Two Problems:On/Off Throttle bucking and Ignition related

Barq · Post by **Barq** » Thu Sep 03, 2009 3:47 pm

I have two problems.

1. I'm experiecing a lot of bucking when I get on and off the throttle. It feels like as soon as I let off or get on the gas, the car bucks a bit. It's almost as if the engine can't decide if should be on the gas or off the gas.

What is the cause of the bucking?

My datalog shows that when I get off the gas, the Tpedal and Tplate hit zero, but the AFR gets rich at the same time for a bit before it leans out. Then when I get back on the gas, the AFR is lean for a bit before it corrects itself back to the 13s area. The graphs look like the AFR is lagging behind.

2. I had to reduce a lot of the timing from the ignition tables to get rid of knock. My tables are no longer smooth. When viewing from 3D, it no longer looks like a smooth hill. There are a few dips at the bottom in the lower RPM range near rows 6,7,8,9.

Should I reduce some of the ignition timing near the dips to smooth out the tables?

3. I might as well throw in a third question while I'm at it. When using the Lambda overlay to see what adjustments should be made, should I be making every single adjustment listed or should I just be removing fuel from the intersection point of RPMs and Rows at a certain cam angle, just like tuning the ignition?

Thanks in advance.

Post by **Spunkster** » Thu Sep 03, 2009 4:08 pm

The overlay is just a recomendation and may not always be acurate. Use it as a guide in tuning. The tables should be smooth.

Without the calibration and a datalog showing the problem it is newarly impossible to tell what might be going on.

Barq · Post by **Barq** » Thu Sep 03, 2009 4:15 pm

Would it be possible to email you the calibration and datalog to you?

Post by **Spunkster** » Thu Sep 03, 2009 4:56 pm

please post them here in the forum

Barq · Post by **Barq** » Thu Sep 03, 2009 5:10 pm

Hopefully this works...

My ignition tables look a bit wacky from all the ignition timing I took out to get rid of knock, could you help me out on that part too?

Hulk69 · Post by **Hulk69** » Wed Sep 16, 2009 5:35 am

As a new user to new user post/observation:

1. I notice this too. It typically, like 90% of the time, happens when I let off the gas right as, or within 400rpm after, VTEC engages at 4750. There's two ways to minimize this and I will address those in the third question response.

2. I've not messed with ignition yet. Haven't had to. Adjusting the low/high fuel tables a bit has removed all knock from my setup. If your fuel isn't correct, I wouldn't mess with ignition yet. But the pros here at Hondata might correct me on that one as I'm not absolutely sure rules of thumb from the American V8 cars I've worked with in the past will apply here as well.

3. What I ended up doing was following the help contents file that comes with FlashProManager on how to adjust fuel. Those instructions along with the Youtube Video on A/F adjusting, links are on this website or you can search Youtube for "Hondata", helped me to make very accurate and productive changes to my fuel tables. Now that I've got my fuel in the ballpark for idle, low RPM conditions and high throttle RPM conditions, all my knock has gone away completely. Also, now that my fuel is set better, letting off the gas right after VTEC engages hardly ever causes bucking. You can also be aware of where your RPM's are and instead of letting off the gas, either change gears or just hold in the clutch while braking.

Hope that helps. Just my observations thus far. 8)

Post by **Hondata** » Wed Sep 16, 2009 8:05 am

Your ignition tables are not smooth at all - I suggest you start from a base calibration again.