I hooked my x-ray up to the GTA, which I presume has the stock PROM, and went for a ride. 2 miles down the road, I already had 27 knock counts. Taking off easy from a red light, 3 or 4 more piled up. I went up a steep hill and I watched the computer pull out a maximum of 13* of timing. This seems quite excessive for a car with a stock chip, but before I go adjusting my timing swapping to 92 octane, I wanted to see what everybody else thought about this.

 

I've seen this more often than I care to recall. In fact, this is generally one of the first things that blows people away when they first hook a scan tool up to their car.

What's worst, if you were to "reconcile" the effective total spark advance, don't be shocked to find out that you aren't even getting 20* of advance @ WOT (after deducting all the spark advance).

 

So what I saw was normal? My 85 didn't give me dick for information through the x-ray, and this is basically my first go-round with the 165 through the tool. Before I over reacted I wanted to find out if this many knock counts was the norm, or if what I saw was excessive.

 

I don't know if I would call it the "norm", but I don't find it unusual either. The good news is, that from tuning (and possibly some head work), it can be greatly reduced.

Just don't be shocked to find that you can't run too much spark advance @ WOT without noticing "knock retard". The next most common reaction is "denial" and belief that "these MUST be false knock counts". But, if they "disable/cap" the Knock Sensor they then find they get actual audible knock somewhere from 26-32* with stock GM heads. YMMV.

 

Glenn, my 87 behaves like this also. Like you said, I was kinda in "denial", not believing that at part throttle, such low timing could be causing detonation. If this is "normal", would I be better to pull timing out of the tuneup, or just let the sensor do it???? I am thinking the sensor may be a little overreacting. My car is running a little rich also in the areas it is getting knock, so i figured that would protect it a little, but no such luck.

 

Pull the timing. Those little "knocks" are slowly killing your engine IMO. After a LOT of testing/tuning I seldom get ANY knock counts - even on long drives. And yes, when in Highway Mode I do run some high spark advances and I can still go up some decent grades without any knock occuring. Lots of testing and work to get to that point.

For WOT, I REALLY had to pull the timing back. BUT, with a lot of playing (and controlling the spark curve), I actually have 5-6* more Total Effective Spark Advance than I did when I started. Don't let the KS "control the spark advance". It has a tendency to "overreact" at the slightest hint of knock AND when it REALLY SHOULD be doing it's job...it goes deaf, does nothing and audible detonation occurs.

Use the Knock Sensor as a "tuning aid" for you to modify the tables, but don't rely on it for the 'final tuning' - you may become sadly disappointed.

 

That is kinda what ive been tryin to do. Even if I end up with not much timing? I tried something else today. I put in 93 octane, and it still will pull out timing up a hill on the hiway with the blm's around 118-120. I think you are right, the little bugger does overreact to pretty much anything it feels like . Gotta work on the spark tables, and I was thinking about trying to limit the amount it can retard, and seeing if i get any audible knock. . I get knock counts just starting the car, and when i accelerate at all, knock counts go up. I am not using arap, btw, Im using a stock 89 iroc 350 bin. ARAP is WWWWAAAYYYY to much timing.