Guest vodkaboy Posted May 1, 2003 Share Posted May 1, 2003 well, i originally thought my Z was misfiring/backfiring because i was runing freaking rich with a leaking injector (and had proof by how badly i failed DEQ), but now that i have a new injector and have passed DEQ with flying colors, i have to look elsewhere to find what is wrong. when the car is under load, especially while accelerating or going up hill, it pops and studders until around 3000rpm and has less power than it should until 3000 rpm as well. it will not do this when i have the throtle closed, only when i open it up a bit (i havnt noticed that it does it any worse at WOT or half throtle or anything. it seems consistantly the same regardless of how much im on the gas, unless i am not on the gas at all) i have also heard that the ignition, specifically the advance, on this generation of zs is a piece of crap, could that be causing this? info on the car: stock '77 280Z, EFI Quote Link to comment Share on other sites More sharing options...
Mike C Posted May 1, 2003 Share Posted May 1, 2003 Popping out the intake? Usually a sign of running too lean, at least on carbureted cars. Popping out the exhuast most likely too rich. I would check fuel pump performance and the status of your filter. Quote Link to comment Share on other sites More sharing options...
nullbound Posted May 1, 2003 Share Posted May 1, 2003 i'm actually having similar problems with my '78 280 daily driver. it idles fine, but giving it gas gets the pops and stutters until it's revved past 3000 rpms. it accelerates fine if i floor it all the time. normal driving, or anything in traffic, and i get popping through the intake. i had to richen my fuel mixture quite a bit and advance the timing to get it to run better than it was. but, it's still not great. i was planning on replacing my vaccuum lines... one of mine, (the one that runs from the charcoal cannister to a 't,' and then to the throttle body and distributor) is dry and hardened and seems slightly suspect. i'm hoping that's the problem in my case anyway.... any other suggestions would be greatly appreciated. Quote Link to comment Share on other sites More sharing options...
MAYHEM Posted May 1, 2003 Share Posted May 1, 2003 vodkaboy, did you find out your problem? did you already do a test on your fuel regulator? Quote Link to comment Share on other sites More sharing options...
Guest vodkaboy Posted May 2, 2003 Share Posted May 2, 2003 vodkaboy, did you find out your problem? did you already do a test on your fuel regulator? havnt done a test on the regulator. i got a local shop around me to test the injectors because i have heard it can get messy (at least if you do it the way i was told), and one of them was leaking, which caused the problem to be worse, almost undrivable, and also caused me to have a lot less power (not to mention it caused me to fail smog). when i got a new injector in there, the problem was still there, just not as bad, and i had quite a bit more of my power pack, although its still not where it should be. since i passed smog after i got the new injector, i dont think that i have any more leaks, but its still poping and not running right. Quote Link to comment Share on other sites More sharing options...
David K Posted May 2, 2003 Share Posted May 2, 2003 Guys, unplug your throttle body positioning sensor on the side of the throttle body. its the little black box. take her for a drive and see if it feels any different. Anytime im having problems before 3k and it clears up right after it passes 3k, its the tps. Quote Link to comment Share on other sites More sharing options...
Guest vodkaboy Posted May 2, 2003 Share Posted May 2, 2003 Guys, unplug your throttle body positioning sensor on the side of the throttle body. its the little black box. take her for a drive and see if it feels any different. Anytime im having problems before 3k and it clears up right after it passes 3k, its the tps. and if that is the problem, what can we do to fix it? and wouldn't that make it run odly anyway, or would it run without the weirdness before 3K? would like a bit more information on this. Quote Link to comment Share on other sites More sharing options...
David K Posted May 2, 2003 Share Posted May 2, 2003 The tps moves back and forth with plate int he throttle body. It tells the ECU when you are WOT, so it adds more fuel to the engine at that time. it does not hurt to take it off or unplug it at all. unplug it, and take the z for a drive. Go ahead and WOT that engine. Its ok. If it runs better, then replace your TPS. Quote Link to comment Share on other sites More sharing options...
nullbound Posted May 2, 2003 Share Posted May 2, 2003 i replaced the vaccuum lines on mine last night and it helped some, but it's still not exactly right. it still gives the stutters and pops. i know that one of the lines was leaking now and am glad to get that out of the equation. i'll do the check you suggested david for the tps. thanks for the tip!! Quote Link to comment Share on other sites More sharing options...
Guest vodkaboy Posted May 4, 2003 Share Posted May 4, 2003 well, i disconnected the TPS and all i saw was a slight drop in responsiveness, and a lower rougher idle... problem remained the same, if not maybe even worse... any other ideas? Quote Link to comment Share on other sites More sharing options...
fl327 Posted May 4, 2003 Share Posted May 4, 2003 if it was still popping when you disconnected tps, it might be the afm. problems associated with a L motor that wont rev past 2500 or so is usually the tps, and its the cheapest thing to go after first, i had that same problem on my zxt a while back and it was indeed the tps, it had a pop pop pop at or after 2.5k, pulled off the tps, and it would give me a little more rpm, put in a new tps-Problem solved. have you messed with timing, i know if i mess with mine too much, it will backfire and pop to no end. i would say go for the tps, go to your local junkyard and grab a few try that out, and remember you do have to adjust it, youre supposed to use a voltimeter, but i just adjust it on the fly i think its easier. remember to clean that tps connector on both ends until its squeaky clean. if its not that. i would check timing same time as tps. then check the afm, possibly replace it and see if it clears things up, that backfire and popping coming out of the intake is giving the afm some pain, thats for sure. Quote Link to comment Share on other sites More sharing options...
