PDA

View Full Version : Knock sensor bypass wiring with Megaohm Resistor



240Kompressor
02-17-2006, 03:01 PM
Quick question on the knock sensor bypass. I'm throwing the #34 DTC and the wiring appears ok and has continuance. The knock sensor has some small cracks in the plastic housing, but I don't know that it means it is bad. I have seen some old posts mentioning wiring a 1 Megaohm resistor in to fool the computer and stop throwing codes/retarding timing. But the link is no longer working. Does the resistor just need to go in between the sensor harness and ground? Just take the place of the knock sensor?

Or if someone has a surefire way of knowing that the sensor is bad, that would help. FSM shows only a test for continuance between terminal 'A' and ground.

Any help or advice appreciated. Thanks.

EDIT:
Measuring the terminal to the center of the sensor resistance with the multimeter gives a fluctuating reading, but it is generally somewhere near 12 to 15 Megaohms. It does not show continuance on the regular continuity tester setting. Does this mean the sensor is good? FSM is very unclear on this.

-Steve

240Kompressor
02-17-2006, 04:57 PM
I guess I'll answer my own question again. I cleared my codes and spliced the resistor into the sensor harness. Then I grounded it to a valve cover bolt and went for a drive. I got back and pulled my codes. No 34.

Just to be sure, I unhooked it from the valve cover and started the car for 10 seconds. Then stopped and checked my codes again. The code 34 was back.

Then, to be really, really sure; I cleared my codes again and hooked it back up. Started the car and rechecked. No DTC 34.

So that settles it then. The trouble must lie in the sensor, as there is no other wiring between the resistor and the sensor hookup.

I think I know the answer to this, but... it would probably be a bad idea to run without a knock sensor @ 8 to 10 psi? It occurs to me that the AEM EMS that some of you guys use is not compatible with our knock sensor, so several of you may not be using any detonation safeguards. Can this be done safely? Just listen for knock? Forgive my stupidity.

-Steve

dryft_s15
02-17-2006, 05:01 PM
I've run with a bypassed knock sensor for several years on a SR20DET. Just try to make your ears extra sensitive to strange noises from the engine bay.

I find that the car runs a lot more consistently without the KS, but a very bad batch of gas might cause you some problems if you dive through some pinging.

240Kompressor
02-17-2006, 05:14 PM
That's reassuring. I'll be driving with 93 probably from here on out, to play it safe. Did you back off your timing more than normal, or run it the same as if you had the KS in?


Also, the resistor leads are very brittle and soft, how do folks splice it in so it is secure?

dryft_s15
02-17-2006, 05:35 PM
I left timing as is.

I soldered some stranded wire to the resistor (12-14awg will do), rather than bolting the leads directly.

240Kompressor
02-17-2006, 06:06 PM
Good enough. Thanks for the info.

Kookz
02-20-2006, 02:49 PM
Can you elaborate on where you spliced and what side you grounded?

aukalok
02-20-2006, 04:09 PM
Unplug the knock sensor and put the resistor into the two the female slots into the connector.

Kookz
02-20-2006, 05:18 PM
No go...looks like it's time to shell out the money for a knock sensor and fix it the right way.