Ignition Timing problem: won't advance enough
 

OK, this has me stumped, hopefully some of you with experience tuning these engines can chime in. I guess my question to you all is what would cause the ignition timing not be able to advance far enough to ahcieve the proper setting (+16* BTDC).

The storry goes like this: ('98 GSR stock w/cold air intake)
I was driving the other night, and right before I shifted into 3rd (around 6k RPM because I just heard the secondaries open) the engine stumbles and check engine light comes on and stays on. Turns out to be CEL 8 (TDC sensor in the dist.) Check the sensor resistance and it was lower than the spec. but all three sensors measured the same (360 Ohm) which leads me to believe they are still functioning. When I checked the timing with a light I found Cyl. 1 fireing almost at TDC, and maxing out the adjustment on the dist. only gets me to about 8* BTDC. This makes me believe the belt skiped a tooth, but when I put Cyl. 1 @TDC all of the cam gear timing marks line up as well. So does this mean it could not have skipped, or both cams skipped the same amount of teeth, I have no idea and am at a loss at thiss point. I almost removed the belt just to re-install and set the tension correctly, but if all the timing marks line up already would it do any good? I just need to be able to set the ignition timing correctly so I can get it back together since it's my daily driver. Sorry for the long post, I hope it makes sense to those of you out there who know how to resolve this.

The only thing mechanical that would affect your ability to dial in ignition, is the timing belt. If you are positive that the belt is installed and tensioned correctly, I would look to the distributor itself, specifically the TDC sensor.

Just to be certain, are you using the correct mark on the crankshaft? They should look just like this on the crankshaft:


-- TDC

-- 14 BTDC
-- 16 BTDC
-- 18 BTDC