severe misfire during acceleration

[ky_kneedragger]

i have a 2000 gt and i installed a 2003 engine,i also used the engine harness that went with the 03 motor.i still have the 2000 computer in the car and i was wondering if this would or could cause misfire problems??? i have changed coils,plugs,camshaft position sensor and injectors and so far nothing has helped! it will clear up for a second the starts missing again...i'm gettin ready to set fire to it b/c i have worked on it for 4 days and spent 1300 bucks...needless to say i'm aggravated...help me out guys!!!

 

[squeak93]

Is it pulling any codes? Do you have everything plugged in correctly? (don't ask, but trust me its easy to miss stupid things).

 

[ky_kneedragger]

Is it pulling any codes? Do you have everything plugged in correctly? (don't ask, but trust me its easy to miss stupid things).

everything is hooked up,and the only code it shows is multiple cylinder misfire...

 

[Sanco213]

did u do a full long block swap? or short block? did you swap all sensors or none?

 

[ky_kneedragger]

did u do a full long block swap? or short block? did you swap all sensors or none?

i did a full long block and it still had the engine harness on it,but i just changed that and it still didnt help it..if you slowly get into the throttle it wont pop and crack as bad as when u just gun it....the original motor knocked like crazy but didnt cut out

 

[tri5333]

Just had the same problem with mine it turned out to be 3 bad plug wires

 

[Shiroelex]

Shot in the dark, but have you checked the computer? If a previous owner installed a performance chip and it has fallen out some, it can do some strange things.

 

[mrvax]

I'm guessing you have coil-on-plugs. If not, replace the spark plug wires.

Several things could be wrong. Consider taking the car for a custom tune. They can tell you a LOT about what's going on and have your new engine working at peak performance.

 

[Brute03]

are you having any other elec. problems? try checking all the grounds

 

[Notchbck93]

I've seen several goofy things with these cars:

1) Water down in the plug tunnels... causes short to ground

2) Trac control goofs up, causing multiple cyl misfire...turn Trac control off

3) Sometimes it truly is bad coils

4) If the coil boots are old, hard, and cracked, they can cause misfires as well.

5) Dirty MAF or filter (Over oiled K&N) http://www.stangnet.com/images/stories/docs/sn95_TSBs/98-23-10.pdf

6)Exhaust leaks upstream 02 can wreak havoc.


There are other mechanical issues that can cause misfires, but I doubt that is your problem.


If you like to read what some other members did:

http://forums.stangnet.com/675780-99-gt-still-missing.html