DelSoto

Replaced it. Checked the wiring. I even tapped on the block with a small hammer to see if it would 'read' that and it does.

95Blackhawk

I have not heard that you confirmed this is true predenotation. Have you increased the octane levels of your gas (example: add xylene in proper proportions) or pulled timing across the board and recheck? You need to confirm it is real knock first.

DelSoto

I had Bryan pull timing. Haven't got a chance to put race fuel in it yet.

JP95ZM6

I was trying to figure out how to test that thing. Hammer. So simple. Should have been obvious I suppose, but I still got that 'Ah Haaaaa' feeling...Made me feel kind of stupid for not thinking of the obvious. Thats the beauty of it. I was thinking DVM, oscilloscope. Funny, like a bunch of scientists standing around scratching their heads trying to figure out why their super-contraption won't work, and the lab idiot walks up and plugs it in.

Now I think I'll go bang on my TV for a while to improve the picture.

DelSoto

Uhh ....was that a compliment or an insult?

97bowtie

Get the car scanned. You are stabbing in the dark at this point.

DelSoto

have....wanna see the log?

edit: DataMaster of it running badly

JP95ZM6

Oh, definately a compliment.

DelSoto

I thought it might be a dumb thing to do but made sense to me

Can anyone take a look at my Datamaster log and see what I might be having prob with?

stephenspann27

may car pulls 15 degress of timing at WOT
It runs really well considering. I have headers, and some valve train noise is the only reason I can think of why it's hearing knock. My knock count does correlate to the timing that is pulled. I did the "free mod" that desensitized the knock sensor in which you place a resistor inline with the KS. That had little effect....I am considering programing out my KM and KS. I"ve heard of a few ppl doing this without having problems

Injuneer

Are you sure the "knock" you're hearing isn't piston slap or a rod knock?

There is no direct correlation between knock count and knock sensor activity. It is entirely possible for the PCM to retard timing in response to the knock sensor signal, without an increase in knock count. It is possible for the PCM to retard timing based only on the knock count. Appears some "count" may be generated by the PCM's evaluation of the engine operating conditions.

And to make sure I understand what you said, when you tapped on the side of the block near the knock sensor, the data log/scanner indicated that there was actual knock retard being applied?

Have you pulled the knock sensor to insure the end of it isn't plugged up by something.... e.g. a piece of RTV..... preventing it from "hearing" pre-ignition or detenation?

Your data log appears to be 2.5 minutes of idle, with a few blips of the throttle. Not sure what a log that limited is going to show, but I'll look at it.

DelSoto

Thank you Fred.....I greatly aprreciate you looking at it.

I have another log of a few miles of driving with mormal cruising speeds and some WOT but it seemed silly to post that because the car was running very well (minus some detonation). As I mentioned in some other posts this is a heat problem. Something on my car does not like to get hot. For the first 5-10 miles of driving it is fine. Also while it is as cold as it is outside it is very difficult to reproduce the problem. But it will happen if the car gets warm enough. The only reason why this log is so short is that the car is basically undrivable in this condition. It will barely move under it's own power. Here is the log of the car running fine including the 'hammer tap' at the end where I got pissed off that it never reads/retards the timing even though I can hear some detonation at lower rpms (3000-4000 rpms)

Datalog

CamaroUK

My brother had this kind of problem with his '94 LT1 Corvette.

The engine would run fine until it reached its normal operating temperature, then it started detonating under load/acceleration. (sounded like shaking up a can of spray paint).

It would misfire quite badly when revved also.

After hours of checking all the plugs and swapping over plug leads to track down which cylinder was missing, it started to get dark. Thats when the problem became aparent. Upon each series of misfiring we could see the spark arcing from the HT connection at the opti to the block, the plug boot also appeared to glow as well.

We guessed the opti was'nt transmitting spark so changed out the cap and rotor for an msd unit (The old one did show corrosion on the points, some worse than others), the problem went for about 3 months but then it came back, although admittedly nowhere near as bad, as the engine had to get really hot before it started knocking. However the misfire was cured

The problem was lessened further still by using super unleaded.

The car has since been sold, so we never got a chance to find out for sure what the problem was, but to be honest, we were out of ideas.

Something else for you to check for!

stephenspann27

I'm not sure about camaros in the UK but the ones made for the US are designed to run only on super unleaded....

Injuneer

They are designed to run on 91 octane unleaded fuel at sea level (and lesser octane at higher elevations). And the knock retard system and "low octane fuel" programming in the PCM allows them to be operated on fuel with an (R+M)/2 octane rating of 87 with no engine damage, just a loss of performance.

I don't think octane is the issue. It appears the problem is he hears what he thinks is detonation, and the knock sensor isn't responding.