Hey guys, just wondering how many of you use the OEM knock sensor when adjusting your timing maps. I am using the Haltech Platinum right now and running about 4psi of boost, this is according to Haltechs MAP sensor. My boost gauge reads about 5.5psi but this is a cmopletly different issue all together. Hal from IP and I are emailing back and forth, awesome technical support by the way. I am sure we will get to the bottom of it soon.

So ya, I just wanted to see how many of you are are using it and how reliable it is.

IIRC I read somewhere that it becomes useless above 5500rpm, any truth to that?

 

Might want to contact with who running with uprev. Yea that's what i heard OEM knock sensor can read above 5k RPMS.

 

Utec uses the OEM knock sensor but you can adjust the sensitivity in Utec for every 1k rpm. I would assume you can do the same with Haltech.

 

I tried to set it up last night, the haltech is picking things up but the voltage is what seems to be out to lunch.

I searched this forum last night for about one hour and found that the stock knock sensors voltage usually sits at about 2.53V. I also found out that anything above 2.6V should be considered as knock. So that' fine

However, my voltage displayed on the Haltech is 0.x0xV. I get spiked while accelerating in vacuum. I know it's not knocking, and the voltage doesn't go up much, maybe 0.3xV. I know that it needs to be calibrated, and I played around a bit with no luck.

I wish the Haltech manual was better.

 

You can try shoot PM to frankie945, he is using haltech and he likes to play around. I bet he can help you out some point.

 

Well Nissan deems it to be useless about 5k rpms. They spec the sensor, and they know the motor. There is headroom in the DSP that the knock sensor uses so it's not that. It's just that the knock sensor sends unreliable info above that point.

Knock sensors aren't magic, they don't even pick up knock. They are just a microphone for all intents and purposes. It's what the DSP (digital signal processing) does with that noise to figure out what is knock and what is typical noise. A spike in voltage from a knock sensor doesn't mean that it's knocking. Thats why stand alone and piggy back ecu's look for a certain number of spikes, over a certain voltage, over a certain amount of time, and they just figure if it meets those criteria then it must be knock.

Problem is, you could destroy a motor with a single solid detonation, let alone 4 detonations over 2 seconds. The factory ECU doesn't even wait for what it deems to be a full knock, it listens to the noise the knock sensor is sending and it compares all the other variables in the ECU to determine if knock will occur. Which is why the stock ECU is safe.

 

The problem here is that you can drive normally and not knock/detonate until you hit high boost and higher rpm. For example, you can be lining up on a freeway and downshifted to 3rd@5000rpm gracefully while waiting for your opponent to catch up. Now that you are ready you go WOT at 5000rpm and let say with a little LAG you hit full boost at 5400rpm. I bet you on that entire race your rpm will never go down below 5000rpm so you can be detonating the entire time and the ECU is just sitting there not doing anything.

 

So basically one should pull back on the timing, up the boost and tune the fuel. This to me sounds like the safest bet. When I say up the boost, I mean go up untill you are at your desired power level. For example, I am looking to make about 370whp, so whatever that boost ends up being. I know my turbo will be able to support well over 500whp so it wouldn't be straingin at all.

Sound about right.

 

A great tune will not protect you from failing injector, bad tank of gas, overboost..etc I experienced all of them and no prefect tune can protect you from it. When I did get a bad tank of gas (twice and thanks to Mobile), my car run fine until I hit 4+ psi. You just cant predict when knock is going to happen so a good active knock control is a must in my book.. just my .02. Also a good ECU/EMS base overboost fuel cutoff is a nice feature because boost controller wont protect you if your wastegate fail to open or controller failing..

 

This is all true. All I can do is reduce the chances of knock events and prolong engine life. Things like bad injectrs and bad fuel are out of my hands. Things like timing and overboost protection are, and the Haltech is set to cut fuel at a certain boost level, so that is fine. This is why I started this thread, I want to do all I can to prevent problems.

I will probably never run more than 8psi of boost on a stock motor, so whatever I can get out of that I guess. It should be plenty to get me to 370whp.