whats up i just replaced my LS motor with another doner LS motor due to detonation, now that i have the motor in the car starts but has a very very rough idle, and is popping and missing ALOT!!!!!!!!!!!!!!!!!!!!!THROUGH THE intakemanifold plus theres alot of back fire when let off the throttle i also blew a 50amp fuse in the fuse box under the hood but was replaced with new .So maybe i have a short im not even sure,i've been messing with this car for the past month or 2 and have no idea what the hell is wrong with it! i get spark and i get fuel and fireing order is straight.. please if you have any info it would be great..thanks

 

timing off, firing order, rotor, cap, leaded gas, clogged cat, you have CEL?

 

rotor and cap are brandnew i just filled the tank half way with regular..and firing order is good.. im guessing..well im hoping its the timing. and the cat is gutted..

 

ttt

 

just to make sure what is the fireing order suppose to be. im pretty sure i have it right.. it's been the same since i'v put the motor in..! never touched thme.. i mean i took the cap and rotor off..but i placed the wires back in the same exact postion..if anyone has pictures or anything info about firing order please let me know..

 

Firing order is 1,3,4,2, and have you checked to see if the cams are in timing? From your description, it sounds like the timing might be off a tooth or 2.

 

If you do not know where the number one spark plug wire goes, put the motor to tdc, remove the distributor cap, the rotor will be pointing to the number one cylinder. Since you have it at tdc take a look at the crank and cam gears to see if the timing is right.

 

thanks for the info.. i actually got the car started. now that i was able to move it..i would press the pedal all the way down and i would go as slow as a snail..could that be bad timing.. or totally different..

 

how is the idle?

 

eratic... up/down sometimes 500 somtimes. 1200 then back to 1000

 

it acutally wants to shut it self down..but it doesnt..but it gets that low that it feels like the car is going to shut down... then sometimes after i get off the throttle it would back fire..

 

I'd check the cam timing and the ignition timing. If both are good, check compression, it could have bent valves. Check valve clearances first though, they may be too tight and not closing fully.

 

ttt

 

i'm having the same problems with my car....i just put a 98 ex motor into a 96 cx hatch. same problem , back fire, no power down low, no check engine codes.