Guest Death69 Posted December 31, 2006 Share Posted December 31, 2006 hi all! i just purchased my first Z today for what i believe to be a steal! (78 280z, minimum rust and STILL RUNNING for 275!) The problem is that the car starts good and all, but it sounds like one of the cylinders isnt firing. i believe that its just bad injectors but am not sure. there is a exhuast leak and was told by somone that could cause bad valves or something. i just wanna know what else to consider just incase it isnt the injectors. all helps appreciated! Quote Link to comment Share on other sites More sharing options...
Ledphoot Posted December 31, 2006 Share Posted December 31, 2006 could be as simple as a burned plug or bad plugwire. Start there. Leak will burn a valve sometimes so fix it quickly as well. Quote Link to comment Share on other sites More sharing options...
cpt jack Posted December 31, 2006 Share Posted December 31, 2006 If thers an exhaust leak check where the exhaust manifold hits that down pipe before the cat... mine snaped in half... take like 10 min to weld back up... 2 other guys i know said thats where theyer leak was... and when i got my z i kinda had tha same problem... check all plugs they can tell u alot about how its running... Quote Link to comment Share on other sites More sharing options...
Guest Death69 Posted December 31, 2006 Share Posted December 31, 2006 could be as simple as a burned plug or bad plugwire. Start there. Leak will burn a valve sometimes so fix it quickly as well. how would i know if the valve has been burned? right now at start up its sound fine, then there is a pause, and then it sounds fine again. it does this about 3-4 times before it starts to idle normally. and the acceleration isnt good at all Quote Link to comment Share on other sites More sharing options...
SHADY280 Posted December 31, 2006 Share Posted December 31, 2006 id start with the simple stuff, dont sweat it yet, do a tune up, get a good base, heck could even be a clogged fuel filter. and get that exhaust fixed, it could get into the car and you could also become dizzy, plus you can hurt the engine. and if you not sure, get a fsm or haynes manual Quote Link to comment Share on other sites More sharing options...
sweetleaf Posted December 31, 2006 Share Posted December 31, 2006 Pull all your plugs and post a picture of them. Make sure to remember witch cylinder each one came from. You can use a noid light to make sure all the injectors are getting a pulse. I'd also put a fuel pressure gauge on it. Run a compression test. No reason to start throwing expensive parts on, until you identify the problem. Quote Link to comment Share on other sites More sharing options...
cpt jack Posted January 1, 2007 Share Posted January 1, 2007 Pull all your plugs and post a picture of them. Make sure to remember witch cylinder each one came from. You can use a noid light to make sure all the injectors are getting a pulse. I'd also put a fuel pressure gauge on it. Run a compression test. No reason to start throwing expensive parts on, until you identify the problem. Yea u know one thing u might really want to duble check???? The afm where the intake hose goes over it... mine came loose and it ran like ♥♥♥♥ kept dyin... Quote Link to comment Share on other sites More sharing options...
Guest Death69 Posted January 1, 2007 Share Posted January 1, 2007 Yea u know one thing u might really want to duble check???? The afm where the intake hose goes over it... mine came loose and it ran like ♥♥♥♥ kept dyin... hmm actually that might be it. the guy i got the z from had duct-tape right ever it. i wont have my z back until saturday (tires were f***** up and i didnt want to risk a blow out on the freeway) but when i get it back ill check all the things you guys reccomended. Quote Link to comment Share on other sites More sharing options...
waynekarnes Posted January 2, 2007 Share Posted January 2, 2007 exhaust leak will only cause a burnt valve if you have a leak big enough that you can see it, you get the engine over heated and when you shut the engine off, it's freezing outside. there is enought heat in the head to keep the valves warm. with engine running at idle, pull spark plug wire off plug number one, does idle change, does miss go away ? no ? put the wire back on. repeat through spark plug number 6. when you pull the wires, idle should get worse, more missing. if you find the wire that doesn't make a difference, that's most likely the dead cylinder. check for spark at the end of the spark plug wire. with engine running, hold end of wire to ground ( engine block, head, ect ) DO NOT use the battery as ground. you should hear the tack tack sound of spark hitting the ground. if you do this at night, turn off your trouble light, in the dark you should see a white/bluish light. if no spark, or a yellow spark, you have an ignition problem. good spark ? yes ? let's eliminate the spark plug. swap spark plug from good cylinder to nonfiring cylinder and bad to good cylinder. put wires back in place. start the engine. you may still have a miss. if so, pull spark plug wire off what was the good cylinder, does it make a difference, starts to miss ? yes ? then wasn't the spark plug. put wire back on the good cylinder. pull wire from bad cylinder. does engine stumble or runs the same, still has the miss ? if so, sounds like a fuel/air problem. which could include a bad valve, but not likely on the datsun 6 banger. before you go tearing anything apart, add full bottle of techron injector cleaner to the fuel tank. the no name cheap crap is mostly kerosene and alcohol and some sort of moth killer. open the air cleaner cover, with engine running spray 1/2 can of injector cleaner into the tube leading towards the induction system. drive 100 miles or so. spray other half can of the injector cleaner towards the induction system. put 20, 30 miles on. if still have a miss, then start into the fuel system. Quote Link to comment Share on other sites More sharing options...
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