I have been working on my friends car for the last week installing a nitrous system on it. Now that i have it installed i plugged in diacom just to find out that his knock sensor was going off already without the NOS
Any way the only way i seem to be able to get rid of the knock is to set his timing to 4 deg after. Thats right After!!! it is losing a lot of power. Anybody know what the problem could be. Can A knock sensor go bad like that?
Thanx

 

Oh yea its a 91 GTA 305 almost stock
with Brand new plugs and wires
the mixture looks pretty good too
Hangs right around 128

 

You can test the knock sensor, first i would ohm it, should be putting out something lik 3.9k or around 3.3k ohms, that is UNHOOKED also. Another thing you couple do would be to make sure its getting 5v's, turn the ignition on and probe the wire going to it to make sure the 5v's is there. I'm assuming there isn't any audible knock also. One thing you could also try(thank Glenn for this one). You could try a 3.9k resistor inline with the knock sensor and see if the knock code goes away?
But i would do the first things as suggested.

Brendan

------------------
1987 IROC-Z L98,SuperRam,EB 6085's,LPE 219/219 Roller, Crane 1.6RR, EB TPI Base, 58mm TB, ADS 24#, AFPR, K&N, EB TES, Catco Cat, 3" Borla Cat-Back, Accel cap,rotor,distro/other crap, MSD 6AL, MSD Blaster 3, Aluminum DS, 94 Disk Rear, Adjustable Valve, Precision 3.73 Gears, Sub-Frame Connectors, Hotchkis Lower Control Arms, KYB Shocks/Struts, Suspension Techniques Lowering Springs, Polyurethan Bushings all over the place, Moog Upper/Lower Ball joints and Tie Rods ends/Idler Arm,

To see the ROC, Check out the webpage Here

 

Nope no audible knock
Ill check the voltage and the ohms to see if they are all ok then ill try the 3.9k resistor
how much will this desensitise the knock sensor.
should i start at less like 2 k and make my way up? This engine wont be under my constant supervision and i dont want my friend to mess up his block.

 

This is a rough check but it works. Put the front end up on jackstands. Start the engine and apply the parking brake. Crawl under the car and with a wrench, firmly tap the block around the KS. If the engine studders and idles funny then it is prolly working ok.

Now that i think about it you are having problems with it being too sensitive. So this method prolly won't tell you anything. How is the torque on the KS. Are you running any kind of elbows or fittings. Also what mixture of Coolant are you running? That could play a role in the sensitivity or your KS.

-Lars

 

I am running about 1coolant to 3 water
Is there any Praticular reason behind puting the 3.9 resister in there or did 3.9 just sound like a good number. I mean can i just put a smaller resister in there and work my way up until false knock goes away.

 

3.9 is what the knock sensor reads with no knock. So putting that resistor in and grounding it would make the ecm think there is no knock. I dont know how using this would help you, other than testing the knock circuit and esc module to see if they are good.

------------------
87z 383,afr 190's, comp hyd roller(242/248-.540/.562,114 sep),Ported and polished mini ram, 30lb inj, 3.42 gears, tremec 5spd, , 1,3/4" slp headers, speed pro bank to bank-wb02.
"Just remember children, no man can beat you once youv'e found the cliterous." 'chef'

 

I'm interested in trying the resistor fix to cure false knock.

Could you give me some more details on how to install the resistor; which wire to use, etc.

Thanks,

Jake

------------------
1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

 

Does this have anything to do with PROM programming?

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

I agree with Tim, if you are just going to "hay wire" the knock sensor, then this really has nothing to do with eprom burning.

But, as I said, "desensitizing" the knock sensor is just "hay wiring". You have absolutely NO REASON to do something like that if you are controlling the knock sensor within the eprom. All you do is set the maximum retard vs. RPM (or MAP) to 0* and you'll accomplish the same thing, except the eprom is cleaner and quicker.

But I don't agree with setting it to "0" either. If you are sure that your engine is in perfect "mechanical condition", then controlling the knock sensor via the Attack Rate, Decay Rate and capping the maximums is a much preferable method than "wrapping some teflon tape or putting a resistor in its place". You may as well NOT have a knock sensor then...which IS THERE for a purpose.

Therefore, CONTROL it better, don't disable it or "neuter" it.

 

I have a similar problem, my '89 GTA seems to run fine, but when I put a paxton on it, it ran only a little bit faster. I figured it was a fuel problem (which was _a_ problem), so I bought an inline pump and larger injectors. After I got the fuel stuff, as soon as I hooked up a scanner to it, I found that I was getting large ammounts of knock. I took off the S/C and still got a lot of knock (according to scanner). It runs fine, it just ran a 14.7 w/ the knocking and timing retard (normally aspirated), so I think it might not be knocking. I don't want to simply "disable" the knock sensor out of fear I might have mechanical engine damage, but I would like to also know if it's false knock.

Is there any way to positively check if the sensor works or not? Does anyone have a 305 sensor that they changed out of their 350 that they could send me for a few bucks so I could compare it to mine?

Thanks.

 

If it appears to be knocking for no reason & you are not hearing it, I think that the resistor TEST is a good one. that will tell you (via your ears) if it is really knocking or not. if you dont hear anything, or it is only way up @ the top of the RPM band or something intermittant, change the knock sensore. I can not imagine that they dont go bad. I have not bought one recently, but I cant imagine that they are that expensive, as a shotgun test.

I do agree with Glenn though, fix it dont eliminate it.

BW

------------------
Bobalos
aka Bob W.
www.r71camaro.homestead.com
r71chevy@earthlink.net
<><