oxbloodboots Posted March 4, 2007 Share Posted March 4, 2007 Hello Everyone, My name is Sam and this is my first post. Been reading the forums for 2 or 3 years and own 4 zcars. I read so many questions that are quicly responded by strong encouragement to run a search as the subject has allready been addressed, so i tried my best to do my homework. I have a stumper and have been browsing everyday after work for 2 weeks. All that being said..... HELP! Found a rough running 82 280zxt for $1000. Needed a harmonic balancer, an injecter for #2 cylinder, a MAF sensor and plugs. Replaced them all with the parts I had laying around. Now have backfire on 3 cylinders into the intake and it refuses to idle at all if I can even get it started. I checked; firing order, injector order, injectors, computer, MAF, EGR, distibutor, optical crank sensor in the ditro, relays, fuses, fusible links, compression, leak down, valves for sticking, radiator splint, flex compasitor, etc.. I am out of ideas. Any suggestions would greatly appriciated. Sam P.S. I even had a mobile mechanic come by, take my $50, then tell me he didn't know anything about Z cars and suggested I find someone that did. Quote Link to comment Share on other sites More sharing options...
veritech-z Posted March 4, 2007 Share Posted March 4, 2007 Have you checked the orientation of the distributor drive gear? If the oil pump has ever been off, it's probably that the shaft was not put in the correct way. Quote Link to comment Share on other sites More sharing options...
oxbloodboots Posted March 4, 2007 Author Share Posted March 4, 2007 i have had that problem with the distro before and did check it, but thank you for the suggestion. Quote Link to comment Share on other sites More sharing options...
sweetleaf Posted March 4, 2007 Share Posted March 4, 2007 Give us numbers for compression, fuel pressure, timing, etc.. Then we can help you better.. Quote Link to comment Share on other sites More sharing options...
oxbloodboots Posted March 4, 2007 Author Share Posted March 4, 2007 about 90 psi on all six if i remember. dont have a tester for fuel pressure, but checked the pump, filter, and visually inspected the flow at the rail(looked fine). haven't touched anything with timing since it ran, but will look tonight when i get bak and post when I get a chance. again, thanks for the response. Quote Link to comment Share on other sites More sharing options...
twoeightythreez Posted March 5, 2007 Share Posted March 5, 2007 90 psi cranking compression is quite low. Are you holding the throttle wide open when you're doing the comp test? I hope you're not because if you're doing it right your motor is definitely in need of some wrenching. See if it goes up after adding a tablespoon of oil to the cylinders. If compression goes up you gotta re-ring it. (obviously if your compresson is even your head gasket is OK...unless some space-time warpage paradox caused ALL SIX cylinders to blow....lol) Ignition timing that is off would not give you low compression, but a cam that 's off a tooth will, possibly the chain is that loose? It's easy to check by removing the cam cover with engine at TDC. There's a groove on the cam thrust plate that should index with a notch on the cam gear. (not to mention if it jumped you will FEEL the looseness in the chain) I would bet the P.O. tried re-clocking the dizzy to try to compensate for out-of-phase cam timing meself. Check your valve adjustments for sure though...engine should have at least 130psi with no cylinder less than 75% of the highest cylinder. (if your max is 130 your lowest can't be less than 103..this being for a daily beater motor. A performance car should have no cylinder being less then 90% of the highest, as in if 130 is your highest you better not see lower than 117psi.) 90, though....is too low no matter how even it is from cyl-cyl.) just my .02 Shoot...my TURBO motor pushed 160psi cranking comp. If it only didn't burn oil.....carbon helps compression though Who knows? possibly the P.O. rebuilt the engine and didn't put the chain on right! That would kinda be like winning the lottery...... Quote Link to comment Share on other sites More sharing options...
VinhZXT Posted March 6, 2007 Share Posted March 6, 2007 Most back firing problems are caused by timing problem. I bought an 81 280ZXT from a junk yard awhile back. The car went thru several auto repair shops and finally it ended up in the junkyard. None of the shops can get this car running. They thought it was a bad computer. I brought it home and played with it for a few hours and found out that the chain some how was off by 1 tooth. It is pretty easy to check for the timing. Just open the valve cover and turn the crank and watch for the shiny link matching up with the dot on the sprocket when it's at TDC. If the motor is at TDC and the shiny link is not lining up with the dot on the sprocket then you need to wedge the chain, remove the cam sprocket bolt and turn the cam so that the dot will line up with shiny link. Reinstall the sprocket. Note: when the chain is off by 1 tooth my compression tests were still all good at 140s. Good luck Quote Link to comment Share on other sites More sharing options...
oxbloodboots Posted March 7, 2007 Author Share Posted March 7, 2007 Thanks everyone for your help. I sure feel like an a$$. I was playing with it again last night trying to get it to idle long enough to listed for which cylinders were backfireing and a 6" flame shot out of number 6 injector hole. I immediatly knew the problem. I pulled off the fuel rail and found that the o rings on the last 2 cylinders were binding and kept the last 3 injectors from completely seating. All the screws were in and snugged and to the naked eye everything looked right. But sure enough, after i replaced the o-rings and reseated the rail, it fired right up and purrs like a kitten. Thanks for the support, Sam PS I rechecked and do have 120psi on all 6. Quote Link to comment Share on other sites More sharing options...
CalifaThugz Posted March 11, 2007 Share Posted March 11, 2007 I too have the same problem! Except my car isn't turbo and my car sucks at idling too its like revving and stuff before it idled perfect at 750 rpm and now it jumps from 750 to 1500 and when ever I turn my car on it gets annoying because I keep hearing a popping noise on the intake I was like WHAT THE FUDGE!? It does that every time now... AND one injector keeps on popping out it broke 3 freaking screws already its a big dragg going to my parts car (its like 30 miles away from my house) and getting new ones. I got so tired and I finally got an idea I came to ask at hybrid Z because everybody is an expert here!:burnout:I was going to do a SR swap soon but I hear these engines can pull 450 hp plus and I wanted to hit that and go above it probally. But with the budget of a 14 year old cuz I am one. Quote Link to comment Share on other sites More sharing options...
oxbloodboots Posted March 18, 2007 Author Share Posted March 18, 2007 i am by no means an expert, are all the injectors stock and did you check ohms on them(about 2.5 - 3 on stock nissan injectors)? i would go part by part on the fuel system; injectors, regulator, filter, pump. then i would check timing and vacuum. Best of luck, sam Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted April 5, 2007 Share Posted April 5, 2007 Thug: If you haven't already fixed it, the problem screams firing order to me. Did it just start doing what you're describing or was it after you did something to it like change spark plugs or change the cam? Quote Link to comment Share on other sites More sharing options...
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