jmead Posted July 17, 2003 Share Posted July 17, 2003 OK, this is how it works. I'm getting pretty annoyed, car doesn't work, and I don't know how to fix it. I've posted a few threads, but I've just been getting the same replies. I've very thankful for everyones help, but I figure if I add some incentive maybe I'll get some more suggestions and some more detailed responses. Basically, the person who tells me how to fix my car gets $10. If there are multiple variations of the same suggestion, the person with the most detailed and informative response gets the prize. $10 (or more, depending on how much help I need to get this going) will be awarded through either paypal, or via $10 money order. My problem: Car doesn't run right, and often, at all. It used to run a little rough, backfire occasionally during hard acceleration off-idle, but now it is much worse. I've replaced the AFM (twice), both times with used units that were supposed to work, but none of the 3 I've had in the car have been tested with any other. I've also eliminated the possibility of a vaccum leak (I think), the hose between the AFM and intake is fine, no holes, rips, and I've replaced the clamps. I'm also fairly confident it is not a ground issue. I've tested everything with a multimeter and everything seems to be grounded to everything else. It used to not start at all. Last time I tried, it would start after alot of cranking, idle very roughly, ocasionally backfiring out of the intake (blew the intake hose off once, could see the flame), and then die. If I give it gas, it just backfires more, but sometimes it will rev up all the way to redline and behave as it would normally, and then go back to sputtering. Car is a 76 280z, K&N filter, no other mods (yet). So, what could it be? Wiring to the afm (how can I check/fix this?), timing, ECU problems? Let me hear your ideas Quote Link to comment Share on other sites More sharing options...
David K Posted July 17, 2003 Share Posted July 17, 2003 Check your fuel pump, then TPS, head temp sensor (if equipped),.......ECU Quote Link to comment Share on other sites More sharing options...
rags Posted July 17, 2003 Share Posted July 17, 2003 Still sounds like a vacuum leak to me. Try removing the hose that goes to the top of the valve cover and plugging it. I don't mean the valve cover but the hose. You want to stop any air from entering the hose. This test will eliminate the crankcase as a source for a vacuum leak. Ya gotta start somewhere. Joe Quote Link to comment Share on other sites More sharing options...
stony Posted July 17, 2003 Share Posted July 17, 2003 ECU ECU ECU ECU (stony is chanting) i had this same condition happen to me when i was in japan except it was an L20 turbo in a skyline.... kinda intermittent i had no clue... i replaced the ECU and it was fixed ;> Quote Link to comment Share on other sites More sharing options...
denny411 Posted July 17, 2003 Share Posted July 17, 2003 I would definitely check your fuel pressure. How about the fuel pump relay? If it were bad or on the way out, it could cause such an intermittent problem.(mgb`s are notorious for this) The fuel filter would be the cheapest and easiest to replace first. If the car runs fine after you replace the filter, but then starts to run bad again, I would lean towards a rusted fuel tank. Next to check would be the pickup coil and/or ignition module in the distributor.(not sure if the 76 had a module in the dist?) It could still be a vacume leak as stated above. If so, the most obvious place to check would be the EGR valve, and then your brake booster. If they all check out , I would say the ecm has to be bad. If none of these fix your problem, My only recomendation would be to install a sbc withan automatic/manual transmission of your choice, a holly carb,msd ignition,and a fuel cell with a holly fuel pump and regulator. This should cover all the possibilities GOOD LUCK Quote Link to comment Share on other sites More sharing options...
jmead Posted July 17, 2003 Author Share Posted July 17, 2003 OK, thanks for the replies. I'll have a few hours to myself to go screw with the car ina little while, and I'll go try the suggestions. The fuel pump is OK, I think. I had a kink in the hose that went between the gas tank and fuel pump, but I found a 1/2" 90* hose connector and that solved that problem. I've cranked it over with the fuel line disconnected, and some fuel came out....I assume that means it is working. I'm not really sure if it was operating at 100%, all I was looking for was to see if it worked at all. Also, the filter was clogged, i think. I removed the filter and I'm using a straight piece of hose right now, just for testing. I'll be replacing the filter ASAP. Quote Link to comment Share on other sites More sharing options...
