I believe the AEM also post processes and conditions it much like ECU+ and won't load down the knock sensor voltage.

 

I tend to disagree with this a bit...actually a lot.

Most of the piggybacks and standalones on the market simply log knock sensor voltage, which is virtually useless. Trying to determine where the knock is simply by looking at knock voltage is a very difficult thing to do.

But, EvoScan doesn't read knock voltage, it reads knock counts, which is something completely different.

Knock counts are the result of many calculations and algorithms that the stock ECU uses to determine what is and what isn't knock. Mitsubishi has spent years and millions of dollars of research with teams of engineers working on this to determine the correct formulas and algorithms to do this.

Now, I understand that these are just formulas and algorithms, but why not take advantage and use what was already done for us. We don't have to know how it is calcuated or what research went into it....all we need to do is log the knock counts. And in my experience with DSMLink for many years, the stock ECU is very good at detecting knock.

And, after all, what we should really care about is when the ECU thinks there is knock anyway, since this is when timing will be pulled and our performance will be affected.

All I am saying is that we finally have a tool that logs 'real' knock as deemed by the ECU, which is what really matters when you are tuning the car. I would suggest that you should believe what EvoScan is logging in terms of knock counts and tune accordingly. When the ECU shows knock counts, you will get timing pulled, whether it is truly knock or not (in my experience aside from phantom knock, the ECU does a pretty damn good job).

Eric

 

I disagree 100%. Every knock count event I have encountered while using EVOScan has coinsided EXACTLY with a reduction in timing. I have 100% complete confidence that EVOScan is telling me when my car is and isn't knocking.

I would agree though that not all knock events are actually detonation/preignition. That I think that is more a result of the factory knock sensors picking up drivetrain noise.

 

Not true, AEM has the ability to filter knock sensor voltage only to record voltage in the range of engine rotation when a spark plug fires.

Ultimately who decides what is real knock and what is noise is the tuner. I trust a skilled tuner whose profession is tuning cars more than a cheap knock sensor.

Those noise signatures are designed for a stock engine. When you modify the engine by changing the cams, intake, exhaust system, clutch, ect that noise signature is different and those factory algorithmns become grossly inaccurate.

This comes directly from MoTeC USA when I went to their training seminar. The motorsports grade knock sensor they use to tune modified engines from bosch runs $80,000. When they build knock sensor signatures for engines, changing components like those listed above requires new signatures.

If you tuned cars in this way they will never reach performance levels on par with the best thats out there. Knowing what is real knock doesn't come from staring at a print out given by a computer program. It comes from pushing the limit on your own car, reading spark plugs, using sound instrumentation, knowing fuel characteristics, using a dyno, and sound judgement that only comes from experience.

In terms of EVOscan, some users have reported discrepancies, so that's where my comment comes from.

 

This is where you and I differ. I have seen some tunes from 'experienced' tuners and they are downright dangerous. The only thing keeping the engine together is the stock knock correction.

I'm not saying to trust the cheap knock sensor. I'm saying to trust the millions of dollars or research that has been done by the Mitsu Engineering team over the years.

I agree with what you are saying about the noise signature changing with different mods, especially of the valvetrain, but the stock ECU does not just use one static knock signature. Mitsu was smart enough to know that the noise of the engine will vary a bit from engine to engine as well as in the same engine due to different conditions and age, etc. The background noise in the knock thresholds/signatures are adjustable by the stock ECU. It's doesn't simply use knock voltage or a certain value of knock voltage and one static map.

Sure you can, unless you call the best an engine that will last a few passes down the track and then need to be rebuilt.

Tuning a car in the way that I described will guarantee the safest, most powerful tune possible. Tuning a car beyond it's limit to the point of detonation may give a bit more power, but the detonation for (1) will begin to pull timing, which will hinder power, and (2) will eventually result in the desctruction of the engine.


I'm not saying that you have to tune your car that way that I tune mine. All I am saying is that the being able to read and log what the stock ECU thinks is knock is a very valuable tool in tuning the stock ECU.


Eric

 

He said skilled tuners.

 

If the stock knock sensor worked as great as you seem to think it does no one would ever blow their EVO motor. However, on the contrary I have seen maps who put a lot of faith in the in the drastically different twin map tuning method, and these are the cars that make the least amount of power, have dynographs that look like EKG's from the hospital, and worse off still blow engines.

I share a very similar method of tuning with another local tuner here who put out more 290-300 mustang whp (350 dynojet whp) on 91 than anyone else out here. Not one of these cars has had a motor failure, these are daily drivers and not weekend warriors.

It is all statistics... if these group of EVOs can make this type of power then any EVO with similar mods should make within 5% of this number safely if their car is mechanically sound.

If you tune a car to 320 whp on 91, and that is the only car in existence using similar mods, then that is when I would be afraid.

