Recently we helped a local 1.8T owner tune his Golf Sportwagen. Although similar to the 1.8T development car we have done extensive work with, this one had a slightly different hardware choice. We hadn't tuned a 1.8T using a Golf R High pressure fuel pump and injectors, so this was a fun challenge. The main customer concern was that the vehicle experienced cold start limp mode and would need to warm up before clearing the faults and restarting the car. A tedious morning routine to be sure. So while our primary goal was to sort out this customers fuelling/running issues, we also took advantage of the time we had with this car to log the existing tune and see how it differed from our 1.8T development and of course, see if we could improve it.For fuelling in our own development vehicle, we kept the 1.8T direct injectors and added 980cc multiport injectors with a Hellcat Low pressure fuel pump upgrade. We utilized an OEM MPI fuel rail and simply upgraded the low pressure fuel sensor. As we all know, when it comes to tunes there's more than one way to skin a cat, so having this customers car would be a nice comparison between two different fuelling methods. MPI (in ours) vs. Golf R injectors and Golf R HPFP. The detailed list of hardware modifications are listed. Hardware:CTS Turbo DownpipeCTS Turbo IntercoolerCTS Turbo IntakeOEM IS38 Turbo upgrade (Golf R turbo)OEM Golf R HPFP OEM Golf R fuel injectorsBaseline Dyno run on existing tune Before getting into it, we ran the car on our hub dyno to get our own baseline and log what the car is doing on it's current tune. This will help us see where we can safely make adjustments. The peak numbers were impressive, but our philosophy at TuneZilla is to make as flat of a torque curve as possible, and carry out the power throughout the entire rpm range (as much as possible). So seeing this big spike in torque meant we would have a different driving experience for our customer. Our only concern was if our customer would be open to our tuning style after seeing how his existing tune graphed on our dyno. It's a different feeling on the butt dyno when you have a flat torque curve vs. the spiky torque curve. Where one will feel fast because of the harsh peak and quick ramp up in torque, the more gradual onset of power from the flatter curve will feel smoother (haters will say "slower") but generally ends up being faster. After checking the dyno for a baseline, we head over to our log viewer to examine the data logs and see what the car is doing behind the scenes. Click here to view the complete Data log - BaselineWe see in the log that the short term fuel correction (adaptation) on the current tune is pulling around 12%, and even goes as much as 20% closer to redline to target their specified lambda. In a perfect world, we would want short term fuel correction to be zero, but in reality having it within 0-5% is considered acceptable because of ever changing driving conditions. After making changes to the fuelling, timing, and rebuilding the injector maps and boost curves, we ended up with something closer to what we consider an optimized tune. green areas =TuneZilla gainsred areas = TuneZilla loss What we were able to come up with was a much flatter torque curve, which produced more torque and horsepower past 4200 RPM. What we gave up was the snappy peak of power from 3200-4200 RPM. After 4200 RPM, we see a peak delta of 27 lbft of torque, and a peak delta of 30 wheel horsepower around 6000 RPM. Comparing peak figures, we gave up 12 lbft of peak torque in favour of an additional 19.92 of peak WHP. Overall, adding more usable torque across the power band, and increasing horsepower all the way to redline. Comparing peak torque loss and peak horsepower gain.The drawback to a flat torque curve is that almost always, you will lose the hard peak and "snappy feel" of the car rapidly accelerating to the peak. The benefit of a flat torque curve is that your vehicle will carry out the power farther and it won't rapidly fall out of power midway through the rev range. With this the car may not feel as fast from a dig, but there won't be a sudden fall off and your car will continue to accelerate hard throughout the power band. It's also a lot more forgiving on the engine internals. Now it's a matter of driving style. Do you want your car to just feel fast, or do you want it to actually go fast? But we can't just show you what we've done on the dyno and not show you how that affected the logs and the long term drivability of this vehicle. So we take another look at our final data log with our tune to see how the new fuelling looks. Click here to view the data log - TuneZilla tuneWith our adjustments, we're now running a way lower short term correction (adaptation) in the fuel mixture which hovers around 0-3% . A considerable improvement over the previous correction which you can see in the actual and specified lambda readings as well. Now the car no longer runs extremely rich, and aside from a heavy right foot should get better fuel mileage, which is what you originally bought the 1.8T for in the first place, right?! You can view more of our 1.8T tunes in our Tune Catalog. Or, if you're considering an alternative upgrade path for your vehicle, you can check with our Calibrators to see what we can do for you and your build by creating a Ticket - There's no cost for our Tuning consults.