jmead Posted July 17, 2003 Author Share Posted July 17, 2003 IT WAS A VACUUM LEAK IN THE BRAKE BOOSTER! denny411 - you've earned yourself at least $5 for that! I hadn't even thought of the brake booster. I removed all the hoses and covered them, but same problem. I didn't see the point in trying the brake booster too, but I did....and that (pretty much) fixed it. There is still a problem though. Off idle it still backfires a little, and when I get very high on the tach (around 5-6k) it bounces all the way to redline and dies. When I turn the key off and back on, it does starts and runs fine, but it will do the same thing over again if I hit 5k (or sometimes lower, it has done the same thing at 3k before....just it happens almost everytime when I hit 5-6k) Any ideas? Does this sound like AFM? It does to me...but ECU sounds good too. Let me here those ideas. The problem is only half fixed (but that is a whole lot better than not fixed at all). Also...yeah, the SBC swap. That was the plan the whole time. Only not quite yet. I'm building up everything I need first. I've got the headers, fan, and I bought a chevy 350 and 700R4 (just haven't picked them up yet). My plan was to rip the engine out this winter when I couldn't drive the car anyway. But I also told myself that if I couldn't get this engine running again smoothly for under $100 I was just going to start the swap a little sooner. Quote Link to comment Share on other sites More sharing options...
Jwink25 Posted July 17, 2003 Share Posted July 17, 2003 Try looking at your TPS for your remaining problem. I had something like this happen to my Ford Probe GT. It turned out to be the TPS. It wasn't always sending the correct reading for some reason. The engine would stumble and even stall at times...then at other times run just fine. It always seemed to do it at about the same RPMS too. What I ended up doing was; taking it off, cleaning eveything, then putting it all back together...I adjusted everything just the way the book told me to. It is very important to get it just right. At least on my car. I hope this helps, Jason Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 18, 2003 Share Posted July 18, 2003 DELETE Quote Link to comment Share on other sites More sharing options...
denny411 Posted July 18, 2003 Share Posted July 18, 2003 Keep the $5 for the sbc fund. I hope you get the rest figured out soon. BTW, I suggest you get a fuel filter asap. If you have any loose rust or scale in the tank, it wouldn`t take long driving the car for some to make it`s way to your injectors. It`s next to impossible to clean rust from injectors. They would be much easier to just replace. Quote Link to comment Share on other sites More sharing options...
jmead Posted July 18, 2003 Author Share Posted July 18, 2003 I'm not sure about the igntion timing...I was figuring that somebody would suggest that (it make sense that the only way it would fire out the intake is a serious timing issue). I don't really know much about that area of my car. I've never had my dist open or off, still have the stock coil, same wires....etc. Any suggestion on what to check out specifically? And yeah, I know a filter is a good idea. The only reason I'm running it without a filter at all is because I just completely re-finished my tank (inside and out), and flushed all the lines of any old gas. I wasnted to eliminate as many potential problems as possible, filter seemed like a logical one. I'm pretty sure the TPS switch is correct. I've made sure it is set to idle when at idle...I can't be sure it is at WOT when its at WOT, but it must be close. The problem could be TPS I suppose, it just seems odd due to the nature of the problem, I think it dies at 5-6k no matter what, if I'm in neutral and steadily increase the throttle until its that high, or just a quick press, does it either way. Thanks for the suggestion, I'll check that. (I need two people though, so its going to have to wait for now) Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted July 18, 2003 Share Posted July 18, 2003 DELETE Quote Link to comment Share on other sites More sharing options...
Forrest Posted July 18, 2003 Share Posted July 18, 2003 I had the same problem with the tach bouncing around (not in time with rpm) right after revving to 4k, and then the car dying. It was caused by having too much play in the distributor shaft. After replacing the distributor, the problem was solved. Quote Link to comment Share on other sites More sharing options...
j260z Posted July 23, 2003 Share Posted July 23, 2003 if it is your distributor, which i think it sounds like, check out this site on how to rebuild it http://www.physics.ohio-state.edu/~jrdemers/280ZX/distributor/distribase.html Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted July 24, 2003 Share Posted July 24, 2003 My car had the exact same problem and still does sometimes. some of it has to do with your timing being too advanced but the other 70% i'm willing to bet money on it your fuel pump relay. put a pressure gauge on your car and drive around when you get your problem i bet your lacking pressure.. thas what mine did. hope it helps. Ed Quote Link to comment Share on other sites More sharing options...
jmead Posted July 29, 2003 Author Share Posted July 29, 2003 I guess I'm going to replace the dizzy with a zx model.... But there is some NEW INFO This is kind of strange...while I'm driving, esepically after accelerating, it will buck as I've said. This is when the gas pedal is released slowly to come to cruising speed. But, if I take my foot of the gas as fast as I can, IT DOESN'T DO IT! Why could this be? It almost sounds like a transmission problem to me.... I would think it should be worse the faster I decelerate, but that isn't the case... Any ideas? Quote Link to comment Share on other sites More sharing options...
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