Discuss all things tuning in this section. News, products, problems and results.
I have watched the videos and think I have a good grasp of how the injectors function but just have a few questions.
I am going 12inj setup and before I install all the hardware I am individually tuning 2 sets of injs (asnu 1050cc and the cobb 1300cc inj), MAF has been dialled in.
1) The stock inj on the R35 are 570cc and the base maps for ecutek show 570cc in their Inj Flow table. When I tune the 1050cc Asnu injs their data shows to put in 975cc in this table not 1050cc. Is this because the 1050cc is rated using different fuel and you need to set this flow value based on the density of the fuel used ?
2) I am now trying to tune the 1300cc cobb injs and using the data provided by Cobb shows to use 1290 for the flow (for 93oct) or 875 (for e85) , if I am using 98oct unleaded do I start with the 1290 value as its still unleaded petrol ?
Process for tuning (Assuming the deadtime value is accurate and voltage stable)
Do you first run the car at idle and check afr / trims and stability of rpm and only adjust the min open time value to you get a nice idle / afr / trims ?
Then when that is stable , adjust the flow scaler to make sure the afr / trims are good throughout the entire engine load range ?
Is that the general process ? I am just trying to work out how to get both of these values perfect.
The general technique is to start by getting the injector scaling in the ball park under light load and around 2000-3000 rpm. What you're trying to do here is get the fuel trims as close as you can to zero. The actual injector scaling number is usually different to the actual injector flow just to confuse matters so while you can use the injector flow to get you started, it's not uncommon to be 10-20% lower than the actual flow data would suggest.
Once you have the scaling dialled in you'll also need to adjust the latency data. The latency has more effect at small pulse widths and less at larger pulse widths. If you find that your fuel trims are perfect at 3000 rpm and light load but you're seeing positive trims at idle then you need to increase the latency. If you're seeing negative trims then you can reduce the latency. It's an iterative process as you may need to also tweak the scaling once you've made a change to the latency. You also need to allow time for the trims to stabilise to really see what's happening as often the trims will be a little positive or negative for a few minutes after a hot restart.
The entire process is covered in detail in our practical reflash course if you don't have that already.
Hey Andre , thanks for the quick reply. I dont have that course but will look into getting it. Thanks for the info, the trims are pretty close so looks like back and forward with those values till I get it right. Its more at higher loads that fuel is being removed so I'll play with the injector scaling a little. Thanks again.
After viewing the reflash course (big shout out to Taz for his help here) I have managed to tune the 1300cc injectors to have trims around 100% during cruise and idle(s) (in park, in drive and AC on).
However, when I do a 3rd gear pull to see how the trims behave during higher engine loads I see the ecu taking fuel and goes to around 92%. Because its specifically only at higher loads can this only be MAF related or are there other tables that could effect the trims in this range ?
Ecutek have a high speed enrichment table that I have disabled to eliminate that table and the MAF was tuned on stock injectors and looked good so just at a loss to know how to get the trims closer to 100% at higher loads now that the injectors are good during cruise and idle.