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Arouse the DAMPFHAMMER!
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My understanding is that the knock sensor is tuned to a specific engine so it only picks up the specific frequencies that indicate knocking rather than all noise and vibration to prevent false trips from normal engine vibration, road vibration, rattles, etc.
Sometimes yes. Especially the simple knock sensing systems like the Honda, which doesn't do any high sophisticated filtering of frequencies by ECU HW and SW. There the resonance frequency of the Sensor is important. In the OEM industry today you look more into getting a standard sensor for cheap and do the right filtering via SW and HW in the ECU to get the knock signals extracted from engine noise. For example the weight of the mass, which is used for sensing the acceleration detection is a major factor for such systems, as it influences e.g. the signal-noise ratio of the sensor itself.
 

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Discussion Starter #43
Sometimes yes. Especially the simple knock sensing systems like the Honda, which doesn't do any high sophisticated filtering of frequencies by ECU HW and SW. There the resonance frequency of the Sensor is important. In the OEM industry today you look more into getting a standard sensor for cheap and do the right filtering via SW and HW in the ECU to get the knock signals extracted from engine noise. For example the weight of the mass, which is used for sensing the acceleration detection is a major factor for such systems, as it influences e.g. the signal-noise ratio of the sensor itself.
Cool, thank you for the information. I never thought about the possibility of the ECU filtering the noise, but that makes perfect sense. Since Honda ECUs don't do much noise filtering, I am thinking if anything it may be better to save the money for the sensor and just change the plug since there is a possibility that the sensor is tuned to the specific engine.
 

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Arouse the DAMPFHAMMER!
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Cool, thank you for the information. I never thought about the possibility of the ECU filtering the noise, but that makes perfect sense. Since Honda ECUs don't do much noise filtering, I am thinking if anything it may be better to save the money for the sensor and just change the plug since there is a possibility that the sensor is tuned to the specific engine.
I worked 9 years in an gas engine development department. For those engine we used just stock Bosch sensors - one per cylinder (up to 20 cylinders per engine) - and had own control device which filters the sensor signal by a more complex Laplace transformation. But there is a message, non of the OEM's, not a single one has a reliable system which detects every knock correctly in intensity and time. Especially the pre-ignition events, e.g. on those down sized engines and highly boosted engines with emission and efficiency related ign. timings, are hard to detect. I saw knock events on the cylinder pressure indication systems creating cylinder pressure of 300+ bar and the knock sensor didn't here anything because it was no knock resonance in the chamber, just an amazing fast combustion. Therefore our latest engine design includes cylinder pressure indication as a series system for fuel, combustion and knock control on that marine applications. That is the only way to detect any irregular combustion event which endangers the engine healthiness. But it is exceptional expensive.
 

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Discussion Starter #45
I worked 9 years in an gas engine development department. For those engine we used just stock Bosch sensors - one per cylinder (up to 20 cylinders per engine) - and had own control device which filters the sensor signal by a more complex Laplace transformation. But there is a message, non of the OEM's, not a single one has a reliable system which detects every knock correctly in intensity and time. Especially the pre-ignition events, e.g. on those down sized engines and highly boosted engines with emission and efficiency related ign. timings, are hard to detect. I saw knock events on the cylinder pressure indication systems creating cylinder pressure of 300+ bar and the knock sensor didn't here anything because it was no knock resonance in the chamber, just an amazing fast combustion. Therefore our latest engine design includes cylinder pressure indication as a series system for fuel, combustion and knock control on that marine applications. That is the only way to detect any irregular combustion event which endangers the engine healthiness. But it is exceptional expensive.
Wow very interesting, thank you for sharing! Makes sense that knock sensors don't always detect knock accurately, never thought too much about it. I have also heard that they can sometimes pick up normal engine and road vibration and things like exhaust rattles as knocks. How true is that? Thanks
 

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Arouse the DAMPFHAMMER!
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...I have also heard that they can sometimes pick up normal engine and road vibration and things like exhaust rattles as knocks. How true is that? Thanks
That's correct. There e.g. are well known aftermarket cams which creates a noise which the Honda OEM ECU takes as knock. With those cams you have to switch of the stock Honda Knock system, otherwise you collect 100's of knocks per minute and the ECU runs up to 12° ign. retard just because of a engine noise, which is definitely not a knock. For me as remote tuner something I have always to investigate what is knock and what are modified engine parts. Can be pretty challenging.
 

