luvmy280zxt Posted May 30, 2008 Share Posted May 30, 2008 Hows it going everyone! I own a 81 zxt. it sat for 6 months while i was on deployment, but ran fine b4 that. The day i got back i started it up and it ran fine, but on day 2 it started acting up. When i first start it up it idel's very low and seems like it wants to die. Once i tap on the gas it reves up and idels fine. When i sit there and rev up the motor it hangs at about 2200 rpms and struggles to go up. I have to do this a few times to get it to completely rev up to higher rpm's. The other prob. is while driving, when i give it gas and am at a higher rpm like 4000 it starts to shudder and looses power. Ive changed a few things and im stuck. I called Power freaks nissan in portland OR. and they said its my mass air flow sensor. The said it was that when i told them that a backfire noise came from it when ever i reved it up when i was under the hood. PLZ help!!!!! I love my Z and have poured a lot of cash into it. Im to the point where im might have to get rid of it or put it on hold for a while. Thanx Quote Link to comment Share on other sites More sharing options...
nando280zxt Posted May 30, 2008 Share Posted May 30, 2008 My zx used to do the same thing, and i know its a common problem. I would try checking your spark plugs, wires, connection to the ECU and injectors. Maybe use a fuel injector cleaner. Try replacing the cap and rotor. Since its been still i would put my guess on an electrical problem. Also check the head temp sensor! I'll try to find you the ohm readings, im sure someone on here has them though. Hope that helps! Quote Link to comment Share on other sites More sharing options...
280zx 2by2 Posted May 31, 2008 Share Posted May 31, 2008 was the backfire and actual pop back fire or just like a , well its a hard to describe sound...kind of like if the extra fuel in the exhaust didnt ignite all at once but burned slowly my car sounds like the second one but that still dosent explain your RPM loss mabe your cat burned up? check and see if exhaust pressure is different... good luck. Quote Link to comment Share on other sites More sharing options...
roger.svoboda Posted May 31, 2008 Share Posted May 31, 2008 try pulling all the connectors apart in the engine compartment especially the afm and tps. Check for corrosion and clean as best you can. Long shot but easy to check make sure your battery cables are clean both ends and free of corrosion. If someone put those one size fit all clamp connectors on there get rid of them soonest. Check to see that the ground was not cut off and run direct tothe starter it is supposed to jump to a bolt below the battery box and then to the starter. is the boost gage working and you know the turbo is spooling up? check your fuel pressure maybe something happened in the fuel delivery system just sitting around. Quote Link to comment Share on other sites More sharing options...
nando280zxt Posted May 31, 2008 Share Posted May 31, 2008 Im willing to bet its backfiring through the intake. Am i right? Quote Link to comment Share on other sites More sharing options...
luvmy280zx Posted June 1, 2008 Share Posted June 1, 2008 Im willing to bet its backfiring through the intake. Am i right? yea its a no kidding back fire through the intake. It did it again 2 day after i changed 2 fuel injectors. the car starts up ok but when i rev it up it still hangs at 2000 rpm and it will do that for a bit then bang, a back fire out of the intake or actuall the MAF. how can i tell if my turbo is bad? Quote Link to comment Share on other sites More sharing options...
luvmy280zx Posted June 1, 2008 Share Posted June 1, 2008 My zx used to do the same thing, and i know its a common problem. I would try checking your spark plugs, wires, connection to the ECU and injectors. Maybe use a fuel injector cleaner. Try replacing the cap and rotor. Since its been still i would put my guess on an electrical problem. Also check the head temp sensor! I'll try to find you the ohm readings, im sure someone on here has them though. Hope that helps! i actually did all of that and its still doing the same thing. Im gonna change my MAF and see if that fix's it. if that dosent fix it ...im stuck! Quote Link to comment Share on other sites More sharing options...
luvmy280zx Posted June 1, 2008 Share Posted June 1, 2008 was the backfire and actual pop back fire or just like a , well its a hard to describe sound...kind of like if the extra fuel in the exhaust didnt ignite all at once but burned slowly my car sounds like the second one but that still dosent explain your RPM loss mabe your cat burned up? check and see if exhaust pressure is different... good luck. SUP, well i dont have a cat anymore. i hollowed it out due to a massive build up of carbon. it was an actual pop sound from the MAF. Quote Link to comment Share on other sites More sharing options...
