Disconnecting Knock Sensor

[ToroGTS]

Will it cause the ECU to go into limp mode or otherwise effect performance if the knock sensors are disconnected?

[h4X6]

Yes.

There is a way around it tho I've been told. You have to wire in a resister to foul the ecu into thinking its there and working. Haven't looked into myself. But I will be if my new knock sensors don't work.



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[ToroGTS]

Does anyone know what resistor should be used?

[Skym]

Limp mode is when you can't access Consult and it can happen when EPROM chip dislodges from main circuit board. Supposedly runs engine rich, etc.

I know from someone that had a knock sensor failure, that ECU can activate a revlimiter (he mentioned it wouldn't rev above 5000rpm, which is where safety revlimiter is). But usually safety revlimiter only engages when there's 0km/h input from speedo (these settings are adjustable on ECU via using Nistune).

[ToroGTS]

I suspect I might be having an intermittent signal from the knock sensor, haven't physically checked yet due to unease of access... what is the best way to trouble shoot or diagnose. Can they be resistance tested?

[Skym]

Engine manual should have the info (voltage range) in the back for sensors -

http://www.jpnz.co.nz/afawcs0131170/CATID=24/SUBID=273/page=1/products.html

[ToroGTS]

Pulled the knock sensors to see what would happen. Initial issue I suspected did not clear up and additionally the ecu would not advance timing under boost and it felt basically gutless.

[h4X6]

what is the underlying issue? same as me? where it runs fine until 4500rpm then it just is gutless and hesitates

btw i found out what u need to do for wiring in a resistor to trick the ecu into thinking all is well with the knock sensors... now keep in mind, doing this will mean that the ECU will never detect detonation and will not adjust timing and the possibility of blowing up your engine is higher... i also now have some rb20/25 knock sensors for sale if you need new ones...

you take a 1m ohm resister (preferably a 1/4watt, but 1/8watt will work too) and wire one end to the signal wire and the other to ground. now you can either do this on the wiring in the engine bay or at the ecu. i am doing it in the engine bay as im doing it in a way that if i need to remove it and plug back in the knock sensors i can

[Skym]

Stock ECU looks for knock at lower rpm's, then pulls ignition timing and switches to knock maps if necessary at higher rpm's. Above lower rpm's engine gets too noisey and hard to determine what is knock and what isn't (ECU will report knock count figure, but won't do anything about it). This is the same for most stock ECU's.

If ECU detects knock it can pull ignition timing from roughly 3500rpm to 6000rpm, which is what happened on my cars dyno chart and torque dropped and created a V look in torque plot (minor drop in power plot).