Hi folks,

I upgraded to a Haltech Elite from my old Power FC a couple years ago and ever since, I've had a very specific issue that I've not been able to figure out.

If I'm in boost, and let up on the throttle at a medium rate, the car bucks pretty violently for a moment as if it just cut fuel or spark for a sec. If I let up on the throttle all the way and very fast, it doesn't happen. If I let up on the throttle very slow, it doesn't happen. This is super annoying on track for example, as it makes it really difficult to modulate power while in boost with any smoothness.

I ended up taking it to a local tuner specifically to see if they knew what was going on. He said he definitely felt the issue I was describing, and said that he thought the problem was that the car was going into decel and cutting fuel for a sec. I don't think that's right, as I took a log and it didn't show that decel was active when the problem happened. I suppose the surefire way to tell would be to turn decel off entirely and go for a drive, I'll do that soon, but again I doubt that's the problem.

Here is a quick screenshot of when it happens, I did this twice. While in boost, back off the throttle but not all the way off. There's a bit of a lean spike right when this happens and in the RPM line, you can even see the ripple from the car jerking around.



I've attempted to try and fix it by adding fuel to the cells in the mid to high RPM range at low to 0 MAP. That helped somewhat, but it's still there. I mean, that lean spike looks like a throttle transient symptom I suppose, but it only happens when I let up on the the throttle, if I depress the throttle at the same rate, everything is fine. Plus, as I understand (but correct me if wrong) transient throttle fuel correction for negative throttle input only dis-enriches the mixture, and I need to richen it up.
Of course maybe the lean spike isn't even the cause, but a symptom of something else, I don't know!

I'm tuning the car myself but I'm no expert by any means, so any advice even for a beginner would be excellent.

 

Post your cal file and the actuate day file.

 

Cal file attached, rename the .txt extension to .e2000-242 (had to change it to something the forum would upload). I'm assuming 'actuate day file' was a typo for 'actual log file'? I've attached that as well, if needed I can grab another log with whatever you want to see. Let me know if those come through OK, and thanks for taking a look.