Sudden erratic behavior, high AFR.

[Twelvepointfour]

Hi there. I have a 351 Cleveland in an Aussie XE Ford Falcon wagon running a sniper and a hyperspark. I installed the Holley parts a couple of years ago and while I haven't put on more than a couple of thousand kilometers, I haven't had any trouble to date! However, at the end of last week my brother was borrowing the car and while it started off running perfectly, about an hour into his drive it suddenly had a rough idle, black smoke, and bogging down with increased throttle and on take-off. He also noticed an increased difficulty in starting. My brother isn't used to looking at the handheld, so he didn't notice, but when he brought it home it seemed to be hitting an AFR of about 34 constantly. At idle the IAC was sitting at 100% for the most part (I'm pretty sure that's not normal, but not 100% confident).

We of course hit the forums pretty quickly seeking an answer, and couldn't really find an exact match. We took the plugs out and they were all fouled, so we replaced them and the car ran mostly fine on a quick test run. Oh, I also re-ran the tuning Wizard so most of this was on a base tune which worked perfectly when I installed the system!

The next day, with no changes and the new plugs still in, we had a difficult time starting the engine, and it was back to a rough idle and high AFR!

I have ordered a new CTS, after finding a similar problem on here with that being the solution. I was able to do that because it was cheap, but can't afford to throw new sensors at it without being at least somewhat confident in a solution. So I've got the datalog and the Config File to attach, and hopefully someone can make something of it. I have looked, but I can't make heads nor tales of it. I'm very interested in learning, but don't know where to start! Datalog 300722.zip. Hopefully someone can be of help, it would be greatly appreciated. If I can provide more info let me know! Thank you in advance, Chris

[Danny Cabral]

I'd start by replacing the WBO2 sensor.

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)

Learn Table corrupted, exhaust leak upstream of the WBO2 sensor, defective WBO2 sensor, fuel pressure (LINK), IAC Position about 5% at hot idle, vacuum leaks, ignition misfires/RPM signal problems, wiring issues (LINK), battery/charging system functioning, fixed orifice PCV valve (LINK), ignition timing synchronization (LINK), Base Timing Table and/or Target Air/Fuel Ratio table programmed wrong, analyze all sensors on the Data Monitor/Gauges, etc.
http://forums.holley.com/showthread....5760#post45760 (Scroll down to "Typical Idle/Running Issues".)
https://www.youtube.com/watch?v=rmnxKLjM25g (Wideband O2 Sensor Test/Diagnosis - it works!)
If testing the WBO2 sensor key-on/engine-off, the sensor heater will time out, so you'll need to work fast.
If you need more time, the WBO2 sensor test can be performed with the engine running in Open Loop mode.

[a b c]

I agree, looks like an WBO2 sensor issue. You could take a moment and look in the throttle body to verify all four injectors are applying fuel while it's idling or even at key on during the prime shot. You will need a helper to turn the key on for the prime shot inspection.

You could also run this test to verify an WBO2 sensor circuit issue: https://www.google.com/search?client...ake+clean+test

[66FAIRLANE]

Hey Chris. I'm in Adelaide too, small world. Did you have a good tune saved? You could put it back and turn off Closed Loop, or blow away the Learn Table in the current one and put it in Open Loop and see how it runs.

[Twelvepointfour]

@Danny Cabral: Thanks Danny, I will order one. I don't want to spend money, but by the sounds of how frequently they fail, it sounds like it can't hurt having a spare on hand. That said, I'll try the test you & a b c suggested! Am I right in that a reading of 34 is running lean, but blowing black smoke is more an indication of running very rich?

@a b c: Thank you as well. I did have a look when my brother was here, and it's definitely shooting fuel in. I might confirm that all four are working!

@66FAIRLANE: It sure is a small world. Only new to Adelaide, but absolutely love it. Unfortunately, I stupidly ran the Wizard without saving the tune. I assume it's lost? If so, I've lost over 2000 KM of self-tuning. But I really should get it professionally tuned anyway so I guess it's not the end of the world. What do you mean by "blow away the Learn Table?"

UPDATE: I went out to try the brake cleaner method of testing the WBO2 sensor, but it stays on "initializing" and doesn't actually give me a reading. Does this indicate anything, or am I doing it wrong?

[Danny Cabral]

@Danny Cabral: Am I right in that a reading of 34 is running lean, but blowing black smoke is more an indication of running very rich?

Yes, 34.0 AFR is very lean, and black smoke is very rich. A classic symptom of a defective WBO2 sensor in Closed Loop.

@66FAIRLANE: Unfortunately, I stupidly ran the Wizard without saving the tune. I assume it's lost? What do you mean by "blow away the Learn Table?"

Yes, the Wizard overwrites your previous GCF tune. He means Clear the Learn Table with the Sniper EFI laptop/PC software.

UPDATE: I went out to try the brake cleaner method of testing the WBO2 sensor, but it stays on "initializing" and doesn't actually give me a reading. Does this indicate anything, or am I doing it wrong?

Maybe the battery is low, but the first quote above indicates a defective WBO2 sensor. Just replace it.

[Twelvepointfour]

Thanks Danny, I'll order one. We will know for sure in a week or so when it arrives, postage in Australia is crap.

[Danny Cabral]

See post #2 above. Try a Bosch 17025 WBO2 sensor.

[Twelvepointfour]

Good news! WBO2 sensor arrived today. I just chucked it in and kicked it in the guts, muuuuuch better. Unfortunately, I lost 3000 KM worth of self-tuning. But that just means I need to drive it a bit. Thank you all very much for your help, it's very much appreciated!

I guess one final question. Is there a reason for the WBO2 sensor to fail? Or is it just luck of the draw?

[Danny Cabral]

http://forums.holley.com/showthread....ension-Harness (Read 5th & 6th paragraphs under "Wideband O2 Sensor Notes".)