niner11 Posted September 5, 2007 Share Posted September 5, 2007 I've been having problems with a crappy idle and noticed something tonight. Before the ms install I converted my externally regulated voltage regulator to a zx internal one. That being the case you sometimes need to rev the engine a little off idle for a second to get the car to charge. I noticed tonight that the idle was pretty good until the alternator came on line and then it was stable but sounded like a miss. The first part of the datalog is just on battery voltage and at about 1488..... or so I think you can see the battery volts go above 12.2. That's where the idle begins to deteriorate. Is this just a noisy alternator or is something else obvious going on here? I've only had this thing running a day so I thought I'd ask before I went out and bought more stuff for this install. Thanks for any ideas you guys might have. alternator noise demo.zip Quote Link to comment Share on other sites More sharing options...
z-ya Posted September 5, 2007 Share Posted September 5, 2007 The battery voltage looks fine. As long as it is above 11V or so, the MS will work fine. Disconnect the alternator, and put a batter charger on the battery. See how it runs with the alternator disconnected. Quote Link to comment Share on other sites More sharing options...
niner11 Posted September 5, 2007 Author Share Posted September 5, 2007 Thanks for taking a look. On the datalog about half of it is on just battery voltage and then I rev the engine a little and the alternator comes online. That is when the volts go from about 11 to almost 13.... and the idle starts to suffer. I have a few condensers to install and I was wondering what side of the coil to install one of them on. Also one for the alternator. Thanks, Chuck Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted September 5, 2007 Share Posted September 5, 2007 For what its worth, I finally received my 10amp 12volt noise filter. I got it on ebay. It's about 1"x 1" x 1.5" made by Pioneer. I put it inline with the power feed to the MSII per Pete's suggestion. It's too soon to say for sure but so far, so good. I haven't had any strange boot issues with the MSII like I was having before... http://cgi.ebay.com/9-NEW-OEM-PIONEER-POWER-NOISE-FILTERs-10a-FUSE-INLINE_W0QQitemZ190149722791QQihZ009QQcategoryZ58036QQssPageNameZWDVWQQrdZ1QQcmdZViewItem Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted September 5, 2007 Share Posted September 5, 2007 Also check your voltage/opening time compensation for the injectors. That could effect your idle. Your AFR would tell you what's going on if the actual injector PW is changing with voltage. Quote Link to comment Share on other sites More sharing options...
Dave Posted September 5, 2007 Share Posted September 5, 2007 Another good indication of a alternator problem is to check for AC output at the battery. If you get .9 AC and below that is fairly normal, but a reading of 1 volt and above would indicate a breakdown with the diodes. The other thing to look for is the ground wire from the alternator case. Connect the volt meter set to DC from the negative side of the battery to the alternator case. If there is a reading its not properly grounded. Quote Link to comment Share on other sites More sharing options...
niner11 Posted September 5, 2007 Author Share Posted September 5, 2007 Both Dave's thanks. I just put a meter on the battery and it shows .015 to .025ac while charging. When measuring the case to the neg side of the battery I get .015 dc. Cygnusx1, I have been changing the tps/map dot threshold values to make sure that interference doesnt trigger accel. Seems to be smoothing things out a little. As for noise suppression, I will try a variety of filters and condensors and see what happens. Quote Link to comment Share on other sites More sharing options...
z-ya Posted September 5, 2007 Share Posted September 5, 2007 Pull the two wire plug off the alternator, and see if the problem goes away. If that has no effect, disconnect the large wire form the alternator. If the alternator is the source of the problem, this will identify it. Also, what size are your injectors? Are you using PWM or series resistors inline with your injectors? If at 12V, the injectors are not opening all the way, but providing the right amount of fuel for a good idle, then when the voltage increases, the injectors may open all the way, making it run too rich. Quote Link to comment Share on other sites More sharing options...
Dave Posted September 5, 2007 Share Posted September 5, 2007 Both Dave's thanks. I just put a meter on the battery and it shows .015 to .025ac while charging. When measuring the case to the neg side of the battery I get .015 dc. There is nothing wrong with those readings. The diodes are working fine and there is a good ground at the alternator. Quote Link to comment Share on other sites More sharing options...
niner11 Posted September 5, 2007 Author Share Posted September 5, 2007 Thanks everybody. I will isolate the alternator like z-ya said. Currently running 32lb high impedance injectors. On my last datalog (from a little while ago) it was the voltage that seemed to vary a bunch even when the alternator was charging. Btw, the car runs great. I'm really happy with the install and appreciate all of the help that I've gotten over the last 6 months or so. For right now I've limited boost to about 10lbs. here is what i'm running: 280zxt using an 82 dizzy wire per moby's/diy's instructions for MSII t3/04e .63ar (will not fit without a spacer) 32lb injectors/pallnet fuel rail at 45lbs a pete down pipe from this board 240sx tps Quote Link to comment Share on other sites More sharing options...
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