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Discussion Starter #47
That's correct. There e.g. are well known aftermarket cams which creates a noise which the Honda OEM ECU takes as knock. With those cams you have to switch of the stock Honda Knock system, otherwise you collect 100's of knocks per minute and the ECU runs up to 12° ign. retard just because of a engine noise, which is definitely not a knock. For me as remote tuner something I have always to investigate what is knock and what are modified engine parts. Can be pretty challenging.
Wow I had no idea aftermarket cams could do that, very interesting. Yet another good reason to keep the K24 stock :) The only mod it has is a Type S oil pump, so hopefully I don't have any issues with false knocks.

Another question. I have a base model K20 ECU that a buddy gave me from a Honda Stepwagon. Would that ECU be safe to use for startup and gentle driving until I can afford to get Kpro since it was free and has no immobilizer? I know about the differences, I just need to get by for now. The pinout is the same. I can't use a TSX ECU because it is set up for an electronic throttle body. Thanks
 

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Wow I had no idea aftermarket cams could do that, very interesting. Yet another good reason to keep the K24 stock :) The only mod it has is a Type S oil pump, so hopefully I don't have any issues with false knocks.

Another question. I have a base model K20 ECU that a buddy gave me from a Honda Stepwagon. Would that ECU be safe to use for startup and gentle driving until I can afford to get Kpro since it was free and has no immobilizer? I know about the differences, I just need to get by for now. The pinout is the same. I can't use a TSX ECU because it is set up for an electronic throttle body. Thanks
At part throttle it should be fine, although I’m sure it will be running lean. The ecu should correct the fuel to a certain amount , but as to how much I’m not sure. If the o2 is reading correctly I would think it’s “ok”
 

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At part throttle it should be fine, although I’m sure it will be running lean. The ecu should correct the fuel to a certain amount , but as to how much I’m not sure. If the o2 is reading correctly I would think it’s “ok”
That's what I was thinking, thank you for confirming. I will probably leave the VTEC solenoid unplugged though since the base model K20 has VTEC-E that comes on at 2500 RPM or something and I don't want to be cruising in VTEC all the time.
 

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That's what I was thinking, thank you for confirming. I will probably leave the VTEC solenoid unplugged though since the base model K20 has VTEC-E that comes on at 2500 RPM or something and I don't want to be cruising in VTEC all the time.
Ya that’s a good idea, I wonder if turning the fuel pressure up a bit would help as well , while it’s on the 2.0 ecu.
 

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Discussion Starter #53
Almost half a liter displacement is a pretty good jump as far as fuel is concerned. @LotusElise may have further knowledge on this.
It is but since I believe my K24 has bigger fuel injectors than the base model K20 that should help somewhat. And whatever remaining difference there is I think the fuel trim should correct it reasonably well. It doesn't need to be fast or run perfectly for now, it just needs to run well enough that I can drive it and not damage anything, which I don't think it will since I won't be beating on it until I get a proper ECU. I don't have the money to get Kpro now since I still need to buy quite a few other parts for the swap, but once it is in the car and driving I will get Kpro as soon as I can afford to.

Once I get Kpro will the TSX base map be good enough for it to run decent and safely or will I still need a tune? My engine is totally stock besides the Type S oil pump, only thing that will be aftermarket is I will need to get a different header and exhaust for the swap and possibly a custom cold air intake. Thanks
 

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It is but since I believe my K24 has bigger fuel injectors than the base model K20 that should help somewhat. And whatever remaining difference there is I think the fuel trim should correct it reasonably well. It doesn't need to be fast or run perfectly for now, it just needs to run well enough that I can drive it and not damage anything, which I don't think it will since I won't be beating on it until I get a proper ECU. I don't have the money to get Kpro now since I still need to buy quite a few other parts for the swap, but once it is in the car and driving I will get Kpro as soon as I can afford to.