nando280zxt Posted June 1, 2008 Share Posted June 1, 2008 idk man. mine used to do that, but its something that came and went. i did a tune-up one day, changed the plugs, wires, cap and rotor, never happened since. but i know exactly what you are talking about. I really think its a fuel/ spark problem. this sounds dumb but i want you to try it and tell me what happens. turn your car on, and then disconnect the connection to the head temp sensor, that should send a signal to the ECU to make the fuel injectors to maximum duty cycle. then rev the engine and see how it runs. In theory it should run like crap, but in your case it may just work. Quote Link to comment Share on other sites More sharing options...
luvmy280zx Posted June 1, 2008 Share Posted June 1, 2008 idk man. mine used to do that, but its something that came and went. i did a tune-up one day, changed the plugs, wires, cap and rotor, never happened since. but i know exactly what you are talking about. I really think its a fuel/ spark problem. this sounds dumb but i want you to try it and tell me what happens. turn your car on, and then disconnect the connection to the head temp sensor, that should send a signal to the ECU to make the fuel injectors to maximum duty cycle. then rev the engine and see how it runs. In theory it should run like crap, but in your case it may just work. ok, ill try it. favor though....where is the head temp sensor at exactly. Still new to the wonderful world of Z cars. lol thanx bro! Quote Link to comment Share on other sites More sharing options...
nando280zxt Posted June 1, 2008 Share Posted June 1, 2008 its on the side of the block where the battery is. i think its under the second and third spark plug i believe, about six inches below or so. Its a sensor plugged into the block. you can't miss it. remember turn your car on first, or else it won't start if you disconnect the sensor. Quote Link to comment Share on other sites More sharing options...
luvmy280zx Posted June 2, 2008 Share Posted June 2, 2008 ok i disconnected it. it ran until i tried to drive it, then it stalled. I re-connected it and its still doing the same thing. I drove it around town a bit hard and it was backfireing pretty hard from the MAF. It seems like the engine is loosing pwr cuz of that? any tips? Quote Link to comment Share on other sites More sharing options...
luvmy280zx Posted June 2, 2008 Share Posted June 2, 2008 So where in washington r u? Im in oak harbor. Quote Link to comment Share on other sites More sharing options...
nando280zxt Posted June 2, 2008 Share Posted June 2, 2008 yea i was just wondering how it would run on full duty cycle. Well...i don't know what else to say? I really think its a fuel problem. Possibly spark. That being said its time for me to take the hat off and step back for someone with some more knowledge than i have. Quote Link to comment Share on other sites More sharing options...
woldson Posted June 2, 2008 Share Posted June 2, 2008 Though this dose not completely fit your engine it will enlighten you greatly on how the fi system works on your car. Search efi bible. Read it and search some more on various compondants, this will allow us to maby give you a better answer. Quote Link to comment Share on other sites More sharing options...
DuoWing Posted June 9, 2008 Share Posted June 9, 2008 Have you removed the kick panel on the driver's side to uncover the ECU? Unplug the ECU harness connectors and plug them back in. While driving if the problem happens try shaking the wires. I had a problem for a while where the car would run fine as long as I drove with light throttle and kept the RPMs under I believe 3000 or 3500 it was something along that. Anything over the car would start to lose power, and it would struggle to make it to the higher RPMS, below it was fine. Under hard throttle/boost it would start popping. Just like you're saying. I found that when this would happen I could reach down and give the ECU wiring a good shake and then the car would start running as if nothing ever happened. The car would run good for a while then all of a sudden act up again. I removed the grounds from the intake manifold cleaned them up, and then tightened them back down. This seemed to fix the problem for a long time, eventually it showed up again. Nismopick clued me in on what seems to be the issue. It's the 2 ground wires that come out of the ECU. They go into a crush connector that connects to 3 other wires that becomes the main ECU grounds. I cut this out and redid the connections and I've never had problems again. Things even seemed to run smoother. Quote Link to comment Share on other sites More sharing options...
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