"Tuning by knock is for amateurs"

[soldave]

Was doing some tuning on my car yesterday with a friend of mine, and we were having a few issues with knock (as you might have seen in one of my other threads). We joked a little about just taking the knock sensor out and running without one (or, more seriously, using something like an MSD Engine Knock Alert). Friend said that a couple of respected tuners here in Okinawa believe that tuning by knock is a relatively amateurish way of tuning, and removing/disabling the knock sensor is how they would tune cars a lot of the time.

I kind of understood this, but if they disable the knock sensor, what do they use for tuning? Do they just go by timing, air: fuel ratios and EGTs?

Sorry if this is a very simple question, but I'm a very simple person!

 

[JeffGST]

Foolish to say the least.

The knock sensor is there to alert you of engine knock that the sensor picks up. The ECU is sent this information and retards the appropriate amount timing away to help fend off the detenation.

Removing this safety feature is motor suicide. There is no benefit from disabling the knock sensor.

I do not tune cars based solely on the knock sensor data, but a combination of quality of fuel, AFR, Timing and current conditions. The KS is there to provide me with detention data. It also let me know where a particular engine like to be at. Some motors like to have richer AFR's than other, some like more ignition advance than others.

As I said before, professional tuners do not SOLELY tune for no knock, but they still use the valuable knock sensor info to adjust AFR and timing parameter. Use it as extra data, do not ignore it.

 

[soldave]

Well they are the pros and know more than me. I'm sure if they'd had problems doing it the way they do, they wouldn't have done it.

I think quite a few of the pro tuning shops in mainland Japan and in the UK tune that way too - the ones who do the real performance tunes.

 

[AlaskanDsm]

well if you think that they are the pros and thats what they do and you choose to follow it...just be warned if your engine decides to leave you with a heap of metal!! I agree with jeffgst. Don't ignore the knock sensor but you should at least keep it in mind. How else would you know if your engine was about to blow up on you...personally I don't want to have to do a 3rd rebuild on my car in a years time!!

 

[soldave]

well if you think that they are the pros and thats what they do and you choose to follow it...just be warned if your engine decides to leave you with a heap of metal!! I agree with jeffgst. Don't ignore the knock sensor but you should at least keep it in mind. How else would you know if your engine was about to blow up on you...personally I don't want to have to do a 3rd rebuild on my car in a years time!!

I wouldn't disregard it completely if I personally went down this route, but it wouldn't be the be-all and end-all when it comes to timing retardation.

And you've done 2 rebuilds on a car in the past year? Is that because you didn't use a knock sensor?

 

[JeffGST]

Well they are the pros and know more than me. I'm sure if they'd had problems doing it the way they do, they wouldn't have done it.

I think quite a few of the pro tuning shops in mainland Japan and in the UK tune that way too - the ones who do the real performance tunes.

What are the pros of disabling and ignoring the knock sensor? The only one I can think of, is that you will not get any timing retard from the ECU. So if you tuned the car at 20 degrees of timing at WOT, then you will get 20 degrees of timing at WOT everytime. But there is no knock sensor ECU controlled timing retard, just in case something were to happen.

Clogged Fuel Filter, Alternator voltage drops, Higher temperature changes, Sudden changes in fuel quality are just a few thing I can think of that can affect detonation.

The fact is that a motor produces the most power just when it starts to knock. This is tuning to the limit, because you are right at the knock threshold. The biggest problem is that your margin of error is reduced to nothing when you are right at this point. You make the most power WITH THE MOST RISK.

I like some breathing room.

 

[1992awdlaser]

Jeff knows what he is talking about and you should listen to anything he has to say.

The only reason I have heard of anybody removing the knock sensor is that they were getting knock that they couldn't get rid of(probably because they didn't know what they were doing). Since they were knocking it was limiting their power. So now since the knock sensor is out of the equation the ecu sees no knock which creates more power. To do that is stupid. Find out why it is knocking and fix the problem.

 

[soldave]

Jeff knows what he is talking about and you should listen to anything he has to say.

The only reason I have heard of anybody removing the knock sensor is that they were getting knock that they couldn't get rid of(probably because they didn't know what they were doing). Since they were knocking it was limiting their power. So now since the knock sensor is out of the equation the ecu sees no knock which creates more power. To do that is stupid. Find out why it is knocking and fix the problem.

You've not heard of people getting engine noise that is not actually knock but that is being detected by the knock sensor and so retarding timing when it shouldn't be. That's not happening in my situation but I have known of it to happen.

 

[1992awdlaser]

Yes I have heard of that which can also be fixed in every case I have seen. The two main ones that come to mind are stock motor mounts that let the engine move too much and the carrier bearing on the driveshaft being loose.

