hey guys i have an 89 ae92 gts. im trying to adjust timing but i have a strange issue. i install the jumper on diag port to set timing but there is no change in engine speed. i set the timing to the 10 mark on the block but when i remove the jumper, the mark is still in the same spot and it doesnt go to 15 like it should. has anyone seen or heard of this issue? maybe need contact cleaner in the connector?

Sounds like the ECU did not go into diagnostic mode. Read the
following links and try again

viewtopic.php?f=9&t=11359
viewtopic.php?f=9&t=11358

Cheers... jondee86

I have struck this before a couple of times, usually only on cars where the engine has been transplanted.

I have found incorrect wiring which end up with power on the start feed wire to the ecu.
I think from memory it is the STA wire in the ECU.

This should only be powered while cranking as when there is power on this is also locks the timing to base mode,
and you get the symptom you describe.

May be worth checking.

Are you sure your jumper got a good connection in the diagnostic plugs? Sometimes the simplest......