Not the most exiting event in my build, but I figured I would post this for completeness’s sake. From my first start, I had one symptom that bugged me. The engine ran well at speed, but at idle it would “cycle” between lean and rich. Watching the Sniper handheld, the A/F ratio would cycle between yellow and red, which caused the engine to rev, go lean, and then recover. It wasn’t terrible, but it definitely bothered me while sitting at stop lights. I was hoping the self-learning Sniper EFI computer would eventually cure this, but it didn’t.
A couple weeks ago, while I was driving into town with my wife, the A/F suddenly pegged high and the engine starting flooding with fuel. I was able to limp home with the engine belching black smoke, and my lovely wife was not impressed. I immediately suspected the oxygen sensor. When I forced the Sniper in Open Loop mode, it ran better, which apparently is one of the signs of a bad O2 sensor (i.e., because the sensor is ignored in Open Loop mode). Anyway, just as I was beginning the troubleshooting process, the O2 sensor completely quit, showing an “Unplugd” value on the handheld:
That made it pretty clear what the problem was. I ordered a new sensor from Holley for $119.
https://www.holley.com/products/fuel.../parts/554-155. I understand you can get the same (or equivalent) sensor a bit cheaper elsewhere, but I figured I would stick with Holley just in case this didn’t actually fix the problem (i.e., to rule out that problem was from a non-compliant sensor). Long story short, the new sensor arrived from Holley, it was a 15-minute repair (it can be done through the hood opening), and everything is working fine now. The A/F ratio is stable and perfectly in spec, no more cycling at idle, and the system is back in learn mode with no problems. She sounds better than ever!
Again, not a big deal. I just wanted to post this in case someone else has the same symptom with their Sniper EFI.
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Originally Posted by JB in NOVA
Not the most exiting event in my build, but I figured I would post this for completeness’s sake. From my first start, I had one symptom that bugged me. The engine ran well at speed, but at idle it would “cycle” between lean and rich. Watching the Sniper handheld, the A/F ratio would cycle between yellow and red, which caused the engine to rev, go lean, and then recover. It wasn’t terrible, but it definitely bothered me while sitting at stop lights. I was hoping the self-learning Sniper EFI computer would eventually cure this, but it didn’t.
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