 

[turboglenn]

I ran for 8-9 years with no knock sensor, i blew one motor during this time due to a faulty wideband i was tuning with at the track. I've owned the MSD knock box and it's junk compared to the J&S safeguard knock unit, i would almost rather have the "knock box" listening device over the MSD unit anyday. I've never seen the knock box in real life, but from my experience, the MSD unit only seems to tell you there's knock once it gets pretty bad. The MSD unit is more of a "last ditch effort" type of thing only catching the problem after it's hit hard enough to start doing damage. The J&S picks it up at the onset and solves it fast.

THere's always going to be a big 2 sided debate about tuning by knock sensor VS. tuning from experience and the feel of and listening to the motor. My maps both ways only vary by 2* of timing with the same AFR and this motor has been running at least 5 years without a knock sensor. I only used the MSD knock box on the dyno, and since it took a crap on me at my last dyno session i bought a J&S safeguard and installed it to run full time in the car, and the only thing i can say about this module is, it's just amazing!

You would be surprised how well this unit does with distinguishing knock from other sounds. And it's ability to only pull the timing in the cylinders that need it leaving all the other cylinders with full timing to keep making power should you choose to stay into it. Which is another thing the J&S does, you can run while it's pulling 5-8 degrees and not have to let out, there's FSAE cars and formula ford series cars that just crank their timing and rely on the J&S to build the timing curve for the motor and keep it running on the ragged edge of performance while not blowing up, as everythign else is so closely matched on these cars they have to rely on any little trick they can to make the best power as much and as long as possible.. I mean these people weigh their cars by the gram, talk about overkill!

One of the main reasons i went stand alone was becasue of the hyper active mitsu knock sensor and having to tune around it, so i wouldn't say that either way is foolish, but tuning without one is best left to people with more tuning experience since things can go drasitically wrong real fast without one. That and most people don't know how to spot knock from the look of the exhaust, or distinguishing knock from a miss or stutter and usually by the time you begin to pick it up the old fashion ways, the motor has been detonating for a good bit already. So tuning without one is a little trickier, but i wouldn't say foolish. I've tested theJ&S unit on my mitsubishi by cranking my timing on a low boost run, counting how many degrees it pulled out and removing exactly that amount of timing from the map, and honestly i've got the best timing map i've ever had! I did this all the way to 17psi without any issues, but have been too stubborn and scared to do it up in the 25+psi range. Although there's a huge following for this unit in the mustang world where they're just letting this box build the timing map for their supercharged cars running a factory ECU with some piggyback fuel management, these are the guys NOT blowing head gaskets once a week . SO you CAN rely on a knock sensor to save your motor and help you set timing limits, but i wouldn't rely heavily on the mitsubishi unit telling you the truth all the time. I love my J&S, and the only way i'd end up using the mitsu sensor again is either through the AEM EMS or some other management that has filtering abilities to appply to the knock signal.

Honestly there was a time years ago that i hated all knock sensors and believed almost the same as you said the japanese do when it comes to "tuning to please the knock sensor" But anymore i am a believer that a knock sensor is just another tool to make tuning easier, you just need a quality unit and the experience to know if it's "acting up". The mitsubishi unit dissapoints me everytime i have to tune to please it, but DSMlink seems to be the ticket for cars that are running the factory sensor and still want a good tune out of their car, the more i get to play with these units the more i wish it had been around 10 years ago when i started ripping the wires out of my car and putting in the haltech, i love my ECU, but there's something to be said for the simplicity of DSMlink.

 

[JeffGST]

You've not heard of people getting engine noise that is not actually knock but that is being detected by the knock sensor and so retarding timing when it shouldn't be. That's not happening in my situation but I have known of it to happen.

Of course. It is called "phantom knock" but that only occurs during vacuum conditions.

You state in your other thread that you don't have any means to retard timing at any given RPM point. The only control over timing you have is retarding timing at the CAS. I can't believe any reputable shop would tune this way, unless you gave them the OK to do it.

You need a quality engine management before you complain about knock being falsely heard by the ECU. The Evo I timing map is just as aggressive as the 1G timing map. It has it's highs right around 5500 and peaks at 6000. And from the looks of your logs, you are knocking right at that point.

You knock at peak timing, and you are going to push that data to the side and just claim it to be false because you can't get rid of it? WTF Tuning with an AFC is great for adjusting airflow, but horrible for timing control since it hides airflow away. Invest in a EM.

 

[soldave]

You knock at peak timing, and you are going to push that data to the side and just claim it to be false because you can't get rid of it? WTF Tuning with an AFC is great for adjusting airflow, but horrible for timing control since it hides airflow away. Invest in a EM.

You probably need to check up on my other thread as I've written more on that over the weekend, and am not claiming the knock is false any more.

turboglenn - very nice comments there. I have looked at the J&M and MSD actually. J&M does look like a very nice piece of kit even thought it's a little on the pricey side.