Idles fine, almost dies into drive, then recovers.

[xyzrbs]

So I've got a new install and I'm trying to get it dialed in. It's still learning, but I've been driving it for a few days.
The issue I'm having at present, is that it idles fine, but it stumbles and almost dies when shifting into drive, and then recovers quickly and continues to idle fine.

TPS = 0%
IAC = 2-5% at hot idle
Idle RPM = 770

Is there a tuning adjustment I can make to help with this? Thanks!

[Danny Cabral]

The issue I'm having at present, is that it idles fine, but it stumbles and almost dies when shifting into drive, and then recovers quickly and continues to idle fine.

Check the things mentioned in the thread linked below.
http://forums.holley.com/showthread....ents-Read-This! (Initial Checks & Adjustments - Read This!)

The problem is probably Fuel Table related. Look at where this happens on the Base Fuel Table. Determine if it's stumbling due to a rich or lean condition. IF you selected the proper base calibration, I'd look at the Fuel Graph to ensure the Base Fuel Table is smooth (laptop software). It's probably not; so enter the Fuel Graph and blend everything in, so it looks smooth. One aspect of viewing the Fuel Graph: It's better to zoom in, by highlighting segments of the Base Fuel Table, and click "Graph". This method offers much greater detail. Looking at the entire "Fuel Graph" will almost always look smooth, because it's not as magnified. Also, the Timing Table must be flat at idle, meaning the same value used in the entire idle area (especially if using Idle Spark Control).

If you'd like to manually tune the Base Fuel Table while the engine is running, read below:
Left click & drag to select a group of cells, then use the CTRL & Arrow keys (▲►▼◄) to change the highlighted cell values.
The ▲ & ▼ arrow keys adjust the Base Fuel Table slowly (one tenth at a time). The ◄ & ► arrow keys adjust it rapidly.
Or you can left click & drag a group of highlighted cells, and right click "Offset Selected" to adjust the entire cell group.

[xyzrbs]

Did a little homework as prescribed. Initial Checks & Adjustments seem fine. Zoomed in on Fuel Graph for the 700-800 rpm area, and it's super smooth. Base Timing is flat in the 500/700/900 RPM area as well (25º for the three RPM ranges). I also grabbed a datalog of the event, and I've attached a snapshot of a zoomed view. I'm just not sure how to interpret it. Let me know if you have any other thoughts. Thanks!

[Danny Cabral]

I also grabbed a datalog of the event, and I've attached a snapshot of a zoomed view. I'm just not sure how to interpret it.

I'm seeing the Fuel Table is too lean in the area where you shift into drive. Or the MAP kPa spike causes an excessively rich condition (False Lean AFR) from the higher region of the Fuel Table. Either way, shifting into drive shouldn't cause such a spike in MAP kPa, especially with your mild camshaft (Link). This area requires tuning.

Zoomed in on Fuel Graph for the 700-800 rpm area, and it's super smooth.

A smooth Fuel Table (Graph) is good, but it still has to be the right amount of fuel.
http://forums.holley.com/showthread....7286#post57286 (Additional Information)

[xyzrbs]

Made some progress. I read as many of your thread recommendations as I could. I even tried creating & loading new calibrations with no changes to this problem. However, what I ended up with was adjusting the AE vs. MAP RoC value. I found that mine was set at 7 - an old value from previous software I guess. So I gradually started adjusting down, starting at 5. I noticed an improvement! However, I had to go all the way down to 1 to get the best results. I've attached a new datalog graph of the results. Is 1 too low? Are there any other indicators that would manifest themselves if it's too low? I've driven it a good bit and it seems to be running great overall.

Also Danny, I want to thank you for all of your input and support. You really bring a lot of value, and I know I have personally benefited quite a bit. Thank you, sir!

[Danny Cabral]

However, what I ended up with was adjusting the AE vs. MAP RoC value. I found that mine was set at 7 - an old value from previous software I guess.

Decreasing the AE vs MAP Rate of Change, lessened the effect of the MAP kPa spike from shifting into drive. Also, if the Base Fuel Table is too rich, less Acceleration Enrichment is required.

So I gradually started adjusting down, starting at 5. I noticed an improvement! However, I had to go all the way down to 1 to get the best results. Is 1 too low?

No, tune according to what the engine likes. If at some point, your tuning resolves the excessive MAP kPa spike (when shifting into gear), you may have to increase the AE vs MAP Rate of Change again.

Also Danny, I want to thank you for all of your input and support. You really bring a lot of value, and I know I have personally benefited quite a bit. Thank you, sir!

You're welcome, and thanks for the compliment.

[ianmapes]

I was having the same issue and used this method to resolve the lean spike (false lean? Did you ever figure out your Base Fuel Table and inch it back up from 1? At the moment I’m just pleased to be able to back out of my driveway without waiting for the engine CTS to reach 160°F.