Erratic Engine Timing

[shaneAS97]

my 1996 gts25t has had a rough idle and a intermittent misfire for awhile. i replaced the spark plugs about 600kms ago and it ran fine for awhile but it started to run bad again. i plugged in my consult and looked at some gauges. i noticed that the timing degree before top dead center jumped around from 10 degrees up to 15 degrees. everything else seemed fine. i am wondering if it could be the timing causing my issues, and if so what would be the cause of the timing issue.

The car is relatively stock has a cat back exhaust with cat delete and a intake.

I videoed the timing gauge jumping around but the video is to big to upload.

thanks in advance.

shane

[Ben C34]

That's normal for the timing to fluctuate.

The ecu uses timing along with aac to control idle. It will only be locked to 15 with the tps disconnected.

[zoomzoom]

It will reduce timing below 15 degrees if the engine is drawing in too much air at idle, in order to reduce the engine speed. Trying adjusting the screw on the aac valve while monitoring the engine speed and timing with consult.

[Ben C34]

All ecus use timing adjust to control idle along with aac valves. The timing is a much quicker way to get a result, its not abnormal.

[HYBRID VL]

these guys answers sound on the money though my old man had a similar issue in his Nissan patrol it was actually the dizzy turning with the engine movement.

When he got it tuned they over tightened the dizzy bolts threaded them and they wouldnt grip anymore and came loose took a while 2 find it cause everytime we checked it the timing would be out we would tighten it and it would be cool until some engine vibrations and loosen again.

I know its a CAS on the RB's but worth a look in just thought it might help.