So I swapped motors out of my 98 Xj into my 98 zj. Got it all put together no leaks and runs fine. The problem is when it gets warm outside or the engine is warm it starts hard. The only code it's putting to the obd2 scanner is the upstream oxygen sensor. Could that be the problem?

 

heat soak issue??

 

What do you mean by heat soak I'm pretty new to jeeps? I had the old Xj and it always ran great but the body was shot! The motor always ran great and started within 2 seconds.

 

heat soak is hard starting after the motor gets hot. Boils the gas in the fuel rail and it doesn't start real well Google heat soak and search this forum about it. Plenty of threads with solutions to that issue. If that's your issue.

 

Thanks ill check into it

 

I didn't know you could swap an XJ motor into a ZJ. Despite the fact that it's the same engine, the mounting is slightly different.