You and I have similar situations as far as having mystery knock. Driving around I get huge knock counts and sometimes out of the blue I'll get knock retard as high as 6* or even 10* at WOT. Been like this since I got the engine and I've never figured it out. My tuner agrees that there HAS to be noise coming from somewhere but it must be internal because everything looks great on the outside.

Tried both LT1 and LT4 knock modules, torquing the knock sensor to 12 ft lbs instead of 14, did all the voltage checks. Ran with different tunes from my tuner and PCMforless. There's no power loss that I can feel and no drivability issues though. And my knock is very sporadic and random, yours seems to be consistent.

Hope you get this figured out.

 

Im looking around. Gonna check this out today. It looks like it maybe makes contact when i rev.

Its a header tube and motor mount clamshell on passenger side. Gonna see if i can see it hit or something idk.

 

Just checked that mount and tube out. It's not hitting.

Could it be the passenger Heatshield directly ontop of my header? It's vibrating on top of my header and if I push up on it, it stops.

 

Didnt bother to mess with the heatshield since I dont have my laptop right now to scan the knock.

But i tried swapping in some parts from my GFs car to try and fix my intake backfire. Put on her stock ICM and went for a test, still revved up un even and got some intake backfires.

I put on her MAF and elbow and that actually seemed to help alot. It revved alot alot smoother. Car didnt shake from 1-2k as it revved up. and I only got maybe 1-2 backfires instead of a bunch. I went and punched it for a stop about 10 times with her MAF and I didnt get any single backfires like it did before. It just revved up smooth and took off (kind of, just sat there spinning)

Left pic is my MAF and the right pic is her MAF...

It looks like one of my strings is broke, could that make a difference??

 

So I unplugged my o2 sensors and drove for about 20mins... And the
Car drove absolutely perfect. All casual driving problems were gone. What's the cause of this??? Need new o2 sensors? That sucks because they are fairly new.

 

Went out with the o2 sensors plugged back in and the MAF unplugged. Still drove
Pretty crappy.

So best results was with only the o2's unplugged

Someone let me know what's up!

 

The o2 are for fueling corrections so a few things come to mind- they could be bad, you could have an exhaust leak infront of them(even vacuum or unmetered air leak). Misfires could be why it runs better with them unplugged and perhaps the most logical. Might be time to look at plugs and wires and take a look in the dark for arcing(some water from a spray bottle may help the arcing). Pay good attention at the boots and near any metal surface its touching or near especially headers(manifold).


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What brand are the "fairly new" O2 sensors?

 

AC delco. Maybe 6months old.

I put them in with my long tube install. I know that some new headers foul them out. But I put them in when I starter it because my headers were used. The person before me painted them kind of ****ty so maybe some paint was on the inside? Idk

About to have a real tuner look at my car soon.

 

Might be worth looking at passenger side o2 sensor wiring as it gets pretty close to header and you may have burned it. I am not sure if you can unhook only one and have the other still make fuel corrections on its bank. I bet Fred does though. Did you ever look at the fuel trims when you were scanning data or look at o2 volts?


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I'll look at the wiring today I see if there are any burns.

I didn't look at any thing when I scanned it because I don't know what I'm reading most of the time. I just know that knock count is not wanted.

I shall have a real tuner look at it soon. There is a guy in my group that tunes LS1s in DFW and just got all the software and cables for 94-95 obd1 f bodies for tuning.

 

Finally got a tuner to look at it! Think we found the problem. The mail order tune was not do bueno. I had a 14.0/1 airfuel ratio... That's probably the cause of my backfire. Bit he fixed a lot of stuff. The car drives a 100x smoother just cruising. No more hesitation stuttering and stuff. He fixed my timing some ad we disabled my knock sensor. I was indeed getting false knock. Powerband is a lot smoother and my shifts points are better. He is gonna tweak it more for me on the dyno later.

Anyway if you're an LT1 in DFW TX check out (lttuner.com) he is going to begin tuning LT1s