ECU Tuning Parameters for higher performance 3

[lurks]

I have been researching performance modifications for a 4 cylinder turbo car and had a question about tuning. When you purchase a "canned" tune to flash to your ecu what parameters are changed? My understanding of a vehicle's ecu is that it is a closed loop system that will automatically search for stoich air/fuel ratio. Is there something that I'm missing?

Thanks in advance,

lurks

 

[SomptingGuy]

Imagine the pride you'd feel being one of the Harley OEM exhaust designers. Their designs never wear out.

- Steve

 

[dgallup]

Matt

I'm sure the major automotive OE's do a splendid job of mapping to the nth degree. But I have ridden many a motorcycle with poor factory mapping. It seems to endemic with companies that are new to fuel injection. Once they have released about their 10th model they seem to get most of the bugs out. We sell fuel injection equipment to OE's and I have seen them do things like make a last minute cam change after the mapping was all finalized. Then they wonder why they get bad reviews. Even companies with years of experience seem to produce pretty awful mapping on new models at times.

Don't get me started on Hardly Davidsons.

 

[DallasJ]

Matt, love your ample use of big words defining special processes to skirt around the real subject of OEM final tunes are not optimum for "performance"

Yes, OEMs have magical sensors and test process I have no clue about. Underlying code within the ECU is quite amazing and something I cant begin to break down. Hell, most engineering done on OEM components are quite possibly "gasp" beyond my abilities.

But... I do know the basics of tuning and making power and economy around a race track through the modifications of said parameters. A 9.0:1 A/F ratio, which is what both my 95 Talon and 06 Evo run stock is not conducive for racing power or economy. The OP's SRT-4 is in the same boat. Sure, it'll keep the engine nice and cool for umpteen million miles but I couldn't give a rats-arse about that. I want to be fast and have a spare block on the back burner to toss in when my Fatigue limits are reached.

 

[JSteve2]

It may rub some people the wrong way, but Matt speaks the truth. Gone are the days where the guys down at the factory were making stuff up and the quality of your engine depended upon the part-to-part variability of the springs that were on the line that day.

If you improve the "performance" of the engine one iota from the factory now, it's only because you define performance differently than they do. Within the box of emissions, noise, fuel economy, and engine part life, the factory setting will be absolutely maximum performance. Small manufacturers, and certain low volume products are an exception to this.

It's inconceivable that a guy poking around in the dark is going to find an improvement, even if he is an expert (or even THE expert). He can't know all the interactions or parameters he would need to know (physical or electronic) what's going on in there, and he simply doesn't have the time to test all the variations. High volume engines will have several lifetimes of systematic testing performed before they go to production, by the people that are holding the code book and the hardware blueprints.

It's certainly possible to increase (X) from the factory setting, but it will always come at the cost of everything else that the engine was tuned to meet. If you want to increase HP, torque, fuel economy, whatever, you can. But you will be giving up emissions, noise, fuel economy, HP, engine life, or other parameters that you are not optimizing for.

Matt's point was (I think) that it's not a given that you will even increase the thing you are after any more, at least not significantly. You may make a change that will presumably increase HP, only to run into an interaction that counteracts what you are going for. Further, the opportunity available to increase HP is much lower than in the past when factory designs were not as finely tuned.

It's more difficult to improve now, and there is less improvement available. People who really know what they are doing can get performance beyond the factory tune, if they have specific limited goals and are willing to give some things up.

 

[LionelHutz]

Sure, manufacturers typically try to get the most power possible from their engines. With todays manufacturing the engine tolerances should be very close so they can set-up the electronics to make best use of the engine and the results should be very repeatable. So, there isn't much if any power left on the table in most naturally aspirated factory engines.

But, don't tell me that manufacturers would never limit the maximum boost pressure for long term durability or limit the rate of boost application to keep the driver out of trouble in a factory turbo or factory supercharged engine.

 

[DallasJ]

JSteve2 -- You might be right about factory N/A car's but when it comes to Forced Induction your just wrong, especially when it comes to ECU controlled boost on factory turbo'd cars (my world).

Evo 8,9, 10 -- +15-20% hp
STI -- +10-15% hp
SRT-4 -- +5-10% hp

These power gains are from flash alone and no other mods. The evo guys can go from a low 13 sec stock car to mid-low 12s with just a flash and running 92 or 93 octane. Its not rocket science or myth, just facts. Their is A LOT left on the table from manufacturers if youre willing to give up some NVH or life span.

Another thing to think about is the Japanese gentlemen's agreement that limited horsepower to 276 (lifted in 2004). Manufacturers of homolgated race cars overbuilt cars for smaller race teams but limited power by the boost pressure and tune. Not just a few cars here, Evo, STi, Supra, RX7, 300zx, 3000gt, Skyline, Silvia, etc. All limited to 276hp but capable of significant power increases just by playing with turbo pressures.

I really don't know what else to say other than you're ignorant to assume you cant make more power than the "Safe" tunes provided by the factory. Its been done for years and will continue to be done. Hell, even the Prius is getting modded to use both motors for acceleration and increasing electric motor current.

 

[1gibson]

But, nobody can object to flashing a more recent OEM calibration into an older vehicle, assuming no OEM hardware updates. Because of course there are improvements...

This tends to override the "OEM calibration is perfect so don't touch it" argument.

 

[JSteve2]

@Lionel: "for long term durability..." Agreed. It was right there in my post.
@DallasJ: "if youre willing to give up some NVH or life span" No kidding... If only I had thought to say something like that, maybe I could've avoided being ignorant.

When it comes to durability, the manufacturer is expected to pay for the engine up to X miles. If you want 15% more horsepower, which decreases durability to 0.65 X miles, they rightly expect you to pay for that. Or, you can do it yourself and void the warranty, which is also fine. On a non-N/A product, you are also throwing emissions out the window, which is an option unavailable to the manufacturer.

 

[SomptingGuy]

Add in the word "transient". It's rare to see transient performance figures reported. Staying within legislated values for all the baddies measured over fixed cycles or test procedures (emissions, noise, economy, durability, etc) doesn't need to mean that an engine can't respond brilliantly over the short periods when the foot is down.

- Steve