I mentioned in the last post I’d go into more details about HPTuners. This time I want to talk about the Ecotec ECM tuning changes done so far. I’m far from being an expert however one needs to start somewhere…
Vehicle Anti Theft System (VATS)
The first and most important task is disabling VATS. This is a prerequisite when doing an engine swap such as what we did here. Failing to disable VATS renders the engine inoperable. On earlier ECM’s GM devised a system by which the ignition key had a special resistor that would match a receiver in the ignition key tumbler. This “match” would enable the ECM to fire the engine. With those early ECM’s it was possible to wire an inline module and basically fake out the key resistor. With modern ECM’s such as the one controlling the Ecotec, the VATS became more advanced. With the aid of HPTuners though, this is a simple change in the flash file burned into the ECM.
Mass Airflow Recalibration
In bowtie6, we replaced the stock plastic intake with a smaller, more direct intake manifold. The reason was not for performance but because the stock intake was too big and got in the way of the steering shaft. The air filter housing was also replaced with a cone-shaped K&N air filter. There is simply no room under the hood of the TR6 for the large box that holds the stock air filter. These changes forced relocation of the Mass Airflow (MAF) sensor. As expected, the stock settings for the MAF did not match the new configuration. This manifested itself in a rather rough idle and poor performance.
Tuning the MAF took some doing. I won’t go into all the details but suffice to say it took a few hours worth of driving down the road and logging data with the VCM Scanner. Using the VCM Editor I was able to dial in the low and high MAF tables to more desirable values. This resulted in smoother idle and better performance.
Seeking Professional Advice
This is where the tuning process gets a bit pricey. After going through several books and reading many long hours’ worth of posts I decided to find a local expert. Sure enough I found a person with a great knowledge and familiarity with HPTuners and tuning GM engines. However this came at a price. The results though, made a huge difference.
As expected, fuel efficiency is the ahead of pure performance in the stock ECM. This shows up the way the commanded air fuel ratios are pre-set across the RPM range, spark tables and the way that power enrichment activates proportional to throttle angle – among other things. After quite a few alterations the ECM is delivering more performance at the expense of fuel efficiency. The results are astounding: throttle response is much more livelier resulting in more power being delivered and overall the engine is much smoother across the entire rev range. It is now very easy to make the Ecotec reach its 7000 RPM redline.
The next step will be to take bowtie6 to a dyno. Been there, done that before but this time we will be tweaking the ECM This will allow even more accurate dialing in for extracting that last bit of power. Also, something that is yet to be modified are the VVT tables. The 2.4 Ecotec has variable valve timing and this first tuning did not touch VVT. Who knows what we can do with this?
Another avenue left for exploration is E85 Ethanol. I’ve been intrigued for a long time about this source of fuel. FlexFuel vehicles have a special metering device that allows the ECM to calibrate itself on the fly. I don’t have that metering device but I have HPTuners and this will allow a special E85 calibration flashed into the ECM. Where I live E85 is very easy to find – there is a very large fuel station just down the street from my house – so this will be a fun experiment. Granted, flashing the ECM to run E85 without a metering device means E85 has to be burned exclusively. However, changing back to straight fuel is easy to do, simply by reflashing the ECM.
I realize to each his own and this is not for everybody. However, having all this technology at your fingertips (literally) is remarkable. Why would anyone want to waste time on those relics of fuel metering called carburetors is beyond me.
Stay tuned… Soon bowtie6 will be the first E85 Ethanol powered TR6… 🙂