clearnetedm

Hey folks. I've been playing with the dash command app on my iPhone that can read boost, temps, etc but there is one gauge I've been very curious about. It can read the knock sensor timing adjust?? which I think can be valuable. One thing I don't fully understand is why the gauge is a range from -4 to 4. I always considered knock as either happening or not. So my first question is why does it so negative numbers? I assume plus numbers is the presence of knock and the system pulling timing. If there are negative numbers does this provide more power, etc?

On another note while playing with this over the last few months I have fund some gas to be good and bad. When i'm pulling my trailer I notice 91 Oct gas with 0% ethanol produces the lowest knock ratings. Where as the cheaper 87 with 10% Ethanol almost always stay in the 2-3 range. When not pulling its not as clear one over another.

BTW I have a 2013 F150 EB Max Tow pulling a 7000Lbs trailer.

jcain

- is adding timing + is reducing timing

erick@leadingedgetuning.com

The higher octane from the 91 should produce less knock because of the extra octane, we have even seen this with 10% ethanol...

MAK Performance

The higher the octane you put the lower the knock counts will be. Better fuel = less knock. What your seeing is exactly what should be happening. If you can put 93Octane it will run even better.

clearnetedm

Thanks guys. So would it be accurate to say all gas will produce knock just the lower octane is not producing as much? Just trying to understand why when driving normal it usual stays around the 0 mark, which I always assumed to be no knock. But in reality 0 is just the trucks "Normal" knock but some gas will actually get better thus the negative numbers.

MAK Performance

In reality knock is an event that occurs in the engine(detonation). The ecoboost pcm is a bad example of what knock actually is. The parameter should be labeled "knock retard".

Detonation is an event that occurs in the combustion cahmber when the incorrect mixture of fuel/air/spark is present.(Mixture ignites prematurely) For the most part what we all refer to as detonation is related to too much timing or not enough fuel. This condition can and will cause engine failure.

The parameter that you see as negative and positive is degrees of timing being pulled. It is a way of regulating that mixture to an acceptable level before damage is done. So when you see "negative knock" the engine is running great and is not detonating so the computers sees it fit to add timing to give you more performance.

When you see "Positive Knock" the engine sense detonation via the knock sensors and the computers compensates by pulling timing in order to put it back into the acceptable range.

That was as quick and detailed explanation I could write(customers in the office.) Feel free to ask if you have any questions.

F150Torqued

@MakPerformance - I KNOW THIS IS AN OLD THREAD. But, that was a great "101" on Knock Retard. AND, I gotta' question if you or any of you guys know the answer. //// WHAT IS THE SPECIFIC OBDII PID# FOR THE PARAMETER "knock retard" and or "retard decay"? ////


I have used Torque Pro for several years and have hacked the hell out of the OBDII system on my 2004 5.4L Triton. I've used TorqueScan to scan & log every possible PID # that responds to queries - (around 220 different PID's on my specific vehicle configuration). I have identified about two-thirds of them, and created lots of very useful custom gauges that display lots of really good stuff. But I cannot identify "knock retard" or a "retard decay" constant.


I know that the Knock "Sensor" bank 1 (KS1) is # 16E6, and KS2 is # 16E7, but the sensors are basically microphones and their output is analogue proportional to noise detected. (I've got gauges that display those in volts). Excessive noise effects ignition timing negatively and fuel trim positively. BOTH conditions are adverse - to performance and fuel economy. How much ignition timing is being retarded (knock retard), and knock retard decay (how long it takes to recover to normal) would be invaluable diagnostics information.

Ignition advance is available, and of course I have a gauge for that - but it would be nice to know if THAT reading is being (or has been) REDUCED by knock sensors noise levels (even a little bit), since retarding timing has such a dramatic effect on power.

TIA Any-- appreciated

violinguy77

Knock

Notes on how this PID works: This PID will vary from -4 to +7.5 although we have some people that say they've seen a -5. If the number is negative then it is adding timing in real time (this is good)...if it is positive it is knocking (this is bad). A couple of degrees isn't a big deal and the general consensus seems to be under 5 should be okay if you aren't highly modified. The ECU is supposedly able to subtract a maximum of 7.5 degrees of timing and won't read any higher (not verified by me personally and may be tune dependent).


One note: Do NOT use spaces in the equation and pay careful attention to the () or you will get weird results.

PID 2203EC
Torque Equation - ((signed(A)*256)+B)/512

F150Torqued

@violinguy77


Thanks a million for your response. I have seen "03EC" listed in print before, and that formula - I think relating to late model Mustangs and perhaps late model Ford 5.0 engines, and I think related to Ford Focus. The lack of standardization is infurriating (if that is the issue), but the ECU on my 2004 Lariat with 5.4L 3v Triton does not respond to an OBDII querry to 2203EC - whether using header of "blank", or "Auto", or "07E0".


HOWEVER- I am going to go back and do some more hacking on that port and experiement with some other headers, and maybe some "start diagnostics commands" to see if there is something different about that PID that keeps if from responding to TorqueScan or a standard Mode 2 ObdII query in Torque Pro. (That is on MY vehicle anyway).


Thanks again buddy. And if I get anything new - I'll post it back here.