Knock Sensor Resistance
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Pro
Joined: Jul 1999
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From: Eagle IDAHO
Cruise-In I Veteran
Cruise-In II Veteran
Knock Sensor Resistance
My knock sensor is new, and reads 300 K Ohms on a good quality DVM. Anyone know if that is normal for an 85 Knock Sensor?
I'm having all kinds of timing problems and am looking at all related possibilities. This condition has existed since the engine rebuild.
[Modified by NHVett, 7:50 AM 8/4/2001]
I'm having all kinds of timing problems and am looking at all related possibilities. This condition has existed since the engine rebuild.
[Modified by NHVett, 7:50 AM 8/4/2001]
Advanced
Joined: Jul 2001
Posts: 70
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From: lakeville, ny usa
Re: Knocking at Sensor's Door (NHVett)
the sensor is probably way to tight ......sensor should read 9.5 to 10 vcolts @ no detonation, less than 1 volt means it is sensing detonation, or is damaged
Team Owner
Joined: Mar 1999
Posts: 22,025
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From: At the beach in little Rhody
Re: Knock Sensor Resistance (NHVett)
Don't know about 85, but a 90 should read 3,300 to 4,500 ohms from sensor terminal to ground. I imagine 85 would be of similar values such that 300 ohm may be indicating a problem. I would remove and check resistance between pin and housing. If still 300, you may have damaged it during installation.
Burning Brakes
Joined: Jun 2000
Posts: 865
Likes: 6
From: Auburn Michigan
Re: Knock Sensor Resistance (NHVett)
I printed out a thread from over ago (Just found it) that recommended a 4.5k to 5k ohm 1/4 watt resistor to bypass the knock sensor on an 85. I just got back from Radio Shack with a pack of 4.7k ohm resistors, soldered a couple leads to one and "replaced" my knock sensor with it. I just got done with an engine swap in my 85, and I think I may have whacked the side of the sensor when I was lowering the motor into it's mounts, and was unsure of it's operation. I just got back from a quick ride and it seems to be crisper (if you know what I mean). No check engine light. I got on it a couple times after I got all the fluids warm and I didn't hear any spark knock either. I had a 68 camaro with 10.5/1 ratio, so I know what spark knock is. Will play with the Gtech tomorrow....wife getting a little annoyed......
Later,
Carl :yesnod:
Later,
Carl :yesnod:
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From: Stay dangerous my friends
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I just measured a new knock sensor on my '86 C4 and it's 99.9klohms. FYI, when it started pinging, it turned out to be a blown head gasket. I found it using the radiator fume testing method. Good luck.
Tech Contributor
Joined: Jun 2004
Posts: 20,905
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
FWIW, the harness connector (on several model years) was made with some soft conductive metal coating to conform to the sensor terminal for a good low-resistance connection to the sensor. The downside of this is that the harness connector has a limited ability to survive much much more than a handful of connections and disconnections. If your connector has intermittent continuity, that can make the ESC module think that there is knock going on when there actually isn't any.
Keep us updated on what you find out.
