car runs bad

I have a 98 eclipse nt.. And I have just rebuilt a 420a and put it in

Whenever I first start the car it spits and sputters and doesnt want to go anywhere.. which is the same problem i had with the last motor.. but after the car runs for about a min it idles good and runs fine.. but if i shut it off and start it right back up i have the same problem for a couple mins then its fine again..

i checked the codes and my o2 sensor is reading really hot and it also says that its out of time.. so i went back and checked the timing and its perfect..

any information will help i just wanted someones oppion before i replace things that dont need to be replaced.. thanks

I have a 98 eclipse nt.. And I have just rebuilt a 420a and put it in

Whenever I first start the car it spits and sputters and doesnt want to go anywhere.. which is the same problem i had with the last motor.. but after the car runs for about a min it idles good and runs fine.. but if i shut it off and start it right back up i have the same problem for a couple mins then its fine again..

i checked the codes and my o2 sensor is reading really hot and it also says that its out of time.. so i went back and checked the timing and its perfect..

any information will help i just wanted someones oppion before i replace things that dont need to be replaced.. thanks

So you had a motor that was doing something. You rebuilt it, and it's still doing the same exact thing? Sounds like you didn't need to do all that.

Did you replace the front O2 sensor yet? Sounds like the ECU isn't getting good info from somewhere and maybe messing with timing. How's your coilpack?

ok the previous motor had bad rings in the 4th cylinder.. and the shop told me the reason it was running like this was because of the rings.. so instead of fixing that and being out of a car i got a diff motor and rebuilt it.. i swapped them and still have the same problem... im gonna replace the o2 sensor today and see what happens.. i just dont understand how it could run fine after it runs for a couple mins

im assuming that my coil pack is fine because i have two of them and i swapped them and it still does the same thing

When the car warms up, the oxygen sensor tells the ECU to run in a different loop (open/closed). It's the actual O2 sensor that heats up from the exhaust gas. Once that hits a certain temp, then the signal gets sent to the ECU to change loops.

I'm rushing at this explanation but you should be able to get the point.

oh ok. im gonna replace it tmr and see what happens.. i appreciate all the help

i also had one more question.. when ever i swapped the tranny over i drained the fluid out and put new fluid in.. except i filled the tranny through the speed sensor.. it doesnt work and is throwing a code.. it worked properly before i took it out.. i was wondering if i could have damaged it when i put it back in?..or if i am just over looking something.. thanks