Ok, I'm getting occasional knock retard on my '91 Formula (305 TPI with only 36,800 original miles).

The car runs fine and strong for a 305, I might go a week or two just fine. Then out of nowhere, retarded timing and SES. I don't hear any knock and if I shut the motor off - wait a few minutes then start it again, I get normal power and KR may come back in 5 min, or go a week or two with no problem! Is my knock sensor torqued too tight? (causing over-sensitivity?) What can I do??

p.s. I did do a diag with a GM tech (and it is the knock sensor). He said to replace it. But if I could wrap a few layers of teflon tape on it would that actually de-sensitize the damn thing? Please help! Thanks

 

You could try kluding around the problem by wrapping the threads w/ extra tape and putting it back in loose, but in general, if it is giving you major KR and throwing acode (and there isn't a horrid exhaust leak and/or a bracket banging on the block) the sensor is prolly shot and is reporting knock whenever it feels like it. In which case, the temporary solution (as well as letting you diagnose a true knock condition) would be to bypass the sensor w/ a 3.9k ohm resistor, and then replace it ASAP. At least w/ it bypassed you won't get false KR so it will run fine, you just have to listen for detonation and take it easy (or even better, work on it) if you get some.
...ed

edit, forgot to mention this all assumes that the ESC circuitry itself isn't bad, which is also a possibility.
------------------
Ed Maher - Moderator @ The TPI & Carb Boards
92 Z28 Convertible - Quasar blue / Tan top
LB9 4L60 GU2 G80 - stock, soon to be sleeper
-=ICON Motorsports=-

- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die

[This message has been edited by Ed Maher (edited August 22, 2001).]

 

Thanks Ed,

I'm gonna just replace it and see what happens. BTW, is there a less sensitive sensor out there? (either GM or aftermarket?) I also read on a forum that there may be a difference bewtween the LB9 and L98 knock sensors. Is this true? Thanks for responding.

Lance