akumazedex Posted March 15, 2009 Share Posted March 15, 2009 Hi all, I picked up an '82 280ZX N/A a few weeks ago, however there seems to be a little problem, it seems to have a slight to moderate misfire. I replaced all the plugs wires cap and rotor, I have good spark on all cylinders. I replaced all of the injectors with little change. Cylinder #3 seems to be the culprit. I ran a compression check on all cylinders and they turned out to be within specs all within 5 PSI, from what I can remember 130-170 PSI, give or take some. The mis seems to be most obvious at low RPM, below 3K or so, after that it seems ok. Heres what i know about the car, it has a rebuilt motor, i confirmed that. I peeked in the cylinders an the hone marks look brand new. When i bought the car, it came with turbo injectors, they seem factory, they were old so i replaced them. The valves sound a little noisy, could use an adjustment. I was given advice by two people so far, First, run some fuel system cleaner and see if it cleans up, maybe some carbon build up on the valves. Second, check the valve clearance to see if they might have too much play possibly not opening the all the way. Thats all that i can remember. Any help would be great. Quote Link to comment Share on other sites More sharing options...
Shawn MacAnanny Posted April 4, 2009 Share Posted April 4, 2009 Ever fix the problem? I am having the same issue with my 78 Quote Link to comment Share on other sites More sharing options...
akumazedex Posted April 5, 2009 Author Share Posted April 5, 2009 not really, it did get better tho.. it only cuts out when its cold and that is only for the first few minutes. Haven't got a clue. I've been thinking it might be a coil, I have seen some weird stuff at work happen like that. It also seems like it might be something like a crank sensor, but I dont know where the computer gets a crank signal, theres nothing that seems like a crank sensor on alldata or in the factory manual. You could check out those. Mine completely cuts out for a split second when its cold and then runs like nothing happened. What does yours do exactly? Maybe we can try some stuff. Quote Link to comment Share on other sites More sharing options...
Shawn MacAnanny Posted April 5, 2009 Share Posted April 5, 2009 Well i ordered some Caig DeoxIT but its backordered. Im going to try cleaning all of the connectors on the car. I am also going to buy a new AFM just to have a spare to 'tune' with. I have a dual wideband setup for my Firebid so i think im going to drill and weld an 02 bung to the exhaust and use it to tune this car since the AFM can be adjusted. I want to have an extra to be able to revert to if i mess it up. I'm going to buy a new coil today since mine looks very old, and order my cap and rotor since those 3 things are less than $40 and wont hurt it. My cap looks old, the rotor does but the car has new plug wires, new plugs, rebuilt head, new ECT, new connectors on the coolant sensors, new fuel filter. I am going to bump my idle timing up to 20degrees since my vacuum advance doesnt work. I had it advanced up to 25 with no change in idle quality so i figured the error lies somewhere else. One i get back from work im going to be testing all of the sensors i can. I put some injector cleaner in the tank (Guaranteed to pass emmissions cleaner) which ive found to be the absolute best, even better than seafoam for cleaning injectors. I've only run it about 10 minutes with 93 octance but it seems to have slighly helped the idle quality but there is still a major issue with it. do these cars have crank sensors? I have a mechanical distributor that fires my plugs. I'm not sure how the injectors know how ot fire though. I think i might spray down all my connectors with the cheepo electric parts cleaner i have until my DeoxIT gets here. Quote Link to comment Share on other sites More sharing options...
Shawn MacAnanny Posted April 6, 2009 Share Posted April 6, 2009 I took the AFM off yesterday and its not testing right. I have no reading from the IAT, and i lose reading when the flap opens, and pin 6 does really give me any readings so i am pretty sure its bad. IT took it apart and it all looks fine cleaned it a little but to no avail. Quote Link to comment Share on other sites More sharing options...
Shawn MacAnanny Posted April 6, 2009 Share Posted April 6, 2009 Ok well im an idiot haha i thought my meter was auto rang finding for some reason i didnt have the settings at the right values and rather than reading error or anything my meter just displayed infinite as if it werent connected at all. Stupid meter. The AFM seems to check out ok. I ordered another last night anyway. I'll compare the two and see how they check out. Quote Link to comment Share on other sites More sharing options...
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