OK, I used to have a 305 TPI in my Z28 Camaro. I had a 355 built and installed in my car. Now i have changed the Knock sensor. I got one from gmpartsdirect.com for a 350. I am also using a 1227730 S/D now instead of a 165 MAF ecm. I was banging excessive knock counts on datamaster. Is there any difference in the 350 sensors? I have noticed that between 87 - 89 they run different numbers compaired to 90 - 92. Does it matter which one I use?

 

The 350 ESC is different from the 305 ESC. You will want to run one with the correct year you are running. Ie. 85-89 (MAF) 90-92 (SD)

The module runs $100 from a GM Dealer.

I think you can get it from one of the sponsers for like 85 + Shipping

 

I already have a 350 Sensor. But don't know what year it is. The 350 ESC isn't external and mounted on the firewall like the 305 TPI's is. I already bypassed the 305 ESC. Is there a difference between the years on the 350's Knock sensors?

 

Yes, the 350 ESC looks identical to the 305 ESC, and is mounted in exactly the same location. Atleast it is on my 88 setup. My understanding is if you have bypassed that, then thats where your knock count is coming from.

The knock sensors are different too.
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85-89 350 TPI ESC Module - 85-89 350 ESC

90-92 350 TPI Knock Sensor - 90-92 350 Knock Sensor

85-89 350 TPI Knock Sensor - 85-89 Knock Sensor

 

Going through the wiring diagrams for a 91 Speed Density system, The ESC Electronic Spark Control isn't even displayed. The ESC has been removed as the ECM controls the Spark tables. So by-passing by attaching the black wire to the white was correct. Car is still back firing only when it goes into closed loop. So that might be a clue that the program code inside the bin is bad.

Hooked up the snap-on MT2500 tonight and started it up. Sounds good at an idle. Got the engine up to around 4500 rpm and still didn't hear any problems. Once in a while if you pump the throttle it will backfire right out the TPIS intake system. It was saying that my BLM's are around 160.. Really Lean. That is why the Supercharger isn't getting hooked up until I get this fixed. Timing was way out of wack. There was one point when we let off the throttle the timing went to a -4 degrees for a second. or so.

I did disconnect the knock sensor (Black wire from the White wire) and the scan tool still say's knock. Even with Wire disconnected. Tryed to pump the gas and it really started to back fire hard so I know the knock sensor is working.

I am almost ready to just put the 749 ECM on it, Swap the Map to the 2 bar, and repin the 10 wires and see if that corrects the problem. If she blows, she blows. But why waste a new engine rebuild on stupid stuff.

Could it be a bad knock sensor? I was insured from GMPARTSDIRECTED.COM that it was a 350 sensor. But maybe not the right year? Don't know. Any suggestions would be appreciated.