"flat response" knock sensors

[NSFW]

It's a fun car, but the project has been a pain in the ass.

[V8fan]

It's a fun pain in the ass.

Shortened a bit )
The longer u build the more u doubted about previous decisions
Now Im cut off my welding cuz I found better solution )

[NSFW]

100% accurate. Looking forward to getting it on track soon though.

[cwalsh]

100% accurate. Looking forward to getting it on track soon though.

Did you have time to get it to the track? Were you happy with it?

Chris

[NSFW]

Yes and no... Got two track days. The first was in pretty heavy rain, so I couldn't use much throttle, but everything went well. The second track day was dry, but I had to get towed off after just a half a lap due to a DBW TPS code putting the car into limp mode. I was stuck at the bottom of a very mild hill, and it wouldn't even climb it in first gear. Back in the pits, turning the car off and back on made the code go away and give me throttle control again (should have tried it while I was waiting for the two truck!) and I couldn't get the problem to come back despite trying, so I did three track sessions. Everything went fine, but the DBW thing still worried me so I drove home rather than doing the last session.

Talked about the code in a C5 group on FB a couple days later, and one guy there seemed completely certain that the code was due to a bad 6-pin DBW connector on the engine harness, so I replaced it.

When I was troubleshooting at the track I moved the DBW wires around, and just putting a slightly different bend into the wires might be what "fixed" the problem for the rest of the day. It didn't come back, even after the 90 minute drive home. So hopefully the new connector fixes it for real, but we'll see.

The track sessions were fun. I'm pretty rusty after a few years away, but I kept all the tires on the tarmac and was only 2-3 seconds off my best times by the end of the last session.

In other news, at the last dyno session it was losing fuel pressure up top, so the throttle curve tapers off above 5000 RPM... While replacing a rubber hose with a fancy braided hose under the hood a couple weeks ago I noticed that the fuel left black stains on the rag that I used to catch the fuel that poured out of the rails. So I have theory that the pressure loss might be due to a clogged fuel filter. Not sure what the black stuff is, but I wonder if there's an o-ring decomposing in the fuel tank or something like that. I have a new filter ready to go on soon.

Getting back to the thread topic...

I am pretty sure I figured out the issue with the knock sensors not working - there's a noise-floor parameter that's got a 0.5v minimum in the stock tune, and the signal from the sensors mostly hovers around 0.1 - 0.15 volts. so I lowered the floor to 0.3, but haven't had a chance to verify that knock retard is working yet. I literally figured that out the night before the 2nd track day, but had too much on my mind to do any data logging at the track.

Last but not least, I thought the engine sounded extra clicky when I was next to the pit wall before a track session. And last weekend I could hear clicky/tappy noises inside the car while I was on a short test drive after changing the DBW connector. It's not terrible, but there's something going on.... I'm hoping it's just a bad lifter but I dunno. Never a dull moment with this thing. It's cursed. Going to take it to a shop soon to get the noise investigated, and to get the fuel filter replaced.

[NSFW]

I switched from track wheel/tires to all-seasons last weekend and the engine sounded completely normal. I might be a little too paranoid. But I also found a nail in one of the all-seasons, so no driving (and no knock sensor troubleshooting) until I get that fixed. It's at a tire shop now.

[cwalsh]

I know its been a while but with spring coming and cars getting out this subject comes to mind. Has anyone else played with any of this? NSFW how is you Vette doing? You thought you heard some extra clicky noises, is it all good?

Chris

[G-Body]

Wiring:
Bank 1 ground: J1, pin 49
Bank 1 signal: J1, pin 09

Bank 2 ground: J1, pin 50
Bank 2 signal: J1, pin 10

I`m not sure where you dug up the bank 2 inputs, but thank you! That crossed 2 more pins off my P59 list that I could not figure out what they were used for.

[NSFW]

It's been one thing after another with my car. I think I found the last little detail for getting the knock sensors to work - there's a "noise floor" threshold in the tune which is 255mv in the stock tune. Looking at the value in the logger, the threshold needs to be much lower, and I was going to try 110mv...

But the aforementioned clicky noises stemmed* from intake valves whose lash caps came off. While the heads were off, the combustion chambers were CC'd and as my tuner suspected the compression ratio is too high. Golen is setting everything right but he's been waiting on head castings. They were supposed to arrive last week, so I need to check in...

* That was a pun.

[Phoenix]

It's been one thing after another with my car. I think I found the last little detail for getting the knock sensors to work - there's a "noise floor" threshold in the tune which is 255mv in the stock tune. Looking at the value in the logger, the threshold needs to be much lower, and I was going to try 110mv...

But the aforementioned clicky noises stemmed* from intake valves whose lash caps came off. While the heads were off, the combustion chambers were CC'd and as my tuner suspected the compression ratio is too high. Golen is setting everything right but he's been waiting on head castings. They were supposed to arrive last week, so I need to check in...

* That was a pun.

Are you talking about the B6240 - Knock Sensor Initial Threshold parameter?