Scan tool vs. Casper's k. gauge

[Carolinaturbot6]

Could someone just verify something for me please. My OTC4000 has been showing me up to 10 degrees of kr while the recently installed Caspers knock gauge shows zilch. I sent the gauge back because after testing it, I assumed the gauge was bad. A new one was sent to me. I hooked the new gauge up, & I've got the same problem. I spent today making sure I had run the wires correctly & such. I have power to the gauge via the green power light comes on with the key on. I touched the power wire connection & the sender connection (yellow/black stripe) with a safety clip like instructed to test the gauge. Key was on. I even tried it with the car running at idle. The gauge lights should light up while doing this. Still nothing. I checked my connection at the ecm, & it is correct. Now, seeing how my OTC is hooked up to the diagnostic connection under the dash & my gauge is ran straight to the knock sensor signal wire (yellow/black stripe), is there ANY way my OTC can be detecting this much knock & the gauge detects none? Can the gauge somehow differentiate between REAL knock & False knock. I tested the gauge how Caspers instructed. I would really appreciate some help on this. Thanks.

[TurboDave]

Not sure how the sensativity on the caspers gauges are set up, but I can tell you one thing, in a side by side comparison, it's been shown that the OTC's will display almost twice as much knock retard as any other scan tool (Scanmaster, Direct Scan, TurboLink).

[b4black]

I posted almost the exact same question in the General Tech forum yesterday.

http://www.turbobuick.com/forums/sho...threadid=11537

I have an OTC 2000 and Casper's Audible Knock Indicator. I am seeing up to 14° on the OTC, all occuring at shifts. The Knock Indicator never goes off while driving.

I thought maybe it had something to do with the OTC going thru the ALDL which updates slowly, while other tools connect directly to the ECM for real time data. (The Gauge/Audible would be real time since are connected befoer the ECM.) But someone mentioned the ScanMaster goes thru the ALDL as well, so I guess this isn't it.

Thanks Dave, it's good to know the OTC's are reading differently than others.

[Carolinaturbot6]

I just now spoke to the GSCA the scan tool comparison deal. Naturally, they had never heard of the OTC's showing twice the knock retard as other scan tools. Maybe there is a little bias there, maybe not. I do appreciate your input Dave, & I tend to agree with you because this is not the first time I've heard that. Even if that is the case, it still doesn't explain why the knock gauge shows absolutely zero knock & the OTC shows 10 degrees. They are both reading off of the ecm, even though the gauge, as Rich mentioned, is spliced directly to the sender wire. I suppose the only way to check this thing out further, is to try & borrow TurboLink from a local buddy & compare the findings. If & when I get this done, I will post what I found. Thanks for the help guys.

[Carolinaturbot6]

Rich, I would still be careful in my tuning if I were you. I just cannot believe that even though you see no lighting up on your knock gauge & the OTC sees 14 degrees, that everything is ok. If possible, you may want to try & borrow a different scan tool & see what happens. I hope everything turns out well for both of us. Good luck bud.