I am new here and hope someone has an idea why I am having issues with my car.


Here's the story in case any of it is relevant.
I put a racing cold air intake that sucked air from underneath my car. I didn't anticipate having a flash flood and my sister driving my car sucked water in my engine..ouch! No more engine so next I bought a used engine from a junkyard and had my car dismantler uncle do the job. This was obviously a cheap way out for me. Problem is he has no knowledge on diagnostic.


Now that I have my new engine in it sounds different and on cold starts it hesitates. It also came back with a check engine light for o2 sensor pre-cat/up-stream he apparently forgot to plug it back in.After plugging it back in and driving it awhile the light came back on. Got it scanned by autozone and it is the same issue. I have not fixed the O2 sensor yet due to being busy and I guess laziness at some existent.


My question is do you think it is the O2 sensor causing it to have trouble starting on cold starts or it could be something else he did wrong. Just looking for some idea's here.

Just to clarify it starts fine after the first start. But the first start takes a couple attempts before it takes over. To me it kind of sounds like a fuel issue. Correct me if I am wrong. Because it almost goes to start but then dies. It does this usually 3 or 4 times before it actually starts. Also sometimes when I am driving from 1st to 2nd I get a lag or stutter(occasionally).
possibly causes seem to point to emissions. Just don't know where to start..

 

The O2 sensor, make sure its not still water log or clogged up. Specifically if it's a 4 wire sensor bc the sensor breathes through the wire harness to compare the air to the exhause.

 

i ordred a new one