this car has been hell since the day i bought it, anywaymy problem is i just had to put a new block in because my fpr craped out and engine got too much gas and washed a cylinder out anyhow since i had the work done it has had an idle like it has huge cams in it. its not all the time its like 2 or 3 mins after you first start it so i took it to my mechanic and they tore it apart and said my cam key was busted so they fixed it and now it will only start if you hold on the gas and even then it sounds like its firing on two cylinders. then everyonce in awhile i can get in start it and it will run perfect untill i drive it then it goes back to firing on like 2 cylinders. so far i have put in a new cas, front o2, changed coilpacks and crank sensors new plugs wires and computer. the only sensors i havent changed is the rear o2 and the 2 sensors on the throttle body. im getting codes in this sequence 12 25 43 sometimes 21 then 55. if anyone has any ideas let me know i have had this car for a year and i redid alll the body work and paint and have only been able to drive it prolly a week total sorry so long just figured the more you know the more you can help

Sounds like you have an electrical problem. Your codes read as;

12- Direct power to ECM disconnected within 50 cycles
21- Upstream O2 sensor stays at center
25- IAC motor Circuit
43- Ignition Coil primary circuit

(btw, I got all this here http://www.2gnt.com/nuke/modules.php?name=Sections&op=viewarticle&artid=8 , for future reference :P )

Now since you've replaced the O2 sensor and coil pack, that would tell me #21 and #43 are harness/connector related. And since the coil harness (don't remember about the O2 harness) runs down around the EGR pipe that is infamous for making our collective lives miserable, and I believe the IAC wires run through there too, that's the first place I'd start looking. I'd look the harness over real good and if nothing was visable on the outside I'd slice the harness open and look at each individual wire to make sure there were no signs of melting.
And you said you replaced the ECM too, right? Well if that's the case then I'd tend to believe that whatever is causeing your other problems is causing the #12 code too. Long and the short of it, you got a wiring problem, good luck.

hey man thanks your a life saver looked over the harnes last night and the wires that go to the iac sensor and the other sensor on the throttle body were all melted togheter cut them respliced them and fired right up....now just gotta figure out why im getting code 11 now and its got a lope to the idle like its got a huge cam but it only does this wen its sat at idle for like 2 mins

Originally posted by limedoutclipse
its got a lope to the idle like its got a huge cam but it only does this wen its sat at idle for like 2 mins

Timing is off, imo.

Well the PCM code chart suggest checking the harness at the PCM and Crank Sensor, but like Driggs said, that's the "timing belt is off you dumbass" code, I got it once :shrug After changing the timing belt once you pretty much get the hang of it. Check the harness at the PCM first just in case it's something stupid, then order yourself an AFX underdrive pulley and get to work on that timing belt. As a little hint, get yourself some white out or something to mark the belt cam gears to help you line it up :thumbsup

thanks a bunch guys finnaly got the car all back together...im no mechaninc but if the timing belt was off wouldnt it idle like crap all the time myn only does it wen it sits at idle for a couple minutes with out touchin the gas...just wondering also the guy that did my motor he was trying to figure out why it was doing it last week and told me he tore it all apart and checked the timing and it was dead on top dead center and he is a friend of the family so i dont think he would lie to me but what do i know any input will help im gonna check the harness tongight. another thing is it gonna hurt driving my car with it like this?

I wouldn't drive it too far until it was all figured out, but that's me, what you do in that matter is your own personal choice.

Originally posted by Keith2172
I wouldn't drive it too far until it was all figured out, but that's me, what you do in that matter is your own personal choice.

Agreed. If the car is idling like shit due to timing belt alignment, you're just that much closer to catastrophic engine failure. You can park it, inspect the timing belt yourself (you can tell if three marks line up), or drive it and risk having to replace pistons and valves...

hey guys just finaly got ahold of the mechanic that did all the work and he forgot to tell me last time i took it there to figure out what was going on and he checked the timing that he belt was off 2 teeth so they fixed it put it back together and started it and it ran for a couple mins and then started doin it again and it had jumped one tooth... so they are now putting a new belt and stuff onto it.so hopefully that will take care of my code 11 problem

It doesn't "jump" 2 teeth, thats just due to installer error. I'm not bashing your mechanic, but if the cam is 2 teeth off, I'd be willing to bet that there's nothing wrong with the belt and he just needs to take a little more time with the install. As a side note, the first time I changed my timing belt I didn't judge it right either and put the car back together and immediately popped a CEL. I tore it down again and fixed it same day, spent approx. 8 hours on that SOB, but it's cause I didn't mark the cams and belt when I put it together.