Once I get Kpro will the TSX base map be good enough for it to run decent and safely or will I still need a tune? My engine is totally stock besides the Type S oil pump, only thing that will be aftermarket is I will need to get a different header and exhaust for the swap and possibly a custom cold air intake. Thanks
A lot of guys just use a calibration they find on the kpro list. It won’t run perfect but it will get close if you choose the right one and can make minor adjustments. On my k24a I have no internal changes just the rbc /70mm tb and RCREW header. I used a tsx cal with hytech header and cai and it will correct at idle to 14.6:1 but as soon as I rev it up it goes lean as hell like 19:1 +.I took it around the block lightly and it “felt fine”. I believe that was with 3-4% overall fuel trim added as well. So it will run on a stock map but without a tune , not properly in my opinion.
 

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Discussion Starter #55
A lot of guys just use a calibration they find on the kpro list. It won’t run perfect but it will get close if you choose the right one and can make minor adjustments. On my k24a I have no internal changes just the rbc /70mm tb and RCREW header. I used a tsx cal with hytech header and cai and it will correct at idle to 14.6:1 but as soon as I rev it up it goes lean as hell like 19:1 +.I took it around the block lightly and it “felt fine”. I believe that was with 3-4% overall fuel trim added as well. So it will run on a stock map but without a tune , not properly in my opinion.
Well that's not the answer I was hoping for but thanks for your help. Doesn't the TSX base map basically work like a stock TSX ECU? Sorry for my ignorance, I unfortunately never had an aftermarket ECU to mess with and I never did any swaps that required anything other than an OEM ECU, so I am still new to the ECU tuning thing. For a while I was thinking about getting AEM EMS since I could use it with my D17 now and use it when I put the K24 in, but Kpro looks like a better option for my goals since I am new to tuning and it retains all the stock functionality like AC, immobilizer, and OBD functionality.
 

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Arouse the DAMPFHAMMER!
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I will probably leave the VTEC solenoid unplugged though since the base model K20 has VTEC-E that comes on at 2500 RPM or something and I don't want to be cruising in VTEC all the time.
If you unplug the VTEC solenoid your engine will run overly rich and maybe the ECU fuel altering walks out of the maximum allowed range. I wouldn't do it that way.

Almost half a liter displacement is a pretty good jump as far as fuel is concerned. @LotusElise may have further knowledge on this.
In a first order assumption you need about 14 % fuel everywhere. One can do that by adding in the fuel map or by increasing fuel pressure accordingly.

It is but since I believe my K24 has bigger fuel injectors than the base model K20 that should help somewhat. And whatever remaining difference there is I think the fuel trim should correct it reasonably well. It doesn't need to be fast or run perfectly for now, it just needs to run well enough that I can drive it and not damage anything...
The K24A2 injector has the same size as a K20A2, which is 310 [email protected] bar. The K20A3 has 270 [email protected] bar injectors. So for the same injection window you get roughly 17 % more fuel with the 310's, so would be on the rich side.

Maybe I lost it, what exactly is the setup of before and after?
 

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Discussion Starter #57
If you unplug the VTEC solenoid your engine will run overly rich and maybe the ECU fuel altering walks out of the maximum allowed range. I wouldn't do it that way.

In a first order assumption you need about 14 % fuel everywhere. One can do that by adding in the fuel map or by increasing fuel pressure accordingly.

The K24A2 injector has the same size as a K20A2, which is 310 [email protected] bar. The K20A3 has 270 [email protected] bar injectors. So for the same injection window you get roughly 17 % more fuel with the 310's, so would be on the rich side.

