I have a fairly well cared-for 2009 RTL with right at 100,000 miles. I know the original owner (my brother's father in law) and the truck's service history. The engine has a very repeatable spark knock/ping, and it occurs under certain conditions that I can easily repeat. I believe very strongly that this is spark knock and not the heat shield problem. (I don't think my VIN is included in the heat shield TSB anyway.)
I get a light-but-consistent knock when engine loads are above 80% (OBD-II engine load). At loads that high, the PCM removes EGR from the engine because combustion can become unstable at such a high load with inert gas. At this point, I believe it relies entirely on its preset spark mapping and the knock sensor to determine spark advance. I can watch engine load, spark advance, and EGR commanded/EGR error on my phone with Torque app and, again, I can very repeatedly call up knock by putting enough load on the engine that EGR % goes to 0% and I then begin to hear knock. So I don't believe I have an EGR problem -- the computer is actually calling for no EGR. It'd be one thing if it were calling for EGR and not getting it, but it's commanded the EGR valve closed under these conditions. So I don't think the EGR system plays into this at all (in terms of a bad EGR valve, EGR tubes being blocked, etc).
I do not have any current or stored codes in the computer. My question is, can a knock sensor get lazy and not report knock, and also not set a code at the same time? I've run a few tanks of premium fuel through it, and it doesn't seem to make a lick of difference. It will knock at higher engine loads, and immediately back off if I lift off the throttle (and EGR comes back in). I can apply more throttle, and as long as load stays low enough for EGR to persist, the knock stays away. It's almost like a "mode" or "phase" switch. I don't have a reliable way to determine if it's doing into fuel enrichment correctly. The highest fuel flow rate I've seen is about 14 gal/hr. Are my injectors actually delivering that? I don't know. After periods of heavier throttle, I do smell that "stinky catalytic converter" smell, so it seems that it is enrichening the mixture over normal.
Any ideas? There are few threads on here about spark knock, so it makes me think it's not "normal" and that I perhaps have a lazy knock sensor. My other vehicle is a 2005 Acura MDX with a very similar engine. That engine never has given us the first bit of knock, so I know these Honda engines CAN be knock-free. I'm just not sure what is normal for the newer engines (my 2009 has the newer J35Z5). Any ideas or comments are appreciated.
I get a light-but-consistent knock when engine loads are above 80% (OBD-II engine load). At loads that high, the PCM removes EGR from the engine because combustion can become unstable at such a high load with inert gas. At this point, I believe it relies entirely on its preset spark mapping and the knock sensor to determine spark advance. I can watch engine load, spark advance, and EGR commanded/EGR error on my phone with Torque app and, again, I can very repeatedly call up knock by putting enough load on the engine that EGR % goes to 0% and I then begin to hear knock. So I don't believe I have an EGR problem -- the computer is actually calling for no EGR. It'd be one thing if it were calling for EGR and not getting it, but it's commanded the EGR valve closed under these conditions. So I don't think the EGR system plays into this at all (in terms of a bad EGR valve, EGR tubes being blocked, etc).
I do not have any current or stored codes in the computer. My question is, can a knock sensor get lazy and not report knock, and also not set a code at the same time? I've run a few tanks of premium fuel through it, and it doesn't seem to make a lick of difference. It will knock at higher engine loads, and immediately back off if I lift off the throttle (and EGR comes back in). I can apply more throttle, and as long as load stays low enough for EGR to persist, the knock stays away. It's almost like a "mode" or "phase" switch. I don't have a reliable way to determine if it's doing into fuel enrichment correctly. The highest fuel flow rate I've seen is about 14 gal/hr. Are my injectors actually delivering that? I don't know. After periods of heavier throttle, I do smell that "stinky catalytic converter" smell, so it seems that it is enrichening the mixture over normal.
Any ideas? There are few threads on here about spark knock, so it makes me think it's not "normal" and that I perhaps have a lazy knock sensor. My other vehicle is a 2005 Acura MDX with a very similar engine. That engine never has given us the first bit of knock, so I know these Honda engines CAN be knock-free. I'm just not sure what is normal for the newer engines (my 2009 has the newer J35Z5). Any ideas or comments are appreciated.