97 Skylark Knock at high speed - HELP

Hello and I am wondering if you can help me with my problem:

I have a 97 skylark custom that had a remanufactured engine placed in the car, and now (about 1000 miles later) it seems to retard timing due to knock at high speeds. I don't hear a knock but the timing will retard 20 degrees. If you immediately release and press the accelerator, the problem disappears. The problem appears as you drive the car (when you first start, it doesn't have the problem, it appears after a few minutes and gets worse the longer you run the car)

I have access to sophisticated scanner equipment because I work for a scanner manufacturer, and I develop engine scanners for a living.

I have had 3 ASE mechanics look at the car and we have replaced/checked the following things

O2 sensor - replaced.
Fuel pressure - checked, did not drop during problem.
Vaccum pressure - fine. I did not sense and drop to indicate a blocked exhaust
Knock sensor - replaced.
We did a standing test of the ignition system - seemed fine.
Performed CKP learn procedure (new engine). This didn't help.
Checked TPS - no problem there.

Any ideas? Ignition module?

Thanks
Jim

Do you have reman specs? If a cylinder is bored 0.030" or more, the overall casting can be altered enough in the process to affect the amplitude of the detonation sensor output. If this were an older (separate ESC module) installation I'd suggest bypassing the ESC system and manually advancing base timing to compensate. Since you're dealing with OBD-II, you may have to try to attenuate the KS signal with a resistance installed in parallel with the sensor output. IIRC, the appropriate value for that vintage PCM would be around 220K to effectively shunt the lower level signals and still allow the sensor to respord to test knocks. Since you presumably have the resources, check a STOCK KS output versus your KS output with a storage scope. Review and compare the amplitudes, and see if I'm way off base (again). Or, you could simply clip in a resistance and try it.

Good idea. I'm sure it was bored more being a reman. I did a little playing around this weekend and picked up a new knock sensor, and with my modis scanner (I work for Snap-on BTW) from work, I did a CKP learn (Crankcase sensor learn). I also discovered a loose wire on one of the coil packs, it was not connected correctly. The problem is much better, but now, when I accelerate downhill, the knock retard kicks in! haha. Not when accelerating uphill anymore. Strange! Some of the ASE's we have working for us suggested hooking up a scope to the knock sensor, but I don't know what to look for.

The reman engine makes a little lifter noise, and someone suggested to me that the lifter noise may cause the knock retard.

I also ran the car with the Knock sensor disconnected, but the ECM backed up the timing. I didn't hear any knocks or pinging though but of course its kind of hard to hear really.
Also, when going 65+ MPH, the "KS Noise" is pegged at +5V. I don't know what normal is in that case. Any ideas?

I'll try to attenuate the sensor with a resistor. Thanks for the suggestion!

Jim