Okay, from the datalogging Ive done, its been determined I have lots of Knock retard.

Things I have done:

I just re-adjusted my RR
I bought an LT4 Knock sensor, not module. I have not installed it yet, I cant think of a good way to get to it! Its buried pretty deep in there, and it looks like it may come out in pieces. Any tips?

I wanted the 96 sensor hoping that it is a little less sensitive since they came with RR, and I will use some teflon tape and torque it only to 12-13 lbs.

I was also told to check the headers and ypipe for contact on the frame, motor mounts, and heat shields. Low and behold, yes, the clearances are all so close, that I am almost certain they can touch during WOT.

What methods have you guys used to bend, beat, or make clearance?

THis Knock retard is a tough gremlin!! :smash: :banghead:

Thanks!

 

Sure it's not real knock??? I'd try some 100 octane first to rule it out....
As for clearance...a big pry bar!
Another trick I've heard of to decrease knock sensor sensitivity is to put an elbow fitting between the sensor and block-never tried that myself but may be worth a try.

 

Indeed you might see if you have real knock:
-back off on base timing
-higher octane fuel

 

You didn't mention if the knock happened at WOT or not.
If your knock isn't when you have the throttle mashed, you may have a carbon tracked Opti-Spark. However, I'd expect that you would have what seemed like a miss too.
When my Opti-Spark carbon tracked, it allowed the next cylinder in the firing order to fire prematurely, and this caused extreme knock retard at about 10% throttle.

Tom Piper

 

No opti on my 91
The timing is dead on at 6, and Im using Mobil or Amoco Super
Its al at Mid-WOT

Elbow trick sounds cool.....I need somebody to second the motion!

 

When I saw the "LT4 knock module" reference, I assumed we were talking about an LT1/LT4.

Tom Piper

 

So tonight I am going to try to change the sensor.... any tips, anyone, anyone???

I have a feeling it wont come out in one piece. :smash:

 

Strap wrench. I use one on my sensors when I drain the coolant.
Comes off no problem. Good Luck. :seeya

 

Gus,
If you have knock, chances are its just the sensor, unless you have machanical problems with the car. Best way is from under the car, its real easy that way. Get the other sensor ready while you unscrew the old one, and you don't loose too much coolent if you fast about getting the new one it.

By the way, the LT4 modual is what determines how sensitive to read the inputs from the knoc sensor. The sensor acuracy is the same if not more sensative. The modual does the translatting to tell the ECM what to pay attention to.

On my L98, I had a doudle roller timing set (real noisy) and RR's (clak clak clak), no problems with knock or timing retard while data logging, so like i said most likely its just the sensor. Also make sure you unplug the Electronic Spark Control wire (tan wire at booster), other wise timing will be off. Car should be at opperating temp, in drive, and wire disconnected to get an accurate timing setting.

Good Luck,
Victor

 

As for removing it, I just use what ever size wrench fits on it. Havent broke one yet.

I Have heard about the elbow being used on the sensor, it was sone to a blown, roller rocker car with hearders to kill off false knock he was getting.

I tried the teflon tape on my sensor and I got a code that the sensor was not working because it was not grounded to the block. I removed it and installed it normally.

what I later did, I wired in a switch to shut down the knock sensor to test things, I had to use a resistor to trick the computer. I dont remember the value on the resistor off hand.

 

Okay, got in there tonight when I was doing the Torque converter..... the old knock sensor was BROKEN!! The center section was just wobbling loose in the case. Must have happened during one of the many header installs.

We took it out with a vise grip. I got the LT4 sensor in and connected. I also found an old header bolt rattling around in the collectors, it must have fallen from the top, and got caught in between the collector pipes. IT WAS A ROYAL BEETCH TO GET OUT OF THERE!!!

We tweaked and bent, and banged on the headers. I think have them all clear of most every obstruction. I feel much less vibration when driving now.

Also found the rear c-beam bolts were a little loose, it was the source of the noise I was getting from the rear end.

I hope to get it on the scanner tomorrow to see if the knock retard is gone.

As far as the Torque converter install......without a lift, dont even try it!!!

It runs really different now, got to get used to it.

 

Gus,
Do a search of the past year on how reduce the KS sensitivity, it worked for me.
BTW, you're right a TC change is easier with a lift, but I've done a couple in the driveway with a floor jack & jack stands.

Good luck, Dave

 

Gus,

You should be fine with the stock sensor and module. You just have to as I mentioned in my email a while back, eliminate any and all sources of rattles that could be causing false knock. You have eliminated one of the sources that may people overlook, and that is the TC. Believe it or not they can cause false knock as well. When you sent me that log of your car, I knew instantly that there was no way you were getting that much knock with that timing that I gave you. Just keep plugging away. One item at a time. Sometimes as you found, it not that obvious what the problem is, like the bolt caught in the header :crazy:

Looks like you making good progress. Don't be afraid to bang around under there to find other sources of loose items.
:cheers: :cheers:

 

Jesse,

I may go back to the stock sensor. I got a code, but I also had a loose plug wire. I will reset the system and watch for another code, if I get one, I will swap the sensor back to the L-98 one.

As far as the broken knock sensor that was on there.......that most likely was the source for the knock, I HOPE! the other items are not so near that they would be so easily picked up. The TC that was on there B4 was bought from a cheapy autoparts or rebuilt I guess and replaced when the tranny went bad last year. I had no clue what a good TC was worth back then so I never gave it a thought.

I think the only thing left is to replace the motor mounts. The one on the passenger side had very little clearance, not much left on that baby. I did notice that they are a real BEETCH to get to though. I may not do that for a while.

More data to be collected this weekend, I hope for better results. I will let you know.

Everything does seem a bit smoother now though.

I WOULD NEVER TRY A TC IN THE DRIVEWAY!!!!! NO WAY!!!! You are da man!!! Looks like a good way to turn a 3 hour job into a 12 hour job!

 

Gus, are you saying you do not have a cover over your knock sensor?

I have one that bolts to the oil pan bolts. it is kind of shaped like a sheet metal T.P.

 

My knock sensor was wounded....it has a stamped case. It looks like during one of the many header installs it was damaged or something. The center piece of the casing was barely held in place, it was just dangling and mostly held on by the harness. I replaced it.

 

:lurk:

Just making sure no one in here is condoning violence toward the mentally challenged. :skep: :D

 

I did that as well, by changing the knock sensor i got a check engine code, as well as black smoke after start up, car sounded very smooth idling surprisingly, changing the module is the way to go.

 

I get a code because I forgot to switch the wires on the connector I guess! I hooked it to the laptop and I was getting 6 solid degrees of spark retard at idle. I disconnected the sensor and it was the same. Also kept throwing the code 43. I dont feel like switching around the connections in such tight spaces or making it more difficult for the next guy if I ever sell it so I will buy a new 91 knock sensor and install it tomorrow. If the car still runs good with 6- 15 degrees KR, I can imagine what it will do when its right.

 

Okay, I got the right sensor back on, a new one. It now doesnt give me a code, and seems to work right. I still get about 6-9 degrees of spark retard under heavy acceleration. I get about 3 knocks on a run. This is driving me nuts. I would like to know how much you guys are getting on your runs.