Knock sensors...

ablexus · 09-01-2006, 11:55 PM

How many are there in this truck, 1 on each cylinder bank or 1 total? Where are they exactly?

Yes, I'm looking to unplug mine.

Andrew

SOCALTITANKC4X4LE · 09-02-2006, 12:08 AM

Andrew, there are two knock sensors, one on each bank. If you unplug them you will get one or more Diagnostic Trouble Codes ( DTC ).

Tony

gyrate · 09-02-2006, 12:27 PM

knock sensors are there to protect your engine from bad detonation.. they are really something that you shouldn't tamper with

ablexus · 09-02-2006, 01:25 PM

Thank you both for your concern, the DTC's are something I'm looking at ways of bypassing, and the effects of unplugging them are minimal, if not nonexistant with higher octane fuel.

Remember how rich we naturally run, a deterrent to detonation. In addition, I pose this question: How did big V8's run for decades without knock sensors?

Andrew

BKW · 09-02-2006, 01:39 PM

Quote:

Originally Posted by ablexus

Thank you both for your concern, the DTC's are something I'm looking at ways of bypassing, and the effects of unplugging them are minimal, if not nonexistant with higher octane fuel.

Remember how rich we naturally run, a deterrent to detonation. In addition, I pose this question: How did big V8's run for decades without knock sensors?

Andrew

First V8 engine...1915 Cadillac

First knock sensor...1980's.

Leaded Ethyl gas was introduced in the 1920's

Knock sensors are needed today, cuz lead is a thing of the past.

BKW · 09-02-2006, 01:45 PM

I meant to add that with the addition of leaded gas, pre-detonation was mostly eliminated.

Getting a pre 1980's car tuned and timed was a yearly necessity.

So when the lead was removed, it was necessary to come up with something to keep vehicle from pinging.

Knock sensors

Mr. B · 09-02-2006, 02:21 PM

I'm thinking about upgrading my knock sensors to doorbell chimes.....you know, bring myself up a couple of notches....technilogically speaking.

RB's Titan · 09-05-2006, 03:01 PM

Andrew - two sensors...underneath intake manifold at back of engine. It's my suspision that the ECU is controlling retard before the knock sensors signal. I guess you have seen the nitrous Cipher data logs under N20. There is a trigger baried in the code that I hope someone can figure out...and or figure out how to change the retard map.

ablexus · 09-06-2006, 12:46 PM

No, I haven't seen those, but I'd love to. Link?

If the retardation is effected before the knock sensors trigger, that would essentially make the sensors useless except in extreme situations... which I haven't encountered yet. So in they stay, for now.

Andrew

RB's Titan · 09-06-2006, 01:39 PM

Quote:

Originally Posted by ablexus

No, I haven't seen those, but I'd love to. Link?

If the retardation is effected before the knock sensors trigger, that would essentially make the sensors useless except in extreme situations... which I haven't encountered yet. So in they stay, for now.

Andrew

There was and engine on ebay not long ago that showed the back of the engine and you could just barely see them...of course I knew where to look based upon the service manual.

ablexus · 09-06-2006, 01:41 PM

Green plugs?

Andrew

StuntDriver06 · 09-06-2006, 01:59 PM

knock sensors are a must for engine survival today.. the comp (in some situations) under full throttle tries to run max timing until a knock is sensed.. usually before anyone could ever hear it, then timing is retarded to prevent engine damage. if you disconnect them then run up a hill at full operating temp, you might get harmful detonation...

RB... i have learned as a general across OBDII vehicles that timing is usually retarded to meet emissions/economy standards... thats why aftermarket flashes/tunes/chips provide better power.... nissan just happens to use proprietary software in their ECU and it is real hard for anyone to crack the code without access to the right stuff, which im sure they dont let out... companies like technosquare often go through lines of code to see how the ECU was programmed, then experiment to see what they can do...so... the retard you are seeing is likely a built in curve (that can change based on conditions like engine load and temperature, or octane of fuel) that was put in place to give the best emmisions/economy... i know on my dodge dakota, i was able to log some info from the ecu at a buddies place, he told me that the factory settings allowed a max of 22 degrees of ignition timing when i could use around 32-38 (depending on temp) with 93.. just my $.02

PS: didnt mean to hijack

RB's Titan · 09-06-2006, 02:06 PM

Quote:

Originally Posted by ablexus

Green plugs?

Andrew

They are black..but hey I'm color blind could be evergreen...LOL

Timster13 · 09-06-2006, 02:29 PM

Quote:

Originally Posted by ablexus

Thank you both for your concern, the DTC's are something I'm looking at ways of bypassing, and the effects of unplugging them are minimal, if not nonexistant with higher octane fuel.

Remember how rich we naturally run, a deterrent to detonation. In addition, I pose this question: How did big V8's run for decades without knock sensors?

Andrew

I'm trying to understand what you expect to gain by eliminating them.

I was also thinking that perhaps we should do away with antibiotics too. How did people live without them back in the 1800s?

RB's Titan · 09-06-2006, 02:31 PM

Quote:

Originally Posted by StuntDriver06

knock sensors are a must for engine survival today.. the comp (in some situations) under full throttle tries to run max timing until a knock is sensed.. usually before anyone could ever hear it, then timing is retarded to prevent engine damage. if you disconnect them then run up a hill at full operating temp, you might get harmful detonation...

RB... i have learned as a general across OBDII vehicles that timing is usually retarded to meet emissions/economy standards... thats why aftermarket flashes/tunes/chips provide better power.... nissan just happens to use proprietary software in their ECU and it is real hard for anyone to crack the code without access to the right stuff, which im sure they dont let out... companies like technosquare often go through lines of code to see how the ECU was programmed, then experiment to see what they can do...so... the retard you are seeing is likely a built in curve (that can change based on conditions like engine load and temperature, or octane of fuel) that was put in place to give the best emmisions/economy... i know on my dodge dakota, i was able to log some info from the ecu at a buddies place, he told me that the factory settings allowed a max of 22 degrees of ignition timing when i could use around 32-38 (depending on temp) with 93.. just my $.02

PS: didnt mean to hijack

We are getting more peak timing when engine is cold vs warm that is for sure. However the highest I have ever logged with cipher and it was engine cold 120F coolant and the value was 32 after warming the same day coolant 188F timing was 27 in same spot.

Also the problem is in the 3-4K range timing drops off in the middle of your 1st gear WOT pull with 100% load. That's why you feel that surge around 35mph and more specifically 4400RPM. Perhaps our engines have issues in that range and Nissan built in the retard based upon the actual detonation capabilites of the engine itself?

Here is two data runs done same day...NA vs N20. Both runs are retarding timing in the same areas.