Knock Sensor, Knock Filter, ESC and swaps!

[JeepsAndGuns]

I was typing when you posted that. I went a got a BJYL memcal (95 5.7 TBI $0D) and measured it. Now bear with me as I am using a cheap craftsman multimeter. With it on the 20k setting, it reads 0.86, on the 2000 setting, it reads 865. The number in the red circle is 26.

Next I tested a BNKM memcal (95 P30 5.7 TBI $31) On the 20K setting it measures 2.26, on the 200k it measure 2.6, on the 200 setting it reads nothing. The number in the circle is 34.

Tested a BJYM, it tested the same as the BJYL, same number too on the board.

Last I have is BJKW (95 7.4 TBI $0E) it measured the same as the BNKM memcal and has the same number on the board.

Now that is really strange, seeing as how BNKM is a 5.7 memcal, bcc find puts it as 5.7/4L80E, and I specificly remember pulling it from the van and it definately had a 350. Yet it appears to use the exact same knock filter as a 7.4.
Humm (scratches head)

[RobertISaar]

So could you simply jumper the TBI memcal for MPFI, replace the chip with a EEPROM and have a useable V8 TPI memcal?

hell of a lot better than what some people are doing.

I was typing when you posted that. I went a got a BJYL memcal (95 5.7 TBI $0D) and measured it. Now bear with me as I am using a cheap craftsman multimeter. With it on the 20k setting, it reads 0.86, on the 2000 setting, it reads 865. The number in the red circle is 26.

Next I tested a BNKM memcal (95 P30 5.7 TBI $31) On the 20K setting it measures 2.26, on the 200k it measure 2.6, on the 200 setting it reads nothing. The number in the circle is 34.

Tested a BJYM, it tested the same as the BJYL, same number too on the board.

Last I have is BJKW (95 7.4 TBI $0E) it measured the same as the BNKM memcal and has the same number on the board.

Now that is really strange, seeing as how BNKM is a 5.7 memcal, bcc find puts it as 5.7/4L80E, and I specificly remember pulling it from the van and it definately had a 350. Yet it appears to use the exact same knock filter as a 7.4.
Humm (scratches head)

gah, i hate non-autoranging multimeters...

so:
BJYL = 26 / 865ohms
BNKM = 34 / somewhere between 2260 and 2600 ohms(probably closed to 2260)
BJYM = 26 / 865ohms
BJKW = 34 / somewhere between 2260 and 2600 ohms(probably closed to 2260)

and the first 3 are 5.7, last is 7.4... 5.7 = 4" bore, 7.4 = 4.25" bore (or 101.6mm and 107.8mm)

yet both use not only the same sensor, but the same filter as well? 5.7 has a knock frequency of 5642Hz, 7.4 is 5310Hz... they're actually not very far off.

based off of the knock filter document, they both PROBABLY used a filter based around 5KHz, as does at least two 4.3(4" bore) applications(3 others are centered on 7KHz).....



so either GM cheaped out and didn't make new filters when they should have(and false knock could be detected or worse, real knock ignored) or it's not as clear-cut as it seems?

[RobertISaar]

put the knock filters together for a little comparison... i probably should have grabbed the 3.1 MEMCAL, but i can do that later if necessary....

http://i.imgur.com/AJKnl5J.jpg

the MEMCAL with the 27SF512 in it is the 91-93 version, the one with the factory PROM is the 94-95. note that the size of a few components changed, but otherwise they all seem to be in the same location. some portions of the traces stayed the same, but that changed quite a bit too.... notice that the blue layer can have both traces above and below it on both. i have to wonder what the little component is in the center.... seems like it would be an IC, definitely something custom made for Delco. lots of laser-cut resistors too.

have to wonder how difficult making a DIY knock filter would be..... doing the bandpass calculation(for a given bore size) isn't too bad, but then just have to figure out a way to ground the circuit that signals knock to the processor.... and then having a method to allow for sensitivity adjustment...

[JeepsAndGuns]

I probably should have grabbed the 3.1 MEMCAL

I have a couple of those. I tested a AXKK memcal, which comes back as a 92 3.1 auto.
On the 200k setting it reads 25.7, on the 2000k setting it reads 25. I reads nothing on the other settings. The number is 09

[EagleMark]

I've spent so much time reading about all that has been uncovered and got a headache a long time ago! Everything I found says that GM changes knock filters and ESC more then they changed ECMs. Since then I use a ECM/PCM with ESC or Memcal and knock sensor from same vehicle that has simalar cubic inch for conversions and all the netres LHM and knock sensors work!

I don't know where this chart came from but it convinced me not to mis match parts.

[1project2many]

On the 200k setting it reads 25.7, on the 2000k setting it reads 25. I reads nothing on the other settings.

You shouldn't keep using different settings on the meter. Use the lowest setting that's appropriate and take that reading. Increasing the resistance range makes the reading "less fine" and increases the voltage used to make the measurement.

[Six_Shooter]

You shouldn't keep using different settings on the meter. Use the lowest setting that's appropriate and take that reading. Increasing the resistance range makes the reading "less fine" and increases the voltage used to make the measurement.

I was just about to say the same thing.

When using non-autoranging DMMs you use the lowest setting that shows a value other than "OL" or "0.0".

On a 200K setting the max range is 200 000 ohms, so a reading of 25 on this setting is 25 000 ohms. Using a a range setting of 200, and reading 25, the result would be 25 ohms.

[RobertISaar]

I have a couple of those. I tested a AXKK memcal, which comes back as a 92 3.1 auto.
On the 200k setting it reads 25.7, on the 2000k setting it reads 25. I reads nothing on the other settings. The number is 09

i'll have to grab the wife's camera and take a pic(and do measurements) of the 3.1 i have as well... apparently there are multiple listings for the 3.1s, i can think of 3 unique versions that most definitely used a P4 ECM (FWD Aluminum head 3.1, Turbo FWD Aluminum head 3.1, RWD Iron head 3.1), though there may have been more. i don't think there were any iron-head FWD that used the P4(think they were C3, one year only from what i remember), and i don't think the U-vans with the iron FWD TBI engine ever updated to P4.

[Six_Shooter]

Quick search for early '90s Pontiac Transport, brought up this listing on ebay:

http://www.ebay.com/itm/GM-DELCO-ECM...sories&vxp=mtr

Ludis's reference brings this up:

http://www.exatorq.com/ludis_obd1/c3xref.html#16149405

The '7730 was used on an early I4 application:

http://www.exatorq.com/ludis_obd1/p4xref.html#1227730

[RobertISaar]

that covers 90-93 as being C3 then. 16196391 used for 94-95 and it's also a C3... so i don't know why there are at least 3 different 3.1 filters.