I've been looking for the information on using an external knock filter or "ESC" with a 1227730/1227749 style ECM.

I have found some information, about feeding the input to an ECM, but I recall there was more to modifying the MEMCAL than just removing the knock filter, I was sure there was a jumper needed, and maybe even a resistor to bias the input to avoid a malf code.

I recall seeing a thread a few years ago with pictures of the modification, but can't locate it.

Any in sight or a link to a thread with more specific info than I have found would be great.

I have found these:
https://www.thirdgen.org/forums/dfi-...165-730-a.html RBob seems to indicate that only external hardware modifications are needed, specifically connecting the ESC output to pin B8 of the '7730 and then tying F9 (the original KS input) to ground to avoid the malf code.

https://www.thirdgen.org/forums/diy-...cal-730-a.html A little more vague, but seems to indicate similar.

If it's as easy as connecting the ESC output to B8, and either tying F9 toground through a 3.9K ohm resistor, or disabling the malf code, then that would be nice. I just recall there being more to it.

FWIW, I'm making a jumper harness to use a '7730 or '7749 (I haven't decided which one yet) in a Turbo Regal, and would like to have this adapter as plug and play as possible. If I can use the existing ESC easily, it will make this much easier.

post #62

http://www.gearhead-efi.com/Fuel-Inj...hlight=1227730

That is all there is to it. Although instead of the 3.9K to ground I'd look for a way to disable that malfunction in the calibration. While leaving the run-away knock count malfunction active.

Most likely could set the high limit on the ADC check of the sensor to the max.

RBob.

Thanks, that wasn't exactly what I recall seeing, but it is definitely helpful. I have a modded MEMCAL now that I will try in this car.

Why would you leave the runaway knock count going?

Disabling the MALF code will be easy, I'll be using $58 in this application.

The run-away knock count malfunction is caused when the wire from the module to the ECM goes open, or the module loses +12 volts. It is another check of the ESC system.

Basically, if knock counts are run up non-stop for 3.9 seconds, then something is wrong.

However, you posted about using $58, it doesn't have a run-away knock count malfunction. The ADC test is there, but instead of run-away knock counts there is a premium fuel test for counts. Too many counts and the SA is reduced. Sorta' the same thing as run away, just not a malfunction.

RBob.

curious on the 85-89 tpi esc part numbers. acdelco shows a listing on acdelco.com gm 16126761 acdelco 216-45 shows the esc module for vin f and vin 8 corvette and camaro lb9/L98. I have one off a 85 tpi 305 with the numbers 16022621. I know frequency of the knock sensors are different but does the external esc work with both filter frequency's ?

16126761 (ANRZ) is discontinued. Replaced with HKR for the 4.3l & 5.7L engines, and HKM for the 5.0l engines.

16022621 (BLH), is for 2.8l, 5.0l, and 5.7l engines. I have had good luck with that filter on several different engines.

RBob.

Thanks again rbob