Idle issue after CTS hits 150°F.

[RockinRobin]

Thanks! I thought Sniper 4500 had 8 injectors, or are you referring just to the ones on the primaries? Yeah, I'm a little scared to try to wind that spring while it's on the manifold. Maybe just some lubricant, adjust the link and call it good.

[GPatrick]

Yes, eight in your case.

[RockinRobin]

Interesting: The secondaries close OK when the engine is off, but if you rev it up slowly, it hangs. If you blip the throttle it closes. FWIW, I think I'm just going to keep blipping the throttle if it's a manageable workaround. I may have an opportunity to take it to the track this Sunday if the weather cooperates. I want to make sure the changes I made did not adversely affect anything else. Thanks to all for the help! Would you like to see another Config File and datalog?

[GPatrick]

Take a datalog at the track so we can see how it does under WOT conditions. Take another datalog just at idle, and yes, include your latest Config File.

[RockinRobin]

I'll take a datalog of idle today. Thanks again!

[RockinRobin]

Here's datalog of idle from cold start air temp around 60°F. I see the IAC Position stayed high until the 1st time. I blipped the throttle about 2/3rds into the datalog, then it came down.

[AndyF]

With a race engine you tune the idle just like you would with a carburetor. Put the system in Open Loop at idle and then adjust the Base Fuel Table either leaner or richer until the engine idles how you want it. The AFR doesn't matter since it won't be accurate with a big race cam. Ignore the actual AFR and ignore the Target AFR at idle. Set Closed Loop to come on at 2500 RPM. You'll be responsible for creating the Base Fuel Table from 1500 to 2500 and then the computer can take over after 2500 RPM.

You need a laptop and the correct cable to do this. With the engine running you open up the Base Fuel Table and you use the up or down arrows to enrich or lean out the mixture. You just go richer until the idle speed slows down and then you go leaner. Just like a carburetor. You'll quickly figure out what the engine wants just by the sound. You can also watch the IAC. The happier the engine is, then the more the IAC will close an the higher the manifold vacuum (inHg) will be.

[a b c]

You have a classic case of the WBO2 sensor sensing an atmosphere that has not been ingested by the engine and/or an incomplete combustion process. The give away is when CL Comp comes into play and tries to reach the Target AFR selected, no matter how much fuel the ECU throws at the combustion process it can't reach your requested low target. Personally, when possible, I raise the Target AFR at idle to something reasonable for the ECU to reach. In your case, you could start with a Target AFR of 15.2:1 and see what the CL Comp does with it.
The other option (without changing the engine combo and exhaust) is do as already suggested and don't use the ECU to control AFR below a given set point your engine chooses.

On a side note, if you haven't had someone calculate the required fuel for this engine and put those numbers in the Base Fuel Table, don't just go out and stand on the throttle and see what happens. It's not a carb. and will not meter fuel like one, it will only do what you tell it to do. If you're using leaded fuel, trust the WBO2 sensor even less. I mention these points for two reasons; 1) You have more than 1500 HP of fuel available and are only asking for 700 HP of it near 8000 RPM. 2) What fuel are you using for over 13:1 compression? Anything with leaded fuel will corrupt the WBO2 sensor fairly quickly, leaving it unreliable in short order.

[RockinRobin]

Thanks for the advice! I use 110 octane race fuel which is of course is leaded. I keep a couple of new WBO2 sensors in the trailer, the question is how to know when it's time to replace them.

[Danny Cabral]

Yes, manually tune the idle/off idle area of the Base Fuel Table if you're not allowing it to Closed Loop or Learn at idle. However, don't completely disable Closed Loop/Learn:
http://forums.holley.com/showthread....ension-Harness (Read 2nd paragraph under "Wideband O2 Sensor Notes".)

[RockinRobin]

Danny thanks for the WBO2 sensor info! I just ordered one and will have my Bosch ones as a backup.

[Danny Cabral]

Just to be clear, the Sniper EFI only uses the Bosch LSU4.9 17025 WBO2 sensor (LINK).

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) (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. https://www.holley.com/brands/holley...ce_components/ (Sniper EFI Service Components)

[AndyF]

I took a look at your datalog and you're using about 20 lb/hr of fuel at 1600 RPM idle. That's probably double what the engine needs when idling with no load. Pull your plugs and look at them, they might be fouled. You need to manually tune the Base Fuel Table when you have Closed Loop turned off.

How much timing do you have at idle? With that cam you probably need at least 20° of timing, maybe more. You might even want to run locked out timing on that engine.

[RockinRobin]

So the Sniper cannot use the NTK WBO2 that's for methanol and race fuels?

[Danny Cabral]

No, and the only "WBO2 Sensor" selection in EFI Parameters (System ICF - Sniper EFI software) is Bosch LSU4.9 WBO2.