CarJway Posted November 24, 2003 Share Posted November 24, 2003 well a few weeks ago i stated how my car ran perfect on fuel injector cleaner. So i thought it was the injectors and so did a million other people. Changed them this week end and guess what... Still have this werid studder... The idle is fixed. But i will be driving... hit 2k and it dies... rpm's still climing then 3k comes around and it kicks in... hits 4k then dies and comes back at 5k. I feel like driving this car into a wall... maybe the car gets lean and that would explain the studder.. but im guessing and don't want to keep changing crap that isn't broken. Any suggestions would be greatly appreciated... Quote Link to comment Share on other sites More sharing options...
datsunlover Posted November 24, 2003 Share Posted November 24, 2003 Sounds like the computer is shuting down the engine. There is a "limp" mode that the computer will go into if ANY of the sensors/fuel injectors go out of whack (no signal, wrong signal, whatever) and sometimes it will turn on and off while you are driving if there is an intermitent problem. This happened to my 75 280 back in the summer, and I agree: like driving into a wall! My car actually got to the point that it would idle PERFECT but would not go at all: try to take off, and it would sputter and die. I unhooked the Throttle positon sensor, and 'forced' the computer to stay in limp mode. This way, it would rev to about 25-2800 RPM and then cut out. (I know I know, not better) BUT, it was drivable. I would say... check the AFM. Run the checks on it, make sure the contacts are clean, and especialy check the FI conectors and harness. (seing as you changed fuel injectors recently) Hope this helps! Quote Link to comment Share on other sites More sharing options...
CarJway Posted November 24, 2003 Author Share Posted November 24, 2003 How would i go about checking AFM ? I installed new injector harness's also... because the old one broke off because they were all brittle and crap. So I went ahead and changed those two. But what i don't understand and is why the damn car runs perfect with the fuel injector cleaner. But once that crap runs out, in like 30 min. the car goes back to it's stupid self... Quote Link to comment Share on other sites More sharing options...
Guest 240hybrid Posted November 25, 2003 Share Posted November 25, 2003 You most likely already did this, but I would check all the sensors...even if they're hooked up. Pull the plugs off the sensors and see if their corroded, and put some Di-electric (spelling??) grease on them and plug them back up. If you have those male/female connecters here and there inbetween the harness and sensors/plugs, check them too. I would check all the grounds too, cleaning them up and making sure they're getting good contact, and maybe run a few extra grounds also. As for checking the AFM that is a good idea like datsun lover mentioned, and do a continuity check using a ohmmeter. If you don't have a Factory Service Manual, I would suggest getting one, you'll see them on ebay every once in a while and this site http://www.zparts.com sells them too. You may be shocked at the price, but they're worth it. The FSM has save me plenty of times and I find it has a great deal more info. than a crappy haynes manuals. It'll tell what each wire/prong on the AFM and ECU harness goes to and what to do to check it. You can do a continuity test on the ECU also, and this is how I found that the thermo-time sensor was causing my NA L28 to run way rich and stumble a while back. I looked at the ECU plug and started scratching my head, but it's really not that difficult. A FSM will walk you through it. Chase Quote Link to comment Share on other sites More sharing options...
innerware Posted November 25, 2003 Share Posted November 25, 2003 you can also get a manual from Courtesy Nissan in Texas. They sell them on CD and they are text searchable. You will spend the same amount on it as a real book but this allows you to print out just what you want and who cares if you get grease on it. Good luck, at least you have new injectors and harnesses, it is a start. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted November 25, 2003 Share Posted November 25, 2003 If you don't have the FSM (or cant get one for a while for some reason) let me know and I can scan and send you the afm checks. You will need a multimeter and some test leads. (one of the checks requires 12V to be aplied across 2 terminals and the air flap moved to check resistance on 2 other terminals) One thing.. my book is for a 75 280z. I think it's the same afm all the way to 78, but 79+ is a newer/diferent afm. let me know man. Quote Link to comment Share on other sites More sharing options...
David K Posted November 25, 2003 Share Posted November 25, 2003 Carjway and all, check out this thread, http://hybridz.org/phpBB2/viewtopic.php?t=20890&highlight=tps Quote Link to comment Share on other sites More sharing options...
CarJway Posted November 27, 2003 Author Share Posted November 27, 2003 hey guys thanks a lot for your help! i didn't think i would get so much feed back! Well i tried taking the TPS sensor off and that didn't really fix it... it had a rough idle and still wouldn't rev. But i just noticed something when it starts to studder, the RPM's bounce around and stuff... werid... *datsunlover* hey i would really appreciate if you could scan that for me.. I took the ohm/volt meter from work so is thier anything else i could check with this.. i herd something about setting up the TPS with a voltmeter or something. Oh and just in case i didn't mention this is a 78 280z. Quote Link to comment Share on other sites More sharing options...
datsunlover Posted November 27, 2003 Share Posted November 27, 2003 Ok, I'll try to get those scans off to you tonite man. As for that thread David posted there, my car ran the same. And all the others who had the dredded "poping and sputering problem" had problems around 2500 RPM: The factory set 'cut off' for the limp mode I mentioned earlier. The AFM is usually the culprit, next is the TPS. If those two check out, its ignition or wiring. (I was told this by an older Nissan mechanic who remembers working on these cars when they were 3-5 years old!) Anyway, I'm out for now. i'll email you later on. Quote Link to comment Share on other sites More sharing options...
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