Guys I am posting this because I am lost with the car. For some background, I purchased a 2000 Accord with the 4-banger 2.3L. The car had a junk engine so I dropped it out and had a new one in its place within 5 hours. My problem however, is that the car is throwing several CEL codes. The first is P1259, the V-tec code and the second code is for the secondary O2 sensor. I am not sure what is going on, the V-tec soleniod has been replaced along with the O2 sensor. Another problem is that the car seems to be in a limp mode; it wont rev when the car is given full throttle, instead it stalls, and the idle is horrid. In fact, there is no idle it will bounce between 500rpm and 1200rpm. I am stumped, I want to make this car my DD but it is becoming difficult to diagnose what is going on. The engine has all fresh fluids, everything is plugged in from the swap, etc. Any suggestions, thoughts, etc?

 

I had this same problem after removing the throttle body and had a stuborn air bubble in the cooling system that I couldnt get out, and I finally got it out and the idle was perfect.
Purge the air out of your coolant while holding the idle about 2000 rpms after the engine is warmed to normal temp. Do this several times and then do it again. Hope this gelps, Good luck.

 

Purging the cooling system will help with the idle?

 

Yes, the ECU is confused and will make the engine idle bounce / surge because you have and air pocket in the cooling system. This sounds like it may be your problem or a big part of it anyway.