H22A all-motor build : Knock Sensor - A good or bad thing? - Honda Prelude Forum

Mike95lude · 03-24-2004, 11:55 PM

I have an all-motor build nearing completion with JDM Type-S pistons, 11:1 compression . I'll also likely mill the head some to bump compression a little more. Haven't decided yet on what I want to shoot for, but it will be less than 12:1 for sure. Also, I will be removing the balance shafts, which will cause more engine vibrations, could this trip the knock sensor to detect false knock?

I will be able to extensively road and dyno tune the vehicle with Hondata. I already have a p28 ecu that I figured I would use. I don't need the secondaries because I'm using the Euro-R intake manifold. But this car is my daily driver and I need the motor to last. It will run on 92 octane. So would it be a good idea to use a p30 or p72 ecu instead and have knock sensor capability? Or use an aftermarket knock system like J&S?

Another potential issue I'm wondering about is if using a p72 or p30 ecu will it even be able to properly detect knock on an H'series motor anyway? I mean the ECU would be designed to pick up knock on a 1.6 or 1.8 B'series engine. Or would it still work properly?

Thanks -Mike

ludevtec · 03-25-2004, 09:28 AM

hmmm very good questions. I am interested tosee what people say because I am going to use a p28 with hondata on my h23vtec. So I would like to know also.

I have always thought that if your tuned with a good AF ratio that your motor shouldnt knock anyway. So if you are confident in your tuning capabilities I would say that the knock sensor will hurt the pereformance a little.

Daemione · 03-25-2004, 09:32 AM

I would say eliminate it - with that many variables changing on the engine, it's probable that the stock knock sensor will be easily confused.

But for tuning purposes, I think you'd want something rigged up, especially if you're street tuning. A J&S would be ideal, of course, but check out this page - a DIY knock detector for about $15. Obviously not any good as a permanent knock prevention system, but would be handy for tuning.

Satan_SRV · 03-25-2004, 03:29 PM

vibrations from a lack of balancer shafts is not the same harmonic as detonation/knocking. I wouldn't worry about it, many people have done this already.

Mike95lude · 03-25-2004, 04:42 PM

Ok, I didn't really think that would be an issue anyway, but the main issue I'm looking for opinions on is whether or not I should use a p28 ecu that has no knock sensor capability. Or should I get a different ECU? and Why? Basically, is the knock sensor a good or bad thing in an allmotor build when switching from the factory p13 ecu? (as the topic title says)

Satan_SRV · 03-25-2004, 08:42 PM

Are you going to be using a hondata system? I don't know why else you would be going with a different ecu...

If so good tuning with the hondata and a wideboand O2 the knock sensor should be necessary.

Mike95lude · 03-25-2004, 09:18 PM

Quote:

Originally posted by Satan_SRV
Are you going to be using a hondata system? I don't know why else you would be going with a different ecu...

If so good tuning with the hondata and a wideboand O2 the knock sensor should be necessary.

Should or Shouldn't be necessary? Yeah I will be using Hondata or Uberdata. So with a p72 or p30 ecu the knock sensor will function optimally even though an H22A engine is being used? I mean the if the ECU is tuned to pickup the knock from a B'series engine, will make it less effective/ineffective at accurately detected H'series knock? See what I'm saying.

alphajesse · 03-26-2004, 01:52 AM

My experience is that a p72 picks up all sorts of false knock around VTEC engagement on a h22.
You can feel a huge difference back to back with the sensor enabled/disabled.

I've heard from a reliable source that all the knock boards are compatable with all the knock sensing ECUs, so take the one out of your p13 and put it on the p72 for proper knock sensing.

Mike95lude · 03-26-2004, 01:03 PM

Quote:

Originally posted by alphajesse
My experience is that a p72 picks up all sorts of false knock around VTEC engagement on a h22.
You can feel a huge difference back to back with the sensor enabled/disabled.

I've heard from a reliable source that all the knock boards are compatable with all the knock sensing ECUs, so take the one out of your p13 and put it on the p72 for proper knock sensing.

Damn thats a great idea. How hard would that be? Can you just pull the chip out? Thanks for the useful advice.

alphajesse · 03-27-2004, 12:25 AM

The knock board is a seperate daughterboard inside the ECU. It is attached with a ribbon cable. It is basically a straight swap.

If you compare the two knock boards, I've also heard that you can make one into the other by changing configuration resistors.
Just take a look at both boards, and add/remove components till they are the same. This is true of p30 and p72 and p14 knock boards, p13 will probably work too.
Search around on PGMFI.org, you can find some decent info on it.