AFR Problem

[AndyF]

If your wideband O2 sensor went bad, then it probably corrupted the Learn Table in the process. That happens if you don't have the Learn Table locked down.

Holley advertises the Sniper as "self-tuning" and it is to some extent, but it is also "self destructive" at the same time. They don't advertise that part. You have to be aware of how the Sniper can Learn the wrong things and make mistakes. Keeping a watch on the Learn Table is very important since once the Sniper Learns the wrong thing it can really mess up a tune.

[Danny Cabral]

If your wideband O2 sensor went bad, then it probably corrupted the Learn Table in the process.

Yes, I'd Clear the Learn Table if it's been corrupted with erroneous values from a failed WBO2 sensor. Always save your last "known to be good" Config File.
See "Clear Table", center of page 9: http://documents.holley.com/techlibrary_199r11259.pdf (Holley Sniper EFI Help Manual - EFI Software, Tuning & Datalogging).
The 3.5" TSLCD doesn't have the option to "Clear" the Learn Table (if it's corrupted with erroneous values), so you'll have to use the Sniper EFI software.

[Chris805]

Yes, I understand failed WBO2 populate Learn Table. My question is do the Learned values effect the Base Fuel Table even if you never transfer it?

[Danny Cabral]

Yes! The Learn Table is a modifier of the Base Fuel Table. These two tables actually function together as one, because the Learn Table values are directly applied to the Base Fuel Table. The Learn Table just indicates how much the Base Fuel Table has been altered (modified). The Base Fuel Table values don't change, unless you Transfer Learning To Base (which then allows you to blend the Fuel Graph so it's smooth). It's the Learn Table itself, that contains constantly changing values. When the Learn Table values stop making significant changes, the ECU is finished self-tuning. The purpose of the Learn Table is not to achieve similar values, high/low values (0% or 100%), or any value in particular. It's simply indicating the amount of tuning applied to the Base Fuel Table. Read this thread (LINK), that's what it's all about.

[Chris805]

Thanks for everything everyone. I'm 99% sure I fixed the issue turned out to be a bad plug wire somehow the terminal that snaps onto the spark plug got deformed and wasn't staying snapped onto the plug. I changed the wire and everything seems to be OK now.

[AndyF]

A bad plug wire can cause multiple issues with a Sniper depending on if it's on the same side as the WBO2 sensor or not. Best way to protect yourself from things like that is to keep track of your baseline tune. You should know where your engine idles in terms of MAP, AFR, IAC, etc. Once you know those values then you can quickly look at the dash when something seems wrong and you can tell if it's at baseline or not. One cylinder not firing will cause the IAC to open up, raise the MAP and it might change the AFR if the bad cylinder is on the same side as the wideband O2 sensor.

The downside of a self-tuning system is that it doesn't know when to tune and when to raise an alarm. OEM engineers design in check engine lights that come on when the engine is out of bounds. The Sniper doesn't do that, it just keeps trying to make adjustments and it'll chase the tune all the way down the rabbit hole.

[Danny Cabral]

FYI: If a faulty WBO2 sensor causes the engine to run poorly, the tune (GCF - Global Configuration File) should not be programmed to allow this to happen. When the engine is tuned & running well, you should've decrease the Closed Loop and Learned Compensation Limits % to lock in a good tune. I decreased my Learned Compensation Limits to 2% in the idle area (10% elsewhere). My Closed Loop Compensation Limits are 50% or less at WOT (20% elsewhere). When the Learn Table values stop making significant changes, the ECU is finished self-tuning. You can then Transfer Learning To Base, which then allows you to blend the Fuel Graph so it's smooth.
http://forums.holley.com/showthread....2523#post62523 (Holley EFI Tuning Tips & Information - Read 4th & 5th paragraphs.)
http://forums.holley.com/showthread....7370#post47370 (Holley EFI Closed Loop & Learn Table - Especially posts #2, #6 & #11.)
http://forums.holley.com/showthread....ension-Harness (WBO2 Sensor Information - Read 4th paragraph under "Wideband O2 Sensor Notes".)
http://forums.holley.com/showthread....ension-Harness (Read 5th & 6th paragraphs under "Wideband O2 Sensor Notes".)