Maybe I lost it, what exactly is the setup of before and after?
Cool, thank you for the information. Wouldn't leaving the VTEC solenoid plugged in and running in VTEC basically all the time be problematic? I would think it would be for several reasons such as timing being off and possibly not enough oil pressure to correctly activate real VTEC at such a low RPM or possibly even dropping the oil pressure too much, but I could be wrong.

Thanks for confirming what I thought about the injector size. That doesn't seem like a big enough difference to be a problem, fuel trim is frequently more than 3% off with no problems. Also better to be a little rich than lean. So I may actually be better off with the base model K20 ECU for now than a Type S or Type R ECU due to the injector size difference.

What about ignition timing? Since my K24 has higher compression than the base model K20, could the ignition timing possibly be advanced enough to be problematic?

My setup is a JDM K24A (equivalent to US K24A2 06-08 Acura TSX engine) going into my ES1 Civic. The engine is totally stock except for a Type S oil pump and an 08 TSX intake cam (bigger than the 04-05 cam used in the JDM K24A's.
 

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Discussion Starter #58
The EP3 harness just got here. I am going to clean it up a bit and repin the C101 connector before I put it on the engine for good, but for now I laid it over the engine how it normally sits and it seems to work perfectly. All the connectors are the same except for the crank sensor and everything reaches except for the coolant temp sensor. I have read that some things need to be extended since the K24 is taller than the K20, but so far that does not seem to be the case except for the temp sensor, which is an easy fix to extend 2 wires.

Also, the TSX charge harness that came with the motor doesn't plug into the EP3 engine harness because they both have male plugs. However, I don't think I need one. I am going to run my own power cables for the alternator, starter, and fusebox, so that's not a concern. That basically only leaves the starter signal wire, knock sensor wire, and the 4 wires for the green alternator plug, which won't be a big deal to run manually. I'll run 6 wires manually any day to save the $100+ that a charge harness costs!
 

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The EP3 harness just got here. I am going to clean it up a bit and repin the C101 connector before I put it on the engine for good, but for now I laid it over the engine how it normally sits and it seems to work perfectly. All the connectors are the same except for the crank sensor and everything reaches except for the coolant temp sensor. I have read that some things need to be extended since the K24 is taller than the K20, but so far that does not seem to be the case except for the temp sensor, which is an easy fix to extend 2 wires.

Also, the TSX charge harness that came with the motor doesn't plug into the EP3 engine harness because they both have male plugs. However, I don't think I need one. I am going to run my own power cables for the alternator, starter, and fusebox, so that's not a concern. That basically only leaves the starter signal wire, knock sensor wire, and the 4 wires for the green alternator plug, which won't be a big deal to run manually. I'll run 6 wires manually any day to save the $100+ that a charge harness costs!
If you cut just the loom by the coolant temp sensor wiring where it joins the harness, it will reach the side of the head without having to extend the wires. And I had the same problem with the charge harness plugs, I used a 99-00 civic distributor plug and it fit right up. Just my .02. Glad to hear you made some progress and got your wiring 👍 some purple power in a cup with an old toothbrush cleans the plugs up almost brand new.
 

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If you cut just the loom by the coolant temp sensor wiring where it joins the harness, it will reach the side of the head without having to extend the wires. And I had the same problem with the charge harness plugs, I used a 99-00 civic distributor plug and it fit right up. Just my .02. Glad to hear you made some progress and got your wiring 👍 some purple power in a cup with an old toothbrush cleans the plugs up almost brand new.
Great tip, thank you! I will take a look at that tomorrow. I don't think I really need a plug for the charge harness, I think if I just solder the needed wires to it that should be alright, I don't see why I would need to unplug it again. Good tip to use Purple Power, I used a spray bottle full of alcohol, a toothbrush, and paper towels and that seemed to work pretty well for cleaning up the connectors. I'd be careful using any corrosive chemicals like Purple Power on the connectors, if any remains in the connector or gets into the wiring that may cause problems in the future. This car is my daily driver and it's far from perfect anyways so I am not going for show car perfect here, but I wanted it to be reasonably clean initially even though it won't stay that way.
 
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