PaleRider

Seems to me the ECU should feed back and reduce timing or boost or both if knock is senced...is this the case? If it is not, why not? If not wouldn't you be worried about getting some bad gas and blowing up your engine?

Do the ECU reflashes like cobb ect disable the normal feedback and leave you more at risk...is that where the benefit in custom tuning comes from (living dangerously)? Is this the reason for all the aftermarket guages and stuff to warn you so you can change maps or take some corrective measure such as inject meth / water to retard pre detonation if needed (although it probably isn't normally used as a safeguard, probably to again strech the limits)?

How much of this stuff is already bulit in and if not enough what is recommended...

Why wouldn't knock sencing be more important than wide band air fuel...mostly I see wide band air fuel feedbacks advertized.

lot of questions...trying not to learn the hard way (like I normally do)

Panda_stunter

iTrader: (1)

Theoretically, stock tune does that. If there's knock, ecu will pull timing to get rid of knock. But it's a reactive condition. Knock on 3500rpm, pull timing on 3750rpm. At least that's what the ecu does.

Now, tuners can do this as well, let the reactive ecu conditions to take care of the knock, but they won't. Instead, they will get rid of knock at the base of the knock and nip it before it even starts. That what u call active tuning. Instead of 3500rpm knock, they will pull timing at 3500rpm to get rid of that knock in the first place.

Stock tune is at 10.5 afr across the board. What tuners do is lean that out, iron out the knocks and get u more power. Just leaning out ur afr will give u power, but tuners also change out many things. MAF scaling, if u have a different intake which most likely u do. Mivec tables, ignition tables, MAF vs map tables, wg cycles....a lot. I could list everything that they change for u, but I'm lazy to type out everything. But trust me when I say the amount of money u pay a tuner is cheap. But also, don't go to any tuner that says they can tune. Get someone that has a good track record on the forums.

The amount of time and knowledge tuners give to u when they tune ur car took a lot of time and experience.

I have great appreciation to the tuners since I'm tuning my car myself, and it's been a loooooong road for me.

PaleRider

Quote:

Originally Posted by Panda_stunter

Theoretically, stock tune does that. Ifthere's knock, ecu will pull timing to get rid of knock. But it's a reactivecondition. Knock on 3500rpm, pull timing on 3750rpm. At least that's what theecu does.

Thanks, Panda_stunter

...if the tuner does agrand job of riding the knifes edge isn't that just for that particular condition where the map was constructed? wouldn't you be much better off with something that adapts fuel quality, fuel pressure,temperature, humidity, ...which all culminates into a problem of predetonation right?...seems to me the ideal thing would be to set up your tuning for optimum conditions and then have a knock sensor kick in some meth\water injection to bump you out of that bad spot, that would be a reactionary response, and the closed loop response time would need to be rapid no doubt. It hink this is what I’m going to do once i get more mods in place and have more at risk.

Seems some tuner outfit would like to have some method to determine gas quality, temp, atmospheric pressure, etc and trigger map selection accordingly thus enabling slim to none margin from max tune.

Knock (significant amount) is sensed,meth/H2O is injected, Fuel quality and other factors are re –analyzed andappropriate map is reflashed

Windstorm

The ECU already responds to some of the variables you listed. Tuning doesn't change this, it just optimizes everything.

Would be nice to have a fuel quality sensor though.

Panda_stunter

iTrader: (1)

No, they change out more parameters than u would think. Even ur idle.

Quote:

wouldn't you be much better off with something that adapts fuel quality, fuel pressure,temperature, humidity, ...which all culminates into a problem of predetonation right?...

Unfortunately, even ecu can't track these changes unless u have the correct sensors...which factory doesn't even have. Tuners can only work with what they have or what is readily available.

Quote:

seems to me the ideal thing would be to set up your tuning for optimum conditions and then have a knock sensor kick in some meth\water injection to bump you out of that bad spot, that would be a reactionary response, and the closed loop response time would need to be rapid no doubt. It hink this is what I’m going to do once i get more mods in place and have more at risk.

They already do that. When u get a custom tune, and if the tuner is competent at what he does, ur knock sensor won't even kick in at all.

competent tuners already do all that.

PaleRider

yeah, seems to be the thing left hanging out there. I you got some bad gas (tune or not) the normal instruments, boost and air fuel would read just fine but the engine would be very unhappy...I wonder how rare the chance is that you get lower than advertized octaine gas?

I just installed a cobb tune on my stock X...man what a difference! almost shocking...cant wait to install my new catback and airfilter..feeling good about my


Next mods for me will be the down pipe, high flow cat and wide band sensor. with the wide band sensor i can get back on topic and get something like the AEM guage that reads both boost and air fuel on the same guage and you can set the alarm trigger that outputs a voltage or ground or something (in the case of overboost or too lean) such that you can use it to do something about your condition....like trigger the waste gate to open or change to a conserative map or in my case maybe rig it to activate a meth injection.

still wonder about the bad gas sanerio tho...does anybody make a knock guage with a settable knock tollerance trigger output, like the AEM does with boost and AFM?

Panda_stunter

iTrader: (1)

There is a gadget that tests ethanol and tells u what grade the ethanol really is. I'm not sure if there's one for pump gas.

Just so u know, X ecu already switches maps when low grade fuel is used. If u look into the stock tune, there is the high octane fuel map and low octane fuel map. If ur fuel is really what it is, 93 or 91 here in the west coast, then it would use the high octane fuel map, but when it detects knock caused by fuel, it will switch to low octane fuel map instantaneously. It will revert back to high octane when it doesn't detect anymore knocks.

The evo ecu is more complex than u think. If u can think of it, the engineers that made the car already thought of it too. That's why the evo is a formidable car. Even stock tune has 2 maps already.

PaleRider

Very cool, thanks for all the info...what a great forum.

I'll go worry about other things now like how to afford all the mods I have in mind

Panda_stunter

iTrader: (1)

First week of owning the evo, I already have full tbe, intake and uicp....now im going into the engine and get cams.

Windstorm

don't know about a gauge.. I use tephramod knock cel, but it's not avail for your 2013 unfortunately.
and yes, the odd tank of gas will give noticeably more knocks. (even from the same gas station). Once you're constantly looking at it, it becomes easy to spot. So quality variations definitely happen.

PaleRider

Dude...you are my new hero! Brand new one?

PaleRider

yep, thanks windstorm...I'm logging now via cobb and can monitor cel count and will figure out the logistics of checking each new tank....did notice i get cel counts when hitting the rev limiter, is this real or a misdiagnostic experience?

Werdna06

iTrader: (1)

bump this one, i have experienced this too and would like so info if available. thanks.