Knock sensor curcuit help

[wheming]

Trying to troubleshoot/verify everything is working properly.

Background: recent work at SloweSpeed included fabbing a turbo support bracket for use with the TU header.
On some datalogs, it seemed odd that most of the time the knock voltage was 0 and sometimes only 0.2
I have this from the diagnostic manual

Step one has you check knock voltage with drbii and i get some values bouncing around, but not over 0.5v.
But where it has you disconnect at the 2way connector, there is only one wire in there, so where do you attach the jumper?
I did skip some steps and check from the 1wire connector at sensor to the #2 at the 60way and got continuity.
The flowcharts get confusing when you skip steps, or the car doesn't match what the procedure has.

[cordes]

It's just one wire. Your picture isn't big enough for me to read so I can't make much of it. If you have a scanner, why not just rap on the intake with a wrench or something and see if it produces a reading?

[wheming]

I did try that, and i didn't produce the results i expected. I taped on the fuel rail mounting bolt on the lower intake. I didn't get any different indication than just letting it bounce around at idle.
I uploaded a video, but still waiting for it to process. It should be public on my page.
Will post link in a minute.

Here's the .pdf
https://drive.google.com/file/d/0B5l...p=docslist_api

[cordes]

I really don't know why you'd put a jumper there. This is interesting.

[mopar-tech]

One tap won't do it Wayne.

Try bring the car up to a fast idle and rapping several times on the intake. I'll use a socket extension so I can strike the area next to the sensor. It takes several taps in rapid succession to get the sensor jumping.

[wheming]

https://youtu.be/dqrOYuVd-80
Video of DRBII sensor readings.
I think you can hear me tapping on the intake, but as Gary said might not have been fast enough.
Should be live in a few minutes.

A datalog shouldn't show 0v for most of a WOT pull, i wouldn't think. That is why i just wanted to verify everything was working. Maybe my MPScan is having some issues reading the sensor. I may have to try checking while driving with the drb attached.

[mopar-tech]

I'll do a video for you and others for what to look for tomorrow Wayne.

Gary

[wheming]

I'll do a video for you and others for what to look for tomorrow Wayne.

Gary

Thanks Gary.
I just have heightened my sensitivity over the years, to protect serious investment!

[mopar-tech]

https://youtu.be/0D8uz7c26bo

Here you go Wayne-

[wheming]

Thanks Gary.
Of course, it just started raining here. I didn't tap quite that quickly, so i will try that.

[wheming]

https://youtu.be/0D8uz7c26bo

Here you go Wayne-

Just tested. Looks to be responding similarly to your video.
I'm guessing you have to time the simulated knock just correctly in order for it to read a voltage? Only in a proper firing or prefiring spark event?

[mopar-tech]

No timing, just start banging away and I assume at some point the blows just happen to fall on a firing event.

[wheming]

Yes, that's what i was meaning. It would explain why with just the key on and scanner attached i saw no voltage changes when tapping. And also when the car was running with the scanner attached why i saw no voltage spikes when i just single tapped and watched scanner.

This result indicates the sensor is ok. It is a new mopar one installed last year during the engine rebuild.
I need to perform a road test with the drb attached to verify readings. It seemed odd to record mostly 0 - 0.2v on the sensor during a mpscan datalog, especially when datalogs before would indicate higher readings (even though less than knock threshold).

I want to do these doublechecks before i increase timing, or increase boost testing. But, if everything looks good, then i can safely bump up my timing. I know i'm well in the safe zone right now, so there should be plenty of room to improve performance.