slinkyeleven

I keep getting a code 12 on my pickup. This DTC definition is for the knock sensor. I have a hesitation off idle or when the throttle is snapped wide open in neutral or in any manual gear. This is most noticable at light throttle / cracked to less than 1/4 opened. At WOT or 1/2 + it has full power. Timing is at 5 degrees with the connector shorted, tps has been set multiple times with a feeler gauge, the knock sensor has been swapped and the coaxial cable to it from the ecm has been replaced with the ground being repaired. An new coil, tune up components, fuel filter have been installed. The EGR main vacuum supply has been plugged with a screw to test if this was the issue but now change exists. I am stuck any ideas?
Thanks
David

85 toy pickup 2.4 fi code 12 issue

notanymore

keep us posted because i have a similar problem with code 12, i havnt spent alot of time looking at the cause but i do have some hesitation/power loss, but i thought i was getting that from having a plugged cat

gametom

i have seen a broken motor mount cause a knock code on a honda. and you might want to test the maf it may have something to do with the hesitation

slinkyeleven

Replaced the ECU with another unit from a Furmann's Salvage in Santa Ana, CA and have yet to see the MIL illuminate since then. I have never replaced an ECU in all the time I have worked on vehicles but this one fixed it. If you have this code 12 follow these steps first.

-Backprobe the ECU KNK pin with the pos. lead and ground the other lead of the DVOM. Start the vehicle and with the meter on the Freqency / Hz scale. The readings I had with both the old ecu and the new are 0 at idle and ranging between 1 - 2/3 K Hz. A lower reading is found off idle rpm and at full throttle 2-3 thousand (K) Hz are displayed.
-If you do not get this reading you either have an issue with the wiring to the sensor or the sensor itself. Measure continuity from the terminal on the sensor connecter to the KNK pin at the ECU. If you clear this code and it still resets, just repair the wire with RG58 coax cable and solder / secure the ends.
-Checking the sensor - Use a DVOM and measure the Hz output with the pos. lead on the knk sensor terminal when installed in the engine and the other lead to ground. Tap on the intake manifold with a hammer to generate a knock / vibration. The meter should show a frequency. These sensors are quite reliable and unless the engine has been severely overheated generally do not fail.
If the wire has been repaired, the knock sensor test ok and a signal is generated to the ECU while running, the ECU is the remaining component for this code 12.

Thanks for all of your help

David