So rebuilt long block 15 miles blah blah blah its running lean.

Attachment 155660
Attachment 155661

Pic of the #1 plug (all look like that). And the o2 sensor compared to the stock one. Can't reuse it cause the wires broke.

Could the o2 sensor not getting a good reading cause it to run lean? I've tried adjusting the TPS and it fixed the rough idle I had but not the lean condition. I don't want to put any more miles on this until I fix the lean condition.

It runs fine and has plenty of power, the plugs are just white. It will sometimes pop or misfire on decel a little but I think I have that fixed.

I'm not sure you can tell a whole lot in 15 miles. Engine is fresh rebuilt, so its tight, and will run a bit warmer. This could add to your possible super clean burn. The only info I would rely on is an exhaust sniffer to tell me what the actual readings are. You could monitor O2 voltage/readings but that won't necessarily tell you precisely what the engine is doing, although it should get you in the ballpark if its trying to over-richen the mixture. Just my thoughts....

And from my experience, a decel pop is usually indicative of an over rich mixture. Causing excess fuel to enter exhaust, where it ignites. Or an exhaust leak sucking in oxygen which then ignites excess fuel.

What kind of o2 do you have?

Brand is borg warner I think.

Exhaust pop doesn't happen very often if at all. Like I said it runs fine plugs are just white and I don't want to ruin my brand new engine school starts in less than 2 weeks.

It could be an exhaust leak but it didn't do it with the old engine. Also it only does it after a high rpm throttle chop. So it may very well be over fueling. Old engine was not right though it wouldn't rev past 3k due to cam issues.

Just took it for a 50 mile drive. Timing and tps set as good as I could get them. Went over a bump and it started missing but it turns out one of my sparkplug wires just jumped off.

Has plenty of power and doesn't backfire anymore so I think its good.

400 something miles on it and the plugs are still the same for the most part, I think it just burns really clean still. Still having problems on decel and very light throttle especially when cold, so I think I'm gonna grab an o2 sensor and TPS off a junkyard truck when I get the chance and see if that helps.

Engine has good oil pressure though and doesn't leak anything. There might be a small leak at the back of the valve cover but its not worrying me for now. It doesn't use any noticeable amount of oil and oil is still clean. I changed it at 200 like the instructions said and adjusted the valves and retorqued the head bolts. One of them moved a tiny bit but the rest were still good. I think I'm gonna do it again at 3k just to be sure.

Power is good it'll cruise 80 with relative ease. Engine is all stock except for 210cc injectors and just a glasspack in the exhaust.