Guest vodkaboy Posted May 4, 2003 Share Posted May 4, 2003 its poping in the exhaust, not out the intake (to the best of my knowledge, it soudns like its popping in the downpipe/under the floorboards). i havnt messed with the timing, but the car was siting for 4 years... i dont think that that would mess up the timing, but you never know. i might take a timing light to it later then (need to get another one, because mine inexplicabily died). i have heard that the ignition, specifically the advance, on classic Z's is a piece of trash, so i might check up on it as well (just need to figure out how to). Quote Link to comment Share on other sites More sharing options...
fl327 Posted May 4, 2003 Share Posted May 4, 2003 oh shoot, i thought this was a turbo zxt or somethign ok, try to replace to the dist. then with a zx/maxima single pickup dist with the e12-80 module. that may do it, and check the timing. Quote Link to comment Share on other sites More sharing options...
MAYHEM Posted May 5, 2003 Share Posted May 5, 2003 its popping in the exhaust' date=' not out the intake (to the best of my knowledge, it sounds like its popping in the downpipe/under the floorboards). I havnt messed with the timing, but the car was siting for 4 years[/quote'] My I just bought has the same problem. it was sitting since '99. I noticed through troubleshooting that I have very little spark on 3 cylinders. I can remove the no# 3,4, and 6 wire with very little change in the RPM. She will run mind you at idle ... O.K., but leaning on the gas she sputters and backfires (rich) out the tailpipe. This the reason my '77 is trying to a diesel impersonation. I'm going to knock out a tune-up first. I'll let you know if I find anything else, vodkaboy Quote Link to comment Share on other sites More sharing options...
nullbound Posted May 5, 2003 Share Posted May 5, 2003 thanks for putting me on the right track, david karey!! i disconnected the throttle position sensor on my car and noted zero change. however, when plugging it back in, the problem went away. the switch itself wasnt bad, but the connection to it was. when i reconnected, i actually pushed the plug in a little farther than it was, as well as wiggled it a bit. i disconnected the switch again and cleaned the terminals on the switch itself, as well as the plug. i also put some dielectric grease on the terminals. the problem was that there was some corrosion on the terminals that was preventing a good connection with the tps. problem solved in my case!! i dont think the car has run this good since 1978 thanks again! Quote Link to comment Share on other sites More sharing options...
Guest vodkaboy Posted May 8, 2003 Share Posted May 8, 2003 well, i recently started cleaning various electrical contacts, and in a couple of places, one im assuming is the manafold air temp sensor (sensor on the top of the intake manafold), and im not sure about the other (to the rear of the intake manafold), they were literally corroded to the point that it turned a clean toothbrush green with oxodized copper powder, and all around the female end was a thin coating of green powder... havnt been able to drive it yet, as the clutch is far gone, and i need to do that this weekend, but i will tell you how it goes now that my sensors all have clean contacts... Quote Link to comment Share on other sites More sharing options...
MAYHEM Posted May 9, 2003 Share Posted May 9, 2003 well' date=' i recently started cleaning various electrical contacts, and in a couple of places, they were literally corroded to the point that it turned a clean toothbrush green with oxodized copper powder, and all around the female end was a thin coating of green powder... havnt been able to drive it yet, as the clutch is far gone, and i need to do that this weekend, but i will tell you how it goes now that my sensors all have clean contacts...[/quote'] I'm in the same boat, vodkaboy. Invest in a set of jeweler files to clean the contacts. Worth the investment. Also electical cleaner and a can of di-electric grease. I just (10 minutes ago) drove my '77 for the first time since 99. I've been chasing a butt load of corrosion, cleaned up most of the backfiring. It's not perfect, I think a timing issue now, but I can't find the timing mark on the pulley. Quote Link to comment Share on other sites More sharing options...
MAYHEM Posted June 8, 2003 Share Posted June 8, 2003 Guys, unplug your throttle body positioning sensor on the side of the throttle body. its the little black box. take her for a drive and see if it feels any different. Anytime im having problems before 3k and it clears up right after it passes 3k, its the tps. Ok, DK, here is my issue. I drove my car for the first time since 1999. The car runs truly great. BUT it will protest/backfire at the intake from a standing roll to about 2500 after that it's smooth as silk. I've the gas tank draiing and tune up. I tend to feel it's a lean issue. Is the TPS the ONLY thing it can be? Also that plug on the side of the AFM for the mixture setting its it that important? I'm missing mine. Will it allow air in without it ? Thanks Quote Link to comment Share on other sites More sharing options...
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