LT1 24x Conversion - No knock retard, ever.

Hello,

I have a 383 LT-1 which has been converted to run a 411 PCM with coil per cylinder ignition. The problem is, no matter what I do to the tune, I never see knock retard. This has me worried and thinking I've messed something up in the tune or knock sensor wiring.

For example, I tried the trick of hitting the block with a screw driver and still got zero knock retard.

I have tried pushing advance slowly up to 50 while idling, and no knock.

Can anyone provide some tests I can do? If I backprobe the knock sensor pins, is there a voltage or resistance I can look for?

Which knock sensors are you using...?

GM 10456287, which is the LT1 knock sensor. Its the same knock sensor used in the 2001 GMC 5.7 van, which is the factory SBC using the 411 PCM.

Are there sets of tables used to configure the pcm for the knock sensor?

You may have to use the calibration file from the 2001 GMC 5.7L van (i.e. the PCM may be tuned to the knock sensor type).

Edit: I meant copy all the knock sensor tables/parameters

Thats an interesting idea. However, since I've got coil per cylinder ignition, I think it wouldnt start as the van tune is expecting a distributor.

I think he meant to copy all the knock sensor tables from that calibration.

I know this is an old post. I had the same problem with a 411 swap on an LT4. After modifying the tables using the 2002 L31 parameters, I had to zero out the {B6244} Knock sensor multiplier "A" I then reduced the {B6245} multiplier "B" table 50%. {B6246} and {B6247} also set to zero. {B6250} and {B6255} reduced 75%. I hope this helps. (P.S. remember to set {B6201} value to 1)

Quote:

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Originally Posted by Tom B.

I know this is an old post. I had the same problem with a 411 swap on an LT4. After modifying the tables using the 2002 L31 parameters, I had to zero out the {B6244} Knock sensor multiplier "A" I then reduced the {B6245} multiplier "B" table 50%. {B6246} and {B6247} also set to zero. {B6250} and {B6255} reduced 75%. I hope this helps. (P.S. remember to set {B6201} value to 1)

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Tom, Thanks,

I am going to post something soon that should solve this issue.

Quote:

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Originally Posted by Highlander

I am going to post something soon that should solve this issue.

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I'd be interested in this as well.

I have a SBC400 with x24 conversion that uses a COS 01290003 tune but using the old TPI knock sensor and I don't get any knocks logged at all.