I got a 91 hatch with a DOHC ZC swap and it started sputtering when first accelerating (bottom of 1st and bottom of 2nd sometimes) and during hard acceleration (idk what rpm because I still have the std cluster). Ive replaced the spark plugs, distributor rotor, cap is still new, and the fuel filter and it's still sputtering. If the car has been sitting for a few hours it will run fine for the first 5-10 minutes then it starts to sputter again. Idk what it could be at this point, I'm thinking fuel pump, tps, or a vacuum leak somewhere? Any thoughts would be greatly appreciated.

 

Does it get better after it warms up? Does it happen at idle too? Any codes being thrown?

 

Doesnt get better as it warms up and it idles kinda rough and at a lower rpm than usual. Gonna check the codes tomorrow cause I've had a check engine light since the swap was put in

 

If I remember correctly the ZC is rated to be warm idle at 720 - 750. Did you do the MPFI conversion yourself? What ECU are you using?

 

No it was done by a shop and I'm running a chipped ls ecu but I don't see that being the Problem because it's been running fine for months

 

Are you throwing any codes?

 

It seems to be throwing code 17 which is VSS which would make sense because my speed sensor is bad. but that wouldnt be the cause of the sputter. How soon after driving do you have to read the code? Car was off for about 10 minutes before i went and checked

 

The code will be thrown as soon as the car is started. What is you're definition of "sputter"? Is the car missin'? does it jerk back and forth real bad? does it feel like it is loosing power when it "sputters"? Does it back fire?

 

The CEL doesnt come on until ive been driving for a while. Sputter = sounds kinda like its missing not really loud popping like its backfiring, car doesn't jerk back and four it just hesitates when taking off and sounds like putt putt putt (if you get what i mean) then it will do it randomly under hard acceleration (but obviously at a faster rate cause its at higher rpm)

 

I kindda worded that code thing wrong, if it has a stored code in it THEN it'll come on as soon as you start the car. Well you replaced the spark plugs, wires, rotor and cap.....Have you check your ignition timing?

 

Im going to later today. Is it possible that it just jumped timing? And if the timing was off would it still run fine for the first ~10 minutes after it sits for a while like it does?

 

If the timing was off it would be affected all the time and you would be getting code 9....but then you have a chipped LS ecu so I have no idea how that works. You can always just double check it and the ignition timing. Sounds more like a ignition timing to me.

 

Problem fixed plug wires had slices in them and were arcing. Thanks for the help though g I appreciate it

 

Awesome! Glad to hear you got it fixed!