I have a 91 Camaro z28 305 5spd with a really nasty vibration that comes in around 2500 rpm(in gear or not). I read somewhere else on this webpage that the knock sensor senses preigntion by sensing a vibration. If so, could the vibration somewhere in my engine/transmission be causing reduced timing?

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1991 Z28 305 5spd 1LE, TES headers, dual cats, 3 Chamber flowmaster, Comp cams .488/.495 212/218 the usual street racer with a stock chip.
Gained 20HP by porting and polishing my EGR passage.

Yes it can, and the knock sensors in our cars are known for false knock. You have 2 options.

A) Buy a new knock sensor

B) Bypass it like I did.

If I'm ok with no knock sensor, you'll DEFINITELY be ok. If you need instructions on how to bypass it email me. It takes 5 minutes and $.49


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91 Formula 1LE 1 of 46
305 TPI 5speed
1LE/G92/WS6

Paxton SN92 supercharger, Ford SVO 24#injectors, Crane AFPR,SLP airfoil, ported/polished plenum, March alt. pulley,Crane Gold 1.6rrs,MSD coil,MSD6AL (5400rpm limit),Holley 9mm wires,Ac delco R43ts plugs,custom chip,Bosch O2sensor,SLP 1 5/8" headers,SLP catback,shortened shifter,3:73s w/Auburn posi,180* t-stat,JET 195* fan switch, Macewen white face gauges, Autometer gauges, Zoom hi-performance clutch.

[This message has been edited by theformula (edited April 18, 2001).]

By the way you may want to use a scan tool to verify how much knock retard you are actually getting before you bypass it.

I was getting 16 degrees of knock retard at 5000RPMs. Definitely felt a difference.

how do i bypass my knock sensor? i tried to pm but cant.

Speaking of knock sensors.... is there a difference between the 305 and 350 knock sensors?

If you really want to bypass the sensor, remove the wire from it and put a resistor there instead.

The resistor size depends on what year you have.
up to -89 103 kOhms
90-92 3,9 KOhms.....

You could also desenze the knock sensor if you like.....

/N.

103,000 ohm resistor to ground?

yes, you could control measure your existing KS to be sure.

But its NOT RECOMMENDED to disconnect it!

its better to desenze it......

its better to desenze it.....please explain

as far as i knew there was a difference, because people when doing 305 tpi to 350 tpi swaps the knock sensor wasnt something they could re-use.

If you have a vibration at 2500 RPMs then you may have bigger problems than false knock.

I would NOT disconnect it. It is there for a reason. That is how head gaskets get blown. If anything you can desensitize it but in a properly tuned engine you really shouldn't have to.

I gotta say this is bad advice. Unless you know the condition of this guys engine then how could you possibly know it's OK for him to do this?

http://www.charm.net/~mchaney/knock.gif

/N.

thanks for the link

I made my adjustable with a potentiometer......

Probably better to find the problem and fix it rather than remove a safeguard that could potentially help avoid engine damage.

Yes, but after my rebuilt with new exahust it was to senzible...Now its rebuild time again so I'll se If I have to use the desenze unit.......

Sensitive is the word you're looking for. I can only say a few words in swedish, and they wouldn't be appropriate here

You must have some radical engine for it to set the knock sensor off?

Fully modded 383" with Stainless steel exhaust......

Engine is beeing rebuilt now hopyfully my next setup dont need the desenze stuff......