Hondata

hi
i have a question
i am used to entering manually (specs advertised from manufacturer of the injector) and fiddling a bit with injector dead time values , especially for bigger injectors (more than 550cc).

i ll be using rc750 in my car(edm fn2) , and i was about to modify the inj dead time table in flashpro , as i do with other management systems s300 , aem ems etc.
I checked to see if the dead times i got from rc match the ones in your ''big injector'' starting calibrations , but i saw that in your startup calibrations for rc 550-650 , the inj dead time map is untouched and exactly the same as the one for stock injectors.

That would cause poor closed loop operation and rough maps in general , should i suppose that these starting maps ''drive/manipulate'' the injectors behavior through other compensation maps(accel fuel etc)?

if not , i cant see how these maps would run smoothly...
Would u recommend to start with a stock map , and try to dial the correct dead times ?
wouldnt that work better than using the starting maps with stock dead times?

hoping for an answer

thanx

p.s
in afm calibrations , dead times are different than the race maps

thanx

The Civic Si starting calibrations were made before we had access to the injector latency tables.

First, we've found that the advertised injector opening times are often quite different from what we measure.

For RC750cc you'll need values of around 1.2ms @ 12V and 0.8ms @ 16V, so add between 0.1ms and 0.15ms to all the injector opening time values.

Our recommendation is to set the injector opening times when you first start tuning. If you are using a starting calibration or already have tuned the vehicle then it is not worth setting the dead time and then needing to re-tune.

Forgive me for raising this topic.

I had a question:

How can you measure the injector opening time values? Any reasonable method for amateurs? And how can you see in the datalogs the relationship of this values?

Thanks.

Itsuki wrote:Forgive me for raising this topic.

I had a question:

How can you measure the injector opening time values? Any reasonable method for amateurs? And how can you see in the datalogs the relationship of this values?

Thanks.

Any advice?

You can set the opening times fairly accurately quite easily. First you need to realize that 99.9% of the time the injector voltage will be 14.1 - 14.4 volts. The only other time the voltage will drop is while cranking, and at that point the injector dead time is only a small fraction of the injector pulse, and it does not really matter if the opening time is 0.1 or 0.2 ms out.

This is best done with a stock engine.
- With the engine warm, at an idle adjust the fuel tables to give a short term fuel of close to 0%. The voltage should be about 14.2V
- Increase the electrical load by switching on the headlights, rear demister and apply the brake very lightly (otherwise the vacuum will change the engine idle). The voltage should drop to about 12.5V
- If the short term fuel trim goes positive (adding fuel), then the dead time is too low. Increase the dead time across all voltages by about 0.05ms (50 us), and re-test.
- Likewise if the short term fuel trim goes negative, then the dead time is too high.
- When finished, road test in 3rd gear at about 3000 rpm. Very slowly reduce the throttle until the injectors shut off. If the short term fuel trim goes negative (the most common case), then your dead times are still too high.
- R18 engines run at both 14.5V and 12.5V (to save fuel) and require tuning at both voltages.

Thanks for the explanation. I will check in my car.