Built a nice 588 and finally got it done and running. Gotta tell you that this thing is scary if you can't use it in constant closed loop (which in a boat is nearly impossible). Makes for real ease of use and looks cool at SIMA but it does not work in marine environment.

I'm not a Holley basher and have not fully chosen another system yet but I spent some time on this and just wanted to give a word of caution on it. I have roughly 3K spent on it and making a nice custom harness etc. Plus another 1500 in dyno time. It's coming off -

It will work. Give Haxby or another expert a call. Are you running the V4 software?

You can try to post your specific problems here and see if others can help. There seems to be a few sharp EFI guys on here.

Yes and didn't say it wouldn't "work". I said it doesn't repeat. Very dangerous to use IF not always in closed loop. We did 7 pulls back to back after getting a final tune perfected. Once taken out of closed loop, the system was all over the place and as much as 2.5 points higher than what was programed to do in closed.

I've seen all I need to. It's nice if in closed loop; if NOT, then it's absolutely nutz to trust your engine to this thing.

Also, the firmware versions are tied to certain boards. I have an L board so according to Holley it's not compatible with mine. The J boards were a little more consistent but you can't get them any longer.

I've never heard of that issue before. I am on my second set of Holley efi setups and have not had the issues you describe. I would give someone a chance to help out and see if it's something obvious. If what you describe was the normal then we would have a bunch of blown engines with the system. There are a ton of car guys that use the system in open loop or after it gets tuned they turn the tuning gain down to %5 correction and that's not enough to compensate for 2.5 points on a blown 588.

Are you sure it's not as simple as a modifier pulling your fueling out of line?

-Intake air temp modifier
-Coolant temp modifier
-etc

Mark at MER Performance has had great luck with these systems. He's worked directly with Holley on the 572s in Yankey's Bullet, which are in this dyno video. http://merperformance.com/projects.html

I by no means have the experience as Alex..... I just finished up another two 525 EFI conversions using the Holley HP with bigger cams and modified heads along with a modified 525 intake and TB...Without seeing his set up with settings it could be very true his modifiers are throwing things off.... also is the water temp constant at 140 or 160 ? Without the Global Folder or Data log.... hard to say..... Of all the kits I've done never seen a inconsistency... I can take it out of learn and watch AFRs remain as targeted ...

I replied; in your post... You need to be specific on your issues, they are very unclear.... Doesn't repeat, what exactly do you mean ? Send your Global Folder and Data log...Who is giving you support on tuning and parameters ?

It's as simple as making a run and doing the exact same run 15 mins later with zero changes. even if modifers were cause they should do same thing twice and they don't.. i have the graph; it's not difficult to read. When you spend all day on a dyno and you make the same pull 5 times in a row and get different a/f curves but with no changes it's a flag. I wonder how many people have ever got the tune where they wanted it and then went back and did more pulls after taken out of closed to see the variance. According the guys at GT Performance, they see this all time. I saw it with my own eyes. It jumped from roughly 12.4 to 13.95 on a whim. See if i can post the pic later. I don't have the attachment option any longer and I'm not big on pics saved online.

I can't use any % correction once installed permanently.