Rep Power: 118

I'm wondering why our ECU's can't be tuned. Correct me if I am wrong, but my understanding is that all OBD2 ECU's must be capable of accepting updated software, at least from a dealer scan tool. To me, that would mean that it is possible to reprogram it for improved performance. Is there some reason that no one can? Is the problem that no one has figured out how to trick the ECU into thinking that a dealer is updating the software so the ECU will allow it, or is there some other reason why no one can tune the stock ECU on these cars? Thanks

 
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You can tune them but there is no aftermarket option, premade.

You would have to find out what programming language the ecu is written in, and have the right connectors to read and write date. There may also be anti tampering software installed that you'd have to jail break.

There are some interesting diys on youtube that explain the process for other cars.

This used to be called "chipping" because people would write new maps for a certain ecu, then clone the changes onto chips to sell, that would replace the original chips on an ecu.

 
Rep Power: 118

That's interesting, thanks for explaining.

Another interesting that I found is that there are plenty of products available like this one to supposedly tune a Honda Stream 1.7 ECU (the ECU I have in my car) as well as the Edix, such as this one: https://www.gantuning.com/chiptuning...ad/1-7i-125hp/

There are also services in Asia and Europe to tune the Stream 1.7 as well as the Edix 1.7, with advertised power increases of 8-15+ HP. No idea if any of those products or services are legit, but it makes me wonder if there is some difference in the foreign ECU's that makes tuning easier or possible, like maybe a lack of anti tampering software. Or maybe all of those products and services are total scams, who knows.

 
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Those hp numbers sound reasonable.

I'd guess it's a simple air/fuel remap, probably a device that intercepts the O2 sensor and tells the ecu its rich, so that it leans out.

Lean is mean as they say... but what they don't tell you is that lean can also go pop-pop bang and detonate your engine. Lol

 
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I didn't think that the o2 sensor was used at full throttle? My understanding was since the ECU goes into open loop at full throttle the o2 sensor readings are ignored anyways, so skewing the readings wouldn't affect power at full throttle. Unless you are saying the device likely reprograms the ECU to run it leaner at full throttle?

 
Rep Power: 228

Depends on the model, honda have a larger closed loop setting than most cars.

Many manufacturers are in open loop from 80% throttle plus.

But depending on the vehicle from honda the MAP sensor is also consulted. So you can be in a gear higher than what would give you maximum torque, at 90% throttle, with a lower MAP signal because your rpm is low.

Example would be highway cruising at 3000rpm, in fifth gear at 80%.

 
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https://www.k20a.org/forum/archive/i...p/t-13276.html

Here's an example of what I meantiond above. If you're interested in similar information, Google "honda closed loop WOT"

 
Rep Power: 118

Makes sense, thank you for explaining! Is there any truth to the myth that power output can be increased by installing a resistor in the IAT wiring? Apparently the ECU advances the ignition timing less when the air is hotter to prevent knock, but if higher octane fuel is used you can trick the ECU into advancing ignition timing to make more power. Is there any truth to that?

 
Rep Power: 228

I'm not sure, but ignition timing advanced across the whole air/fuel/ignition map, isnt the best route to power.

If you look at a dyno tuned car the ignition map will show 0 advance in some locations, as well as positive and negative values.

I'd suspect that with a set value for you would see ignition problems somewhere within the map.

The main regions which differ from each other are

-idle
-low to mid acceleration
-low to mid deceleration
-vtec cross over
-mid to high acceleration
-mid yo high deceleration

-these groups are also effected engine load and MAP readings

There will be larger variations between these regions than within them.

 
Rep Power: 228

http://twinturbo.net/nissan/300zx/fo...your-ABCs.html


This link shows some different regions for high octain ignituon tuning. You can see retarded values, no change, and advanced values.

You can also see that within a region the values may only change by two or three units, but across regions change by larger amounts.