This indicates that your current state of tune is way off. You should be able to temporarily disable Closed Loop (to ignore the WBO2 sensor), and run the engine in Open Loop mode (Closed Loop Parameters - System ICF) until the replacement WBO2 sensor arrives. If not, the Base Fuel Table is poorly tuned, because its been relying on significant Learn Table modifications and the WBO2 sensor to compensate for the AFR.

If the original WBO2 sensor was damaged. You can't just replace the WBO2 sensor, and restart the engine. You must reload a "known to be good" Global Folder, reload the base calibration, or at the very least, clear the Learn Table of the corrupted values (from the defective WBO2 sensor).
http://forums.holley.com/showthread....ents-Read-This! (Initial Checks & Adjustments - Read This!)

There's a WBO2 sensor testing procedure at the end of "Wideband O2 Sensor Notes":
http://forums.holley.com/showthread....ension-Harness (WBO2 Sensor Information)

The Learn Table (Fuel ICF) should be populating the table with numbers. Like this: Holley EFI Learn/Self-Tuning Demonstration. If not, determine why it's not Learning. Check your Closed Loop/Learn Parameters. "Enable Closed Loop" and "Base Fuel Learn Enabled" are the only two parameters that need to be check marked.
http://forums.holley.com/showthread....5760#post45760 (Scroll down to "Learn Issues, Self-Tuning".)

I'd Clear the Learn Table if it's been corrupted with erroneous values from a failed WBO2 sensor. Always save your last "known to be good" GCF (Global Configuration File).
See "Clear Table", center of page 9: http://documents.holley.com/techlibrary_199r11259.pdf (Holley Sniper EFI Help Manual - EFI Software, Tuning & Datalogging).
The 3.5" TSLCD doesn't have the option to "Clear" the Learn Table (if it's corrupted with erroneous values), so you'll have to use the Sniper EFI software. If the original WBO2 sensor was damaged. You can't just replace the WBO2 sensor, and restart the engine. You must reload a "known to be good" GCF (Global Configuration File), reload the base calibration, or at the very least, Clear the Learn Table of the corrupted values (from the defective WBO2 sensor).
http://forums.holley.com/showthread....ents-Read-This! (Initial Checks & Adjustments - Read This!)

You have to be "Online" with the ECU to view the current state of the Learn Table. Unless you have the current GCF (Global Configuration File) saved on your laptop, then you can see it without being connected to the ECU.

• Laptop "Online" Communication With ECU: Next to the “Toolbox” button, is a button to indicate the following status of ECU/laptop communications. Offline: Is shown when the ECU is not powered or the USB cable is not connected. USB Link: Is shown when the ECU is powered and USB connectivity is established. However, the user has not chosen to select the “Online” mode, and the Laptop & ECU are not communicating with each other. Changes made at this time on the laptop, are not being updated in the ECU. Online: Is shown when the Laptop and ECU are communicating. At this point, changes made with the laptop are real-time updated in the ECU. • "Get From ECU" & "Send To ECU" - ECU Sync window: When you connect a laptop and go "Online" with the ECU, you first want to click "Get From ECU". This updates your laptop with the latest ECU "state of tune". If you click "Send To ECU", you overwrite all the Learning the ECU has performed since the last time that laptop was connected (because you're not sending the latest, up to date values to the ECU). The only time you should click "Send To ECU", is if you're just sending a Global File change to the ECU and you haven't driven the vehicle since the last time the laptop was connected.

Originally Posted by Danny Cabral Sniper EFI Replacement Sensors - Auto Parts Store CTS Sensor: Standard Motor Products TX3 TPS Sensor: Standard Motor Products TH191 IAC Motor: Standard Motor Products AC416 WBO2 Sensor: Bosch 17025, 0258017025 (LINK/LINK/LINK/LINK) (The Sniper EFI 2 bar MAP sensor is internal with the ECU. The Sniper EFI IAT sensor is a circuit board sensor that measures one throttle bore.) Innovate Motorsports HBX-1 Heat-Sink Bung Extender is great for protecting the WBO2.