I'm getting my wires ready for my 0411 pcm swap onto my stock tpi 350 and have a question about the knock sensor wiring. The stock 350 knock sensor only has one dark blue wire running to the sensor but the 0411 knock sensor has two wires running there. A dark blue wire and a light blue wire. Would I only use the dark blue and eliminate the light blue from the pcm? Or would I just ground the light blue wire?

 

Dark Blue is sensor 1
Light Blue is sensor 2.

 

@Fast355 Could probably help you out here. I know he had messed with 0411 stuff before in his Vans.

What tuning software are you going to be using to tune your 0411 PCM?

Which base OS tune file are you going to be running for your L98 engine?

Does that base OS tune expect to be seeing a 1 wire resonant knock sensor or a 2 wire flat response knock sensor? Does it expect to be seeing 1 or 2 knock sensors?

The knock sensors (1 or 2) you use is going to have to match what your 0411 PCM and base OS tune file wants to see and the engine's bore size. You don't want to run a knock sensor for a 305 bore size engine on a 350 bore size engine.

There may be options to change the knock sensor configuration around in the tuning software.

Note: I'm no expert on this subject. I've never done it before. I do believe you just can't do whatever here and that things need to be matched together to work correctly.

 

JMD, my 350 only has one knock sensor.

 

Airwolfe, I was just going to run the factory knock sensor that's already there if my pcm allows me to do so. As for tuning I am having a friend of mine near Sacramento do the tune. Not sure what he has.

 

Yep. The 2002 vans with 350s had two.
Your current sensor and the drain plug on the other side can be replaced with two for a 350 van. Not a 305 van. Bore size changes sound of detonation.

 

So I can pull the cooling fan switch and put another 350 knock sensor in it's place? I already have a switch to turn the fan on manually.

 

The 350 vans only have 1 knock sensor. 4.3L had two and they were 2 wire flat response. The 350 I pulled from a 2005 Silverado 3500 and have the P59 Green/Blue PCM tune from only had a single knock sensor as well. The only 350s with dual knock sensor were some LT1s and Marine application. I do have dual knock sensors on my L31 based 383. I changed the tune to dual knock sensor and mirrored the knock sensitivity settings from Bank 2 into Bank 1. The stock single knock sensor settings are extremely sensitive on Bank 1 because of the distance the knock sensor is from the combustion chambers of Bank 1. Adding the 2nd sensor and mirroring the sensitivity settings for Bank 2 that were much lower values really cut down on the PCM retarding timing for false knock from vibration and valvetrain noise.

 

This may also sound goofy, but the 1996 LT4 Corvette actually used the 305 knock sensor not the normal 350 one. I used 305 knock sensors on both my 350 and 383 with no ill effect. Did exactly what GM used them for in the LT4. Kills false knock with the roller rockers.

Edit--IIRC all the OBD2 LT1 engines used "305" knock sensors not just the LT4. The LT4 had its own desensitized knock module though. Changes to the knock detection were a highlight to the LT4 changes though in GM Engineering literature at the time. I used Delphi sensors myself.






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Knock sensor goes in the block drain at the bottom of the engine coolant jacket. Center of the block, right above the oil pan rail where your current knock sensor resides. The block drains were existing on both sides of the SBC engine block long before knock sensors existed.

 

Yes I know that is where they go and have known that what they (the block drains) are used for. I appreciate yours and everyone else's inputs. Thank you.