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View Full Version : Knock count with engine off?


brianko
12-13-2014, 07:13 PM
What would cause knock counts on a '94 454 to increment with the engine off? ECM/MEMCAL issue?
BJLF/16196395 (http://www.gearhead-efi.com/Fuel-Injection/showthread.php?3967-Running-a-454-TBI-with-a-4L60E-should-be-possilbe-with-BJLF-16196395-right)(Yeah, I know it's a 350 calibration, that's another issue currently being worked...)
JeepsAndGuns
12-14-2014, 03:28 PM
The knock sensor modules in the memcals are engine specific. A 350 knock filter is not gonna work right with a 454 engine. You really need a 454 memcal.
brianko
12-15-2014, 01:44 AM
The knock sensor modules in the memcals are engine specific. A 350 knock filter is not gonna work right with a 454 engine. You really need a 454 memcal.

I thought the only circuitry in the MEMCALs (other than the PROM) was the limp-home circuit, not a separate module like in the old-style LT1 PCMs. Are you sure about this? I've not read this anywhere else...everything I've seen indicates the V8 MEMCALs are interchangeable.
JeepsAndGuns
12-15-2014, 03:20 AM
If you remove the blue cover on the memcal, you will see the knock sensor module. You can see part of it through one of the little "windows" in the cover. Its on top of the limp home chips.
And yes, they technically will interchange, but that doesnt mean they are right. The limp home chips are the same for 5.0, 5.7, 7.4, but the knock sensor modules are different. They will work, but as you have found out, they will not read correctly and can pickup false knock, or not pick up knock when there actually is some.
brianko
12-15-2014, 04:10 AM
If you remove the blue cover on the memcal, you will see the knock sensor module. You can see part of it through one of the little "windows" in the cover. Its on top of the limp home chips.
And yes, they technically will interchange, but that doesnt mean they are right. The limp home chips are the same for 5.0, 5.7, 7.4, but the knock sensor modules are different. They will work, but as you have found out, they will not read correctly and can pickup false knock, or not pick up knock when there actually is some.

Learn something new every day. Thanks for the learning opportunity.