Let's discuss Transient Fuel

[homebuilt]

I am really interested in learning more about how to adjust the transient tables.

If anyone could share some additional experience or insight I would be grateful.

Ideally someone could explain how the VCM is mathematically using the table values to adjust the commanded pulse with.

I tried to get some information from support on how the table data is being used and they felt this was a tuning question and didn't provide an answer. I would think this would have to be known to create HP Tuners.

[Wnts2Go10O]

I am really interested in learning more about how to adjust the transient tables.

If anyone could share some additional experience or insight I would be grateful.

Ideally someone could explain how the VCM is mathematically using the table values to adjust the commanded pulse with.

I tried to get some information from support on how the table data is being used and they felt this was a tuning question and didn't provide an answer. I would think this would have to be known to create HP Tuners.

its all about airmass.
http://redhardsupra.blogspot.com/200...ss-models.html

[homebuilt]

Just a little light reading uh? I love this stuff so I appreciate the link.

Anyway, so far I haven't run across an area on his website where he shows the transients coming into the equation.

I also found a post by Greg where he provided enough information for me to figure out that my min fuel mg should be adjusted down by the same factor that the injector static flow was increased. So in my case that gives me 0.013 instead of the 0.006 I was using based on the 31.xxx conversion from the min pulse width I had entered (not the same as the min PW the injectors are capable of).

The 0.013 min fuel mg change really helped! My surging has really improved and light throttle acceleration isn't as jumpy as before.

I have to redo the portion of the VE table that a tuner I used did. He was holding steady conditions but he was tuning based on the the STFT (LTFT disabled). This didn't seem to result in good data I think it was because the transients were adding a lot of fuel and the trim was taking it back out.

Once this is fixed, I still need to find or learn the step-by-step process for calibrating the transients.

[homebuilt]

Bump

[homebuilt]

If you've read this post and have some experience with the actual transient calibration procedure, please share.

Some specific questions I have are regarding adjusting the boiling time table. I didn't know if this table can simply be adjusted globally or should it be row by row like the impact factor?

[homebuilt]

It is this - rich dip on the map reduce, increase lean spike map. I reduce evaporation, or increase the impact of factors that table?

I'm sorry, I don't understand your question or if it was directed to me??

Anyway, I wasn't successful in my exhaustive attempt to locate comprehensive information on tuning the transients (the Mega-squirt write-up was somewhat helpful) so I have proceeded to figure it out via my own trial and error.

For the tip-in lean conditions I'm gradually increasing the applicable high MAP portion of the impact factor. For the let-off rich dip I'm gradually decreasing the fuel boiling time in the applicable low MAP portions.

I am really early in the learning curve regarding getting the transients dialed in. Based on comments from an OEM calibration engineer, I understand that transients are the hardest part to get right.

I was asking general "How To" questions in this existing thread however I will include my tune and a scan just in case it can help shine any light on the subject. The attached scan is long and only has a few points where I was testing the transients. You just have to scroll though it an watch the TPS reading.

[DRTWRK]

Would someone please share some light on this topic

I have been experimenting with Transient Fueling for some time now and found varying and inconsistent results. I can alter either or both Evaporation Factor and Transient Fuel Mass Gain/Impact Factor and initially find expected results and can verify by logging IDC and obtain satisfactory fueling on immediate throttle transition into boost. What I can not understand is why the expected results will only work through 1 or 2 key/start cycles. For whatever reason the IDC reverts back to percentage of change comparable to stock setting.

Is there some kind of adaptive or learning feature in the computer that we don't have access to? The values in the cells reflect just as I input.

I can Log on first start up after changing settings and see my IDC increase 10 to 70% or higher depending on what value I input and will repeat those values every time I hit the throttle during the first startup cycle. I can hit throttle 10 times and I will see IDC shoot up 10 times and be very consistent.

I then turn ignition off and restart engine. Start scanner and while logging find IDC reverts back to values just like I never made any changes.

Can anyone explain?

[lwrs10]

Well I have been playing around with transient fuel quite a lot as of late. I think I might have mine nailed down, and had to drastically change my evap table. As in double it for some reason......maybe because I am using a very custom setup. I am by now means an expert at this, but I am putting together a little how-to on Transient Fuel adjustment.

[HartRod]

Well I have been playing around with transient fuel quite a lot as of late. I think I might have mine nailed down, and had to drastically change my evap table. As in double it for some reason......maybe because I am using a very custom setup. I am by now means an expert at this, but I am putting together a little how-to on Transient Fuel adjustment.

Any update on this?

[JamesLinder]

http://www.hptuners.com/forum/showth...to-guide/page2

http://www.hptuners.com/forum/showth...to-guide/page3