During the track day at Streets of Willow, I ran into one instance of getting enough knock to get the Ignition RON value to kick in and start increasing in value; I had topped off with a few gallons of Chevron before getting to the track, so maybe that threw off my knock resistance. You can see I was getting significant ignition timing correction on all four cylinders and it hit some threshold to cause the Ignition RON value to increase.
The best I can figure, when the summation of ignition timing correction for all the cylinders exceeds -16, the Ignition RON value starts to increase. There are spots where the summation hit -15 and -14, but those did not cause the Ignition RON to increase. After the timing correction is at a low enough value for a bit, the Ignition RON value starts to decrease.
Direct injection opens up new control strategies. In diesels of the last fifteen years or so, they use multiple injection pulses per power stroke which is why they run so much quieter compared to old diesel engines. The data log parameters in the Porsche ECU show three possible pulses. The Primary Pulse occurs at about 180 degrees which I assume is crank angle with 0 degrees being top-dead center before the intake stroke. So it looks like injection starts with the piston moving up on the compression stroke and the intake valves fully closed. The Primary pulse also looks to be the main fuel delivery pulse as the injection time trend matches the torque trends. The Secondary fuel pulse is interesting because it looks to be in reaction to knock as indicated by the ignition timing correction. The Secondary pulse occurs after 480 degrees of crank angle which corresponds to the piston moving down on the power stroke. There is a Third pulse, but I never saw any injection from it. I assume it’s to generate the crackle pop noises in Sport mode and I think that would happen by injection and igniting fuel during the exhaust stroke.
Looking closing at one of knock events, you can see there was a change in the Primary pulse start of injection (I’m assuming that’s what SOI stands for) and that was during the torque ramping up as indicated by the injection time increasing. When more timing was pulled a bit later, the Primary pulse SOI didn’t change however. I’m sure Porsche did a lot of work to figure out when and where to do the various injection strategies.
I often have the Accessport plugged in to track how the car is behaving and really to keep an eye on the fuel quality. Here you can see I actually got enough knock to cause the RON value to jump. As a reader noted, it’s possible for the race gas concentrate to not stay evenly mixed and this tank of gas has been in the car a few weeks. So it looks like I got down to the gas with lower octane in the tank. You can change what parameters you can display and six is the maximum number and I really appreciate the max/min values. You can data log many more parameters at the same time and the typical logging rate is about 30hz.
7 comments
If not going stiffer on the suspension, consider a DSC controller. Made a world of difference for brake dive. Also more comfortable on the street and can now use the sport suspension setting on my local mountain roads which were previously too bumpy. Still imperfect with high frequency bumps but better than stock. I tried to go the fairly minimal route and did camber plates and toe arms on my T.
Yup, DSC is already in the plans! The all-out plans would be Tractive coilovers with 80/100 spring rates. We shall see.
It’s incredible the amount of information that is required to properly modify a modern ECU; and also very impressive that Cobb has managed to design the Accessport to handle all of the communication / data with a user-friendly interface .
I’m really impressed with the power output information the ECU can provide. It seems like not too long ago it took a piggyback or standalone ECU to have access to that same level of information.
It’s hot in there! Maybe a GT4RS style intake is in order?
Thanks for your hard work, professional insights and for sharing all this.
I look forward to reading your updates as I too have a CT.
For a pure track car, I’d look to implement a GT4RS style window intake, but it’s a bit too radical and loud for street use for me. The T is really exceptional out of the box. The bigger brakes and extra cooling are strictly due to my car doing double duty as a track car. For street use, the stock intercooler system is *mostly* okay. I wish the cooling fans would kick on sooner to bring the temps down after the car has heat soaked after sitting after a drive. The IAT heat soak is really a sustained high power use issue at the track and not a problem on the street. Hmm, I’ll have to ask Alex if there’s a parameter on how to better control the fans for the air to water intercooler system. It’s my understanding the APR tune turns on the fans sooner or more frequently, but no information on the actual Porsche control strategy. If you are willing to tune your car, that’s the only mod I would say is a no-brainer for a street car. Everything else I’m doing to the car is tweaking to the nth degree but definitely not required.
Good morning!! I want to upgrade my 2017 FA20.
So far I have Cobb access port and full MAPerformance “bolt ons with a stage 2 off the shelf map. I want a pro-tune it’s just there is no reputable tuners within a 8 hour distance.
1. Map Cold air intake
2. Map Charge pipe
3. Map intercooler
4. Map high flow cat/J-pipe
5. ETS track edition cat back exhaust
6. Grimmspeed BPV
It runs good but I just know it has more to offer; I’m in the Philadelphia area? Thanks again
Lou
You can use Alex at Stratified like I do; I’m over a thousand miles away from him. You go drive, datalog, send the the logs to him, and he sends you back an updated calibration. I like getting data from real-world driving more than tuning on a dyno anyway. Nothing like the real thing where airflow and real world loading plays a role. The have plenty of tuning experience with the BRZ/FRS/GT86.