i have a 79 280zx dropped a valve so i got a new motor/tranny out of an 81 280zx 2+2 ran great in the car i pulled it put it in my car and now i have one insane sputter/backfire its hellish no power cant get over 2500 rpm spits sputters but idles nice ive put new plugs wires cap rotor fuel filter i got spark and fuel, changed MAF and injectors WHAT IS WRONG!!!!! i put the damn thing up for sale its drivin me so crazy ha

 

Is the firing order correct and the timing right?

 

yea i checked like a million times im so lost.......

 

hmm.... when you swapped the motors over did you take all the sensors an put them onto the 81 motor? Or did you also swap to the 81 harness and ECU?

 

you have to swap the wiring harness and ecu unless they are exactly the same. In your case they are not the same. 280zx doesnt have a MAF. it measures air volume not air mass. The reason you are having problems is because you dont have enough information to do it the right way. Now you jacked up a car you liked with your ignorance. You did the right thing by putting it for sale. what kind of car you going to butcher next?

 

Wow that was harsh. Kinda funny, but still...
Yeah, either swap harness and ecu from other car or swap afm,tps,dist, ect. from original motor till it runs right. If you already swaped the motor and got it running your almost there. Follow through and get it running right.
My 2 cents

 

between 79 and 81 there are some differences, but nothing that really should stop it from running. does the 81 have the cas system or did you swap the dizzy out to the 79 model. that and check the tps adjustment. you could swap the thermo housing with all the sensors in it just make sure they are all the same. its and easy job. other than that if you kept the same afm and its settings didnt change, then i dunno with no other details.

 

Completely wrong.

Engines are pretty much identical with a few minor exceptions. That being said you do not need to swap over the harness and ecu. In the 81 you will have the CHTS near the #5 spark plug. (not needed if you use the stock 79 harness). Zero is correct about it not having a MAF, it has a AFM which means AIR FLOW METER (not air volume).

Since getting this newer engine did you do a compression check and make sure the fuel is getting to it at the right pressure? Perhaps the injectors you swapped out are blocked as well. You did not butcher it, don't listen to Zero he will never make it to Hero

Oh and shady unless he swapped in a turbo setup there would be no CAS.

 

thanks skittle, i just wanted to cover it just incase it was there. you never know what has been done to these cars by the previous owner

 

No N/A 280ZX has a CAS and no 280ZX has a MAF unless otherwise modded.

 

what parts did you take from the old engine nd swap with yours important when you changed injectors did you put in new seals so you don't create 6 vacuum leaks ? when car is idleing spray wd-40 or engine start fluid by injectors were they insert into intake ,,if engine revs different get new inj seals,also pull one inj wire off inj at a time and see if engine revs diff it should as you go down through #1 to #6 if no change temporally swap closest inj wire with other inj to see if inj prob or wire prob if inj prob place tip of screwdriver on inj color area and tap screwdriver with other toolseveral times to wake up inj.good luck

 

Correct. In fact IIRC only the '81 280ZX turbo has a CAS - the '82 and '83 turbos have an optical encoder in the dizzy (which is part of what you change when you run the Z31 ECU/chopper wheel). I think the NA dizzys are pretty much all the same with possibly the exception of the electronics module on the side but you'd have to check on that (not sure if the difference on the modules is between the Z/ZX or different years of ZX).