Just swapped a B18A1 into a friends 89 civic. Had a ZC in there before. The CEL is hard coding. Im not sure which one but my question is when the CEL is on is the ECU in "limp mode"? We think its the coolant temp sensor that has the wires crossed but not sure yet. Also the idle fluctuates alot. Goes from about 800 to 1500 and just keeps see sawing.

What would cause the idle fluctuation?
Would it go into "limp mode"?
Does "limp mode" affect performance?

Also if anyone has a diagram for the vacuum lines i would appreciate it. Some arent hooked up. Thanks guys.