirmed the cam pulleys were correctly lined up with TDC. I also confirmed the cam half-moon shaped key for the CAS is still in position and hasn't broken off. So I'm at a bit of a loss as to where this 10 degrees of offset may have come from. Does anyone have any ideas?

Oh yeah, in setting the timing, I upgraded my firmware. I think I was about 4 or 5 versions behind the current release. Would this have caused any issues? In the base timing adjustment screen, the original offset (for 10 degree ref) was -82, as set by the Vipec tuner. Now it is -96 for the timing to be right. Do either of these numbers sound about right for an RB26?

One other thing, I did change the timing belt somewhere around 2008-2009 after the Vipec install and tune. I went back to the workshop and they checked the timing and adjusted the offset from -80 to -82. I was wondering in my head if the timing belt was always off by 1 tooth, but the fact I've changed the belt once already and it made minimal difference to timing, makes me think the possibilities are very slim.

Any ideas? I'm at a bit of a loss.

[Shoota_77]

My thoughts are there was possibly a timing correction built into the tune that may have been lost when the firmware was updated?

Isn't the timing offset just for the ECU to know where TDC is, not actually for setting the timing? I'm pretty sure that's the case with Haltechs but could be wrong. Worth investigating though.

Have you tried adjusting timing via the CAS as opposed to through the ECU?

[BoostedBarge]

Thanks for your reply mate. I actually took a save of the ECU tune after it was initially dyno'd in 2008. You can see the timing offset factor was -80 back then. I think the tuner changed it to -82 when I visited him in 2008/9 after I changed the timing belt the first time and he set the timing. On the weekend I initially adjusted timing by rotating the CAS. It ended up nearly at the limits of its adjustment, when it was centralised before the timing belt job. That's what raised the alarm to me. I think I had done the firmware update just before checking the timing.

[89CAL]

How did you set it? Did you lock the timing in the vipec software?

Was the idle speed correct?

What is it actually set at?

[Shoota_77]

Pull out no1 spark plug so you can then check the cam gear timing marks at TDC.

If they're right then I'm at a loss but I wouldn't be surprised if it was a tooth out based on the symptoms.

[BoostedBarge]

Solved it! The old timing loop problems strike again. I found a bit of ignition lead and connected it between the coil and spark plug, then set the timing off that. Believe it or not, it was 9 degrees off! Previously I had tested the timing loop on the little timing wire loop at the back of the engine, as well as on the low voltage wires on the back of the coil. Both of these gave identical readings. Nissan must have some fancy timing light or something. I'm pretty sure the Vipec mechanic used the low voltage wires on the back of the coil, but maybe he had a better timing light than mine.

The car is doing damn well now. Very happy. Thanks for your help guys.

[Ben C34]

Timing loop is so shit!