Reaction times

[Darrel Goheen]

I'm struggling with one of my Stock cars with reaction times. They are kinda all over the place (more than normal). I'm new using a two step. In one of my cars my RT is typically very consistent but the other one isn't. Both using Holley HP EFI and using it for the 2 step. According to data logs the two step varies about 200 rpm. It seems that has to affect RT's? Thinking about going back to footbraking to see if I can get the RT more consistent. Looking for feedback. Thanks.

[Hacksaw]

A 200 rpm variation of the 2 step will only slightly alter your rt's, unless you are so low on the leave rpm that you could be wandering below the camshafts working range. IMO

[Sean Marconette]

Darrel,

You need to tighten up the rev limiter set points. Do you not have it set for the soft limiter? You should see 2 set points the high and low RPM. I run the same system, and my settings have a 50 RPM difference. For example 7200 for the high and 7150 for the low. You should see in a data log that the engine is maintained between the high and low. This was one of the fixes with v4. There were a lot of complaints on the rev limiters doing what you just described and that was addressed with v4.

Sean

[btrc]

Sean,
I have been thinking of upgrading to V4 from V3 but haven't because V3 has been working OK for me but maybe this is a reason to upgrade. Any other notable changes they made for V4? Did your V3 global folders upgrade OK?

[Sean Marconette]

Originally Posted by btrc

Sean,
I have been thinking of upgrading to V4 from V3 but haven't because V3 has been working OK for me but maybe this is a reason to upgrade. Any other notable changes they made for V4? Did your V3 global folders upgrade OK?

Bob,
I bought my system in Jan 2016 when v4 had just been released. So I had no previous experience. I did just update again to the current v4 release last week before racing. I was worried that it could have issues with a known tune being screwed up with that update. There was a lot of people complaining about the 2 step and high rev limiter having too much drift as Darrel described with v3. V4 solved that and had some other upgrades. But you have to select the right rev limiter to narrow the rpm window as I described earlier. The current revision has colored or heat tables which doesn't really matter to me. I can look at the cell and decifer if it's adding or removing fuel or timing. Now it changes the cell color if you want to use that feature.

If you go to the Holley EFI software you can download the revisions and what was changed between v3 and v4 and now the updates for v4. There are some things to make sure you go back and fix is what I had read about upgrading to v4. If you have another computer that you could use and install v4. Then copy your v3 files and test run it on that machine, then you could compare the old vs new information before pulling the trigger and upgrading your ECU. If you decide to stay with v3 you have not screwed yourself. If you upgrade use the machine with the new software and compare any diffences between the two afterwards. If all is well upgrade your other machine and don't look back. Clear as mud??

The Holley EFI forum is a great place for help and information. Racers and installers that respond very quickly to any question.

I deal with building automation systems, and the last thing I want to do is paint myself into a corner and not have a way back out!

Sean

[Darrel Goheen]

Originally Posted by Sean Marconette

Darrel,

You need to tighten up the rev limiter set points. Do you not have it set for the soft limiter? You should see 2 set points the high and low RPM. I run the same system, and my settings have a 50 RPM difference. For example 7200 for the high and 7150 for the low. You should see in a data log that the engine is maintained between the high and low. This was one of the fixes with v4. There were a lot of complaints on the rev limiters doing what you just described and that was addressed with v4.

Sean

Thanks Sean, Dan Cabral that runs the Holley forums says to use spark, high only. I understand this was introduced in V4. I've always used V4. I'll definitely try the soft setting. I'd sure like to keep using the rev limiter for launching but I feel 200 rpm makes a significant different in RT. On my chevelle it sure does anyway but I only footbrake it. Thanks again.

[Sean Marconette]

Try it with the settings I described. My main rev limiter (high) is set for spark high only, but my 2 step is set as described earlier, so it's a tighter setting. I had my 2 step set as you do and did not like what was seen on my separate data acquisition data logs. I would pay more attention to what Scott (S2H) says. He races and installs this stuff.

Sean