Heavy spark knock and knock retard just started, Possible causes?

Ok this is more of a thinking out loud question or post, and I am looking for some thoughts or feedback.

The Facts: 1995 K2500, 350 roller, Dart Iron Heads (2.02 x 180 cc runner x 64cc chambers), 96 Vette Cam installed 4 deg advance. (201 in dur/208 ex dur@.050, .477 in lift (1.6 rocker) / .459 ex lift (1.5 rocker), 117 overlap), Stock TBI intake (Bored) EGR removed, Bored TBI (SPR performance) with Cop Injectors, 18 PSI fuel Pressure. 1 5/8 shorty headers, 3" y pipe into High Flow Cat, and 3" all the way to the back, stock trans and convertor. Compression is 9.1 static.

I just got this installed and running. I have driven it 300 mile plus, I finally got my burner and was able to edit the BIN file to record wide band data.

I updated the BIN and went out for a drive and to record wideband info, on this drive I started getting heavy spark knock and knock retard, to where the truck is stumbling bad. It seems to act up when I am trying to get close to 30% TPS, If I stay below 30% I can nurse it around. I was trying to get a data log in as main TPS positions possible.

Now on the 300 miles of driving, I had no issues, the AFR gauge was showing some lean spots but no real knocks recorded. The bulk of the miles were hi-way.

The only things that changed was the EGR info to record wideband info and the gas.

So, my current thinking is 1) I am going to check Fuel PSI again, make sure its still at 18, 2) pull plugs and have a general look at them, 3) check exhaust for possible air leaks, no indications but seeing I have 300 on it, it won't hurt, 4) drain some gas and put in 89 or 93 and see if it still knocks. I have never run anything but 87 but you never know.

Before I start making changes, I want to take small steps to make sure everything is solid.

Also some other info, all sensors are new AC delco, Dist is new GM unit (1103952), wires are new, etc.

Here is the base bin file.

Here are some data logs:
300 mile drive are:
First Drive, 2nd Drive, 3rd Drive, Drive to Nick, Drive Home. these have no wide band data

Spark Knock start drive:
Drive to Pick up Mulch and Drive home with Mulch.

Typically the 1995 4L60E will have a PWM Torque Converter.

The Base Bin Tune file does not have PWM Torque Converter Flag set.

What was the original BBC for the Base Bin Tune

The attached BJLY.bin file is for a 1995 4L60E with a PWM Torque Converter.

My stock bin or computer is the BJYL, but I do not remember what the base bin was based on.

My base bin was created by a tuner whos main focus is LT1's. I got it about 4 years ago, it has taken me that long to get time to swap the engine. In that 4 years I have been reading a lot of stuff on gearheads pages and learning.

So if the PWM is not turned on does it let the convertor just go to complete lock up?, thus putting a larger load on the engine to soon?

I will update the base bin and burn it, and to a test log/drive

Thanks for your feedback Dave

Quote:

---

Originally Posted by Sledhead2

My stock bin or computer is the BJYL, but I do not remember what the base bin was based on.

My base bin was created by a tuner whos main focus is LT1's. I got it about 4 years ago, it has taken me that long to get time to swap the engine. In that 4 years I have been reading a lot of stuff on gearheads pages and learning.

So if the PWM is not turned on does it let the convertor just go to complete lock up?, thus putting a larger load on the engine to soon?

I will update the base bin and burn it, and to a test log/drive

Thanks for your feedback Dave

---

PWM TCC is a terrible strategy, I mostly disable it as well.

Again what it the effect on or off?

does convertor go full lock up with it off?

reading on line says with it on, it slowly goes to full lock up?

Quote:

---

Originally Posted by Fast355

PWM TCC is a terrible strategy, I mostly disable it as well.

---

Everyone tunes differently.

Starting over with a stock tune, with the bare minimum of changes ( for example: fuel injector flow for 18 psi fuel pressure regulator) can solve many problems.