MJLamberson Posted January 23, 2008 Share Posted January 23, 2008 so heres what up, a friend of mine drives a 76 280z that was running fine for a while but now runs like crap, and it only runs on 5, so there is no action in #6, he has good spark, fuel to and through the injector but nothing happens, this problem goes away and then comes back... the injectors are getting power... for a while I was thinking fuel pressure but why would that only affect #6, also, he has a new fuel filter... any tips on where to look are greatly appriciated Quote Link to comment Share on other sites More sharing options...
alexideways Posted January 23, 2008 Share Posted January 23, 2008 How old is the ignition wiring? Where is it routed? Check for cracks or worn spots. Also, here's an hill billy trick, if you have a timing light. You hook the timing light to cylinder #6, you route the light's wires trough one of the inspection lids and bring it inside (if length permits it.) or tie it to one of the wiper arms. Drive the car around until the fault occurs, when it does, check the timing light to see if it fires consistently. If it does, check the wiring for the injectors or fuel system. If it blinks erratically, you know you have a fault in the ignition system. Quote Link to comment Share on other sites More sharing options...
MJLamberson Posted January 23, 2008 Author Share Posted January 23, 2008 we dont have a timing light but the ignition system is fine, well, it looks fine anyways... Quote Link to comment Share on other sites More sharing options...
chrism Posted January 23, 2008 Share Posted January 23, 2008 I would swap the spark plug wire with one of similar length if possable. Also, you could swap the injector with another one to see if the problem moves. How do you know it's piston #6 if you don't have a timing light? Quote Link to comment Share on other sites More sharing options...
MJLamberson Posted January 23, 2008 Author Share Posted January 23, 2008 we changed the injector a few times with no change, same thing for the wire, we know its #6 because when we unplug that injector or pull that spark wire nothing changes, if we pull any other one the RPM drops and it runs worse, with the #6 nothing changes, its our culprit Quote Link to comment Share on other sites More sharing options...
chrism Posted January 23, 2008 Share Posted January 23, 2008 Put a noid light on the injector and make sure it is blinking when you crank the car. If it does not blink. You are not getting any current flow through the injector. You will still see 12v at the injector but it will not pull low to ground through the ECU. That could be a bad ground or problem with the ECU. Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted January 23, 2008 Share Posted January 23, 2008 Have you checked for voltage and/or trigger for that injector? It's hard to tell from your initial post if you mean that the injector for #6 is actually firing or not, kinda sounds like it is. If there is fuel and spark for sure in #6, then I would look at the valve train. I believe these engines use a cam follower and a hydraulic lifter to provide proper pre-load. If my understanding of these engines are correct the oil pump is at the front of the engine, and so the #6 lifters and cam ournals for that matter would be the last to get oil. I would look at the oil, how old/is there enough? Is the pressure good? Filter condition? Quote Link to comment Share on other sites More sharing options...
MJLamberson Posted January 23, 2008 Author Share Posted January 23, 2008 the injector is getting power and works fine... This is really confusing me, and when its running the injector clicks and the spark plug sparks... Quote Link to comment Share on other sites More sharing options...
chrism Posted January 23, 2008 Share Posted January 23, 2008 I would do a compression test. See if you have wind in the sails. Or at least see if the compression is consistant while the engine cranks. I would do a wet and dry test. Make sure there isn't a drastic change in compression between each test. Quote Link to comment Share on other sites More sharing options...
MJLamberson Posted January 23, 2008 Author Share Posted January 23, 2008 we did a compression test and double, then triple checked it, compression is fine, oil and filter are newish, as to the valve train thats out of my league, I guess we will to have it looked at, oh and my very knowledgable auto shop teacher cant figure it out eather Quote Link to comment Share on other sites More sharing options...
chrism Posted January 23, 2008 Share Posted January 23, 2008 Man, Wish I was there to see it. It's hard to work on a cars from thousands of miles away. As for the weak lifter. I used some slick50 hydraulic lifter restore to fix a problem in the past . The lifter was not building enough pressure to push the valve. That stuff work great. It goes in with the oil. Do that as a last ditch effort before taking the valve train apart. I would think you could see that problem with the compression test though. Good luck. Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted January 23, 2008 Share Posted January 23, 2008 Did you pull the sparkplug to make sure its not defective? Pull your cap and make sure there are no carbon tracks anywhere to indicate a bad cap/rotor. Evan Quote Link to comment Share on other sites More sharing options...
MJLamberson Posted January 23, 2008 Author Share Posted January 23, 2008 yes sir, spark plugs and caps are as good as new, we even tried swapping parts from my 77 (which is running fine) we temprarily swapped (or tried new) injectors, plugs, caps. still no action in #6 Quote Link to comment Share on other sites More sharing options...
alexideways Posted January 23, 2008 Share Posted January 23, 2008 Try to borrow a timing light from school, the little trick I gave you is THE easiest way to find out what quits when the cylinder goes dead. If the light keeps on flashing steadily, you know you have a fuel problem and if it stops flashing or skips a few flashes every now and then, you know you have an ignition problem. It takes out 1/2 of the variables off the equation... Quote Link to comment Share on other sites More sharing options...
MJLamberson Posted January 23, 2008 Author Share Posted January 23, 2008 ok Ill see if we have one at the shop tommorow, thanks for the tip. Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted January 23, 2008 Share Posted January 23, 2008 If your tech class does not have a timing light you need to donate some money to the school LOL. Good luck dude. Quote Link to comment Share on other sites More sharing options...
MJLamberson Posted January 23, 2008 Author Share Posted January 23, 2008 well we do have two lifts, one being indoors, so our school isnt short on money Quote Link to comment Share on other sites More sharing options...
Guest TeamNissan Posted January 23, 2008 Share Posted January 23, 2008 Your friend is the one who posted on the z/zx group on myspace? If so there seems to be more to the original story like the fact he is using the wrong injectors to begin with and that cylinder 4 was the original problem. He states he would take the plug wire off cylinder 6 and there would be no change in rpm so how can the ignition be "fine"? I'm not ragging and I'm sorry if thats not your friend but trust me its the ignition system. Quote Link to comment Share on other sites More sharing options...
MJLamberson Posted January 23, 2008 Author Share Posted January 23, 2008 I didnt know he posted his problem anywhere and Im not sure about him useing the wrong injectors, care to link me so I can see if its him? Quote Link to comment Share on other sites More sharing options...
Guest TeamNissan Posted January 23, 2008 Share Posted January 23, 2008 http://forum.myspace.com/index.cfm?fuseaction=messageboard.viewThread&entryID=51861835&groupID=100004208&adTopicID=2&Mytoken=FDE26826-DA8D-423F-A04D88A1589FDB2C45551976 Again sorry if I'm wrong but the location, year, model, problem are all the same. Quote Link to comment Share on other sites More sharing options...
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