That is a parameter that EVOscan simply doesn't log.

 

Additionally, the limits set in the algorithms aren't just determined by engineers, I bet for the most part the final word comes from accountants.

The ECU needs to be dumb'd down for when XYZ person puts 87 octane in the car. Stock Knock Sensor = Mitsubishi CYA sensor

 

EFIxMR,

You are just about agreeing with me with one of your last posts about tunes that blow the engine. That was my whole point about trusting skilled tuners.

I think we partially agree on some points, but I think you are reading past what I am saying. Where did I say anything about the stock knock sensor being good or working great? I am talking about the stock ECU's logic in determining where knock is present. That's my whole point and is the only reason why I posted in the first place.

And I completely agree with you that Mitsu would tune on the safe side. But that has nothing to do with the ability of the algorithm to detect knock. To be on the safe side, they would simply use very conservative knock correction factors and other similar methods.

I personally have tuned stock DSMs for years as well as my friends. I always stayed on the safe side with my GST, but I was well over 400 HP in the stock 2g bottem end. My friend dynoed his stock 2g bottom end at over 550whp. If you know how weak the stock 2g bottem end is, you know how big of an accomplishment this is. Tunes like that would never be possible with even the hint of detonation. Any detonation at those power levels and the motor would let loose in an instant. His tune as well as mine were always tuned for 0 knock as reported by the stock ECU.

I just like tuning on the safe side, and I trust what the stock ECU is telling me about knock. Just because you can get 320 whp on 91 octane gas doesn't mean that it is a great tune and not knocking. Maybe it is a perfect tune with 0 knock, maybe it is a tune with a lot of knock. I'm not saying that you can't tune. All I am saying is that I would rather tune on the safe side of 0 knock reported by the ECU and get the maximum safe power that I can. Just because a car has held up for a while doesn't mean it isn't knocking. Knock gets increasingly important the more HP you make, but in my opinion, I want 0 of it, no matter what HP I am making.


Eric

 

Eric, what's your last name?

 

Anyone remember this quote, "timing measurments are accurate to a 99.999% certainty?" Or this one, "I cant talk about the datalogger being used, but lets just say its very acurate?"

In that case, the original poster was incorrect and the beta release datalogger (EvoScan) was not quite right in the timing values. That alone is a reason to take EvoScan readings (along with everything in the world) with a grain of salt.

Basically, it's worth considering that the EvoScan readings may or may not be totally accurate everytime. However, when it comes to tuning, I'd agree with the camp that says it is better to err on the side of caution.

 

I agree with you 1000000%. I would add that any electric/electronic monitoring of knock is suspect. The best way to monitor knock is to listen to it with a hearing aide or det can especially on modified cars where the knock sensor picks up all sorts of noise which is NOT knock.

 

I found something funny. My SAFC-II's knock counts and evoscan knocksum correlates very nicely. After all, SAFC's knock detection feature wasn't that bad.

 

I find these statements to be contradictory. Not trying to flame but these statements are saying two different things.

In terms of my history, I tune competition drag and open track hondas professionally, my quickest and fastest customer has run 10.3 @ over 140 in SFWD trim. He also owns a wally, and is listed in www.fastestfwdstreetcars.com. A number of my other customers are also listed in the top 20 of www.urbanracers.com SFWD list.

On the subject of fragile engines my record on the stock b18C GSR DOHC vtec is 395 whp. That car in quick 8 competition ran multiple 10.7's @ over 130 mph and ended up with the top eliminator trophy.

The time attack EVO I tuned made 404 Mustang whp and went to multiple events without engine failure. This car had no knock sensor whatsoever and was tuned on Autronic.

So now that we established that we can both tune cars lets get back to subject.

You missed the point of what I was saying. I would never tune a car to 320 whp on 91 if the estabilished average for the vehicles with the same mods is 300 whp.

My EVO has over 39,000 miles and made 375 Mustang whp (425-435 dynojet whp) on 91 pump.

Problem is... if you are relying on the knock sensor you really don't know if the engine is knocking or not. I dont want any knock either.

The judgement call on what is real knock and what is noise, depends on all tuning factors... Not by looking at some kind of computer program.

It comes down to is...

at what rpm range knock is reported by the ECU
how many psi
what duration the cam
what octane the fuel
what compression the engine
what heat range the plug
what size the exhaust system
cat or no cat
how far the current tune is from Maximum Brake Torque
what are the established averages
what temp is the AIT
what temp is the ET
what is the engine mileage
are there deposit on the porcelain of the plug
what color is the porcelain
where is the heat mark on the ground strap of the plug
approximation of exhaust backpressure from established knowledge
ect...

 

To add to that...

In norcal and socal the highest whp cars were actually achieved with the stock ecu rom, SAFC, and 720's ...

That isn't by coincidence. And from my understanding the cars still run fine to this day.