Is you Knock sensor taking performance down for the count?

[LGAFF]

Interesting to note that after running 12.4s @ 117.5mph and then adding a lightweight flywheel I saw a decrease in performance. I had been running 12.6s at 114.5-115 range.....I then noticed my knock sensor was unplugged, problem solved right? wrong! after plugging it in I saw no change, then last year I purchased a Tech 1.....my car was pulling 10 degrees of timing,constantly and in fact on hard acceleration I was pulling even more.....

So I went down to my local parts store and purchased a ZR-1 specific replacement...Pete had warned me to check it by OHMing the sensor and that a ZR-1 sensor should OHM at 3.0-4.0....wrong resistence; this sensor from O"Reillys tested at 99.

Then I tested the one on the spare motor, bad too..no reading

Now keep in mind my 92 has 23K miles on it....and even with the timing retard it seems very seat of the pants fast.....so how many of you weekend warriors at the strip are losing .2-.5 from timing retard.

Time to pull the Fluke meter out and check yours....oh, by the way GM discontinued the Z knock sensor....they are still availble from some vintage parts places, Jerrys, and I imagine Kurts too.

Thanks to Pete for the heads up!

[mike100]

I have not observed much pulled timing on my tech1 data. maybe a degree or two and a small ping when it is hot, but mostly it is showing the full amount of timing when I have done the recording under accel at the data rate the scanner is capable of.

The biggest question is why does it pull timing when you disconnect the sensor? Does it have to have a grounded signal to run properly?

I can't recall, does it list a timing retard number? I do know that the total timing shown is 6 degrees less because the raw value does not include the 6 degrees of lead cast into the sensor mount/crank notch.

I will check it next time I change the oil out of curiosity.

[LGAFF]

I do know that are cars with known false knock issues that use a resistor to create a false signal that the sensor is present to thus avoiding "False Knock" and avoiding timing pull from the sensor disconnect.

[LGAFF]

Early 85=89 TPI uses a 3.9K knock sensor, wonder if that would work for us?

[Pete]

If you unplug the sensor the ECM thinks the sensor is bad basicly there's no singal/voltage going to the ECM and will retard timing so you don't blow up/hurt motor.

Pete

[Paul Workman]

Tuning the knock sensor...

This may open the door to using currently available knock sensors... What say you Tuner Pro gurus?

C-link

P.

[Vettetech1]

Bring up this thread again. Got a 92 zr1 here has a code 43. Suspecting a knock sensor issue. OHMed the sensor and it is at 3.891k. Customers car not sure of full repair history on it. Know all primary and Secondary injectors have been replaced over the past 3 years, and the fuel regulator was replaced last year. Just don't seem to have the power it should. Any suggestions would be helpful as i don't see to many of these.

[LGAFF]

Is your ASR light or other lights coming on? I had a crack in the board of my chip for the knock sensor

[Pete]

Did you or somebody replace knock sensor?
You might have a 1990 knock sensor.

I will check and get back to you later.

Pete

[XfireZ51]

Have a read on this thread for some additional explanation. It's not a matter of knock, it's a matter of the knock sensor circuitry being operational. You don't get a MALF code if knock is occurring.

http://www.thirdgen.org/techboard/di...de-43-esc.html