s13 idle problems and dropped cylinder

[tgeny79]

I bought a 1990 s13 that was an auto that was converted to a manual. The last owner says he rebuilt the motor and milled the head. The car idles like crap, very lumpy and I think the timing chain is off a tooth. I have yet to fix that but I was going to go drifting er..driving the other day and I went to start the car, dead battery, well its been sitting a while, get it started with the jump pack and the idle is really rough, why? It is running on 3 cylinders... It back fires and runs really ****ty. I actually disassembled the distributor to see if I could get more timing but no go, so I am wondering if I put it back together wrong. Any ideas what to look for? I noticed that the ground plug on the distributor is unhooked and there is no ground wire. There is also no ground wire from the valve cover either.... could it make the idle that bad and misfire etc... Thanks

[1991S13]

I don't know if the ground wires would cause a bad idle, but they are there for a reason so I would hook them back up.

Start with scanning the ECU to see if it's throwing any codes, here is how: http://www.240sx.org/faq/articles/ecmcodes.htm

I would do a basic tune up (plugs/wires, rotor and cap, o2 sensor, clean the AIV) then see how it is running.