Crank Angle Sensor Known to Fail?

[saturnvii7]

I have an 81 280zxt with some misfire issues. The problem is most significant right after starting the car, and I have to pop it into neutral at stops to prevent wear on the transmission until I've been driving for a couple of minutes, at that point the idle raises a little and smoothes out some.

Had it looked at by a local tech in the area who primarily works on older muscle cars and drag cars (he has a 10 second 383 chevy S-10 in his garage), and he recommended I get the crank angle sensor replaced. He basically said that it's really touchy for tuning right now, and that the best they could set the timing to was 23 degrees. I've been able to smooth it out a little messing with the distributor as well.

Does this seem like a reasonable possible cause? The part is $300 so I'm wary of buying a new one and then finding out that the timing chain is off by a tick or something along those lines. Car idles rough but cruises ok. Under WOT the misfires come back a little bit, causing the car to feel a little hesitant between 3 and 4 K RPM.

If they don't generally go bad; what's the procedure for cleaning it? I've been fighting this same idle/misfire issue since I got the car running 8 or 9 months ago and I'd kinda just like it to run correctly at this point....

[evildky]

The 81turbo is the only year and model to get the external CAS, abd yeah I suppose after a quarter century oneight wear out do you have reason to suspect the chain is off a tooth? Had things apart lately? If in doubt double check, set the crank at TDC compression stroke and check the mark on the cam gear, if it's right you might verify the distributor gear is in right and that it's not a tooth off

[saturnvii7]

Ah, no wonder why searches for info on CAS cleaning/repair/replacement are so rare; I've got the only d*mn car to have one :-)

The only reason I tend to think the timing chain might be off is that I took the car to a shop to replace the head gasket when I couldn't break some of the bolts free, and I know they replaced the timing chain after letting the tension go on it. A couple other changes they made turned out for the worse; so I'm skeptical as to whether they put the new one on correctly. That was about 10 months ago.

I'll have to look through the manual and see what I need to do with the distributor gear; I've never heard to check that before and tbh I'm not really sure where it is... Sounds like it would be under the valve cover...

I've been having a lot of problems diagnosing things with the car. 4 recirculation valves and 15 or so vacuum tubes don't help.

At this point I'm kinda wondering what I can remove that might be faulty that removing can only help. I know I've heard of people bolting over the EGR valve, should I look into other options along these lines?