lifegrddude Posted April 25, 2005 Share Posted April 25, 2005 Well, I'm on a 1/2 hour break for my classes and figured I would post about a recent problem that seems to be getting worse. It's something to do with the top harness that plugs into the ecu. Lately, under boost the a/f gauge will go lean and the car will have no power or sometimes ping. If I play with the harness some (it's random, I just wiggle and mess with the wires), I get lucky and the a/f gauge will read rich like it's supposed and the power will be there. Sometimes this problem will completely cut the power out and make the car stall while driving. I'm wondering if anyone knows which pin could possibly be giving me problems as it seems this issue is getting worse because the lean/no power condition happens every time I drive, unless I play with the harness. I don't have my FSM with me right now, (it's my parents' house) but I'd really appreciate some help, even if it means I have to splice some new wires into the harness or find some junkyard turbo harness clips to replace the ones on my Z. Quote Link to comment Share on other sites More sharing options...
BayAreaZT Posted April 25, 2005 Share Posted April 25, 2005 Get some electrical contact cleaner and clean the contacts. If that doesn't work you might want to look for any bent or loose pins. Quote Link to comment Share on other sites More sharing options...
VinhZXT Posted April 26, 2005 Share Posted April 26, 2005 This problem happened on both of my 280ZXTs. I ended up getting the 300ZXs ECU plugs and splice in and cured the problem. This was after countless times of cleanup the connectors and put conducting grease to them. Problem still intermittent so I replace the plugs altogether. You might want to openup the ECU to check for crack around the solder joints. I've seen crack in the solder joints around the pins which could cause this problem and may not be the plug itself. Good luck and let us know what you find. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted April 26, 2005 Share Posted April 26, 2005 clean them with electrical contact cleaner and then put some dielectric grease on the them, which will GREATLY help keep them from corroding. Quote Link to comment Share on other sites More sharing options...
lifegrddude Posted April 27, 2005 Author Share Posted April 27, 2005 Thanks for the info everyone, I'll look into this problem over the weekend and hopefully get it solved, but with the semester winding down it might be ~mid-May before I enough time to take things apart and examine them closely. VihnZXT- were the 300zx harnesses a direct swap for the wires, or did you have to rearrange the order of them at all? Also, were the harnesses from a turbo or n/a Z31? I'm just curious as I know I can easily find a 300zx in the yards, a turbo 300 will be a little harder to find, but the 280zxt's are getting rare here in San Diego. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted April 27, 2005 Share Posted April 27, 2005 dude seriously, cleaning the connections and putting some dielectric grease is like a two minute job... Quote Link to comment Share on other sites More sharing options...
VinhZXT Posted April 28, 2005 Share Posted April 28, 2005 Bastard// yes clean and grease it is 2 minutes but 5 minutes later it will spits and sputter again.. Trust me I know.. I got the plugs from a non turbo 300ZX. They are direct fit. The only one thing is you have to cut up your 280ZXT plug to get 1 or 2 pins out and plug them into 1 of the 300ZX plug. Sorry I forgot which one. You can do a comparision between them and you will see a couple of missing pins from the 300ZX plugs. There are more wires on the 300ZX so some wires will not be used. Good luck Quote Link to comment Share on other sites More sharing options...
lifegrddude Posted May 4, 2005 Author Share Posted May 4, 2005 I tried the contact cleaner on Sunday and drove the Z yesterday, but it was still sputtering and bucking under boost. Well, today I worked as fast I could to get out of my lab/internship and go to the local pick-n-pull. I got a harnes out of a 300zx like you suggested Vinh, and swapped it in. Lo and behold, the lean boost, saggy power condition is gone! WOT throttle reads rich on the A/F gauge and the power is nice. I have some mild detonation under high boost mode, but I think that has to do with the AFM setting, plug gap, or maybe the fpr setting. I'll deal with that later, so for now I will just use the low boost setting on my ProfecB. Thanks a bunch everyone for the help and suggestions. It's been close to 4 months since I've been able to floor it and not lose power. Quote Link to comment Share on other sites More sharing options...
Afshin Posted May 4, 2005 Share Posted May 4, 2005 when you say you swaped the harness with a 300zx one, do you mean you cut the wires before the ecu connectors ans soldered them to the 280zx harness vs. switching the entire harness.... Quote Link to comment Share on other sites More sharing options...
VinhZXT Posted May 5, 2005 Share Posted May 5, 2005 That's great.. I am glad you fixed the problem. Trust me I 've been thru that road before and you can't describe the feeling. For the running lean under heavy boost you may want to loosen up the AFM spring a few tooth at a time and test drive it. Again I 've seen this problem before with my ZXTs also. I was trying to save on the MPG and increase the AFM spring. On normal driving condition it was fine but when under boost and WOT about 12PSI it leans out. The good thing was I mark the wheel inside the AFM before I changed it. So I put it back and it was back to normal. Good luck.. PS. I've seen quite a few of the 280ZXTs ended up in the junkyard just because of the ECU plugs were bad... Many many and many shop would never ever find out this problem. lol.. They would think the ECU was bad or the AFM etc.. Now you know lol.. Oh yeah don't forget to check your timing too.. I just realize you are from San Diego. I went there for work several times at the shipyard near Gaslamp. Next time I go there for business I will give you a yell and you can give me a ride in your Z and show me around San Diego . lol... Quote Link to comment Share on other sites More sharing options...
lifegrddude Posted May 12, 2005 Author Share Posted May 12, 2005 Sorry for the delayed response. Afshin- yes I just cut the harness before the ecu connections for the 300zx harness and inserted new pins into the 300zx harness since it needed 3 wires to complete the transfer. I plan to do the 300zx ecu upgrade this summer sometime though. Hopefully the summer intern people won't kill me with extra hours. I will probably be asking you a lot of questions when I begin that project since some of the pictures in the sticky no longer work. lol Vihn- Thanks for the other suggestions as well. I'll see if any of those are the problems as soon as finals over (next Thursday). I will be changing out the head gasket soon (and most likely do the 300zx ecu upgrade at the same time) this summer since I think I saw an oil stain coming out from the #4 cylinder, and my coolant overflow goes dry every 3 weeks. If you do stop by San Diego, let me know, the first round is on me haha. You're more than welcome to hang out here anytime! Quote Link to comment Share on other sites More sharing options...
VinhZXT Posted May 12, 2005 Share Posted May 12, 2005 lifegrdude, My future mod will be doing the Z31 ECU swap also. I hope you didn't cut all the unused wires from the Z31 connectors..lol.. You will need them for the Z31 ECU swap.. I will let you know if I go to San Diego.. Take care Quote Link to comment Share on other sites More sharing options...
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