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Alternator Noise with MS2


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The block or head can be an acceptable second choice, but sheet metal grounds are generally terrible. Grounding the ECU to the battery cuts out any potential for voltage drops with the block to battery ground.


I have not seen the starter cause a voltage spike that would be a problem with grounding the ECU to the battery but not the block.

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I also had issues with the LC2 and LC1.

Could you tell us which outputs you used from controller to ECU ? and Controller to gauge? Are they tied intogether? 

Have you selected the proper outputs from controller?

Have you tried to re-program the default outputs with LM programmer?

Are you getting solid green light on lc2 once on?

What are your tunerstudio settings for the Wideband controller?


Mind you its really easy to fry an LC2 controller I think mine went out while it was on I plugged in COM serial port. (later read thats NO NO ) 


Ditto on LC2 using the same heater and controller ground stupid design. The 14point7 units are perfect because they have separate grounds and the Spartan2 was made with mega squirt in mind has a neat way to recalibrate and getting more accurate readings between gauge and EMS. 


I also tell guys that got my wiring harness to ground MS at battery or block. Chassis ground could get weird especially the s30 chassis harness. 

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There is a debate by some Standalone ECU manufactures on using an engine ground ( Intake manifold or cylinder head preferred ) , or a ground from the ECU straight to the Battery terminal.  IMHO, there should be no debate at all.  There are dangers associated with grounding an ECU directly to the Negative Battery cable and those dangers should be discussed. 


The following  is why  Nissan, and most OEM manufacturers ( that I have ever seen ),  always ground the ECU to the engine Cylinder head or Intake manifold.  


1: It reduces the potential to create a Large ground loop. Large ground loops can increase electrical noise in the electrical circuit. ECU's and sensor operate on millivolts and they don't like Electrical noise.  Andy Wyatt has a good article on proper ECU grounding procedures. It is a very good article.  Andy Whittle who makes DIYAutoTuning videos ( very good videos BTW ) , has covered this same subject on Guild of EFI Tuners before. Their consensus is ground ECU to engine.. for a number of reasons. 




2: The #1 reason for not connecting the ECU ground directly to the Negative battery cable is what if the Main ground cable to the starter is defective or loose??? ... then you can absolutely FRY your ECU in an  instant when you crank the engine over. This happens more often than some people realise. 


A new starter motor draws between 150 to 200 depending on it's Power rating.  That's for a small 4 - 6 cylinder engine... under  ideal conditions ( Google it ). That's constant running, once they have gotten the engine spinning.  On initial start, momentary draw can easily be 250 to 300 amps on a V8 or High compression 6 cylinder. In freezing temperatures that momentary draw can rise to 500 AMPS!!!  That's a hell of a lot of current flowing through that Negative battery Terminal. Think about that for a bit. 


 Out main ground strap bolts directly to the engine block. In most cases to the Top starter mounting bolt that goes through the transmission.  Thiis connection has to be 100% perfect and be capable of handling up to 500 amps of momentary current. We also have a small 10 gauge wire that goes from the Negative Battery terminal to the Firewall. That handle maybe 40 to 50 amps maximum 


What happens if you change the starter or transmission and forget to attach the Negative Battery cable  to the engine . Or you leave the top bolt  a bit loose. Mistakes happen all the time when it's late and you're tired. Or there's a bit of corrosion, dirt, grease, oil , paint  or some other contaminant at the ground location for that Neg battery cable. Or perhaps the cable is old and fayed, or has some corrosion in the eyelet?  Happens all the time on Vintage cars.


 What will happen is that when you crank the engine, the starter is going to pull that 200+ amps through any ground circuit it can. If the starter main ground is not PERFECT... that means that it will pull some or ALL of that amperage through ANY other ground source. That includes the tiny #10 gauge wire to the firewall, throttle cables (  Common for them to catch fire as they get so hot ) or any other ground connected to the Negative Battery cable. And that includes your expensive ECU. There is no denying that. It has happened countless times in the Automotive world and is well documented.


That my friends is why I always connect my ECU grounds to the engine. You will not fry the ECU if something bad happens to the starter or the ground cable to the starter.  


 And as I've mentioned over and over. Nissan chose the engine grounding method for the ECU fir very sound engineering reasons. I'm not going to second guess them. Or the hundreds of OEM manufacturers who choose the same method.  Personally, I have never seen an OEM manufacturer ground an ECU directly to the Battery. Oh I'm sure that somewhere,  sometime an OEM has. And I'm sure  " Some guy " will have to dig up an example jst to try and prove otherwise.  Just my .02c. 







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BTW. I just e-mailed Shane Rice ( Op )  and he confirmed that he has indeed switched his ECU ground from the Chassis to the Intake Manifold. Stock Nissan grounding location.  So all is good in that respect.  I was remote tuning for Shane so this is all relevant to me. And I know some inside details on the setup.  The tune worked very well according to Shane. FWIW. 


The AFR gauge difference  all just a calibration issue with the Innovate WB controller. It's not a big issue and is a common problem with Innovate products. Personally, I have personally seen and read about too many issues with Innovate products and would never use one of their products.  


Innovate apparently shut down there User Support Forums in late 2016. To many negative comments. Is that lame or what? 



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Engine block ground is OK. Just as long as it is a reasonable  distance ( 12 inches??? )  away from Starter motor. Starter motor produces a huge amount of EMI when cranking. You don't want a sensitive ECU ground close by. Starter will also induce electrical Eddy currents in the engine block close to the starter. These dissipate with distance. 


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All of this talk about single ground points - engine block, intake manifold, battery negative, etc., whatever - as single points, is pointless.  It's the complete circuit that matters. Just be sure that whatever it is that you're powering (and by powering I mean current flow), has a good clean low resistance circuit.  It's a circle. 


If you think in terms of a circuit, then things like your injectors, and the ECU, and your AFR gauge, and your O2 sensors, and your alternator power circuit, and your battery charging circuit (which should be thought of independently of the starter power circuit although the wires might be in the same places), etc., will all make more sense.


You can have a fantastic, clean, large gauge wire ground to the intake manifold but if the manifold is not tied well to the block or the alternator of the battery or wherever you decide the current needs to start from and end at, then the perfect excellent contact with the intake manifold won't matter. 


You have to work out the complete circuit.  I think that much confusion is caused by the age-old practice of attaching the alternator power lead to the starter power lug, and the negative cable to the starter close to it.  The starter cables are so big that they draw all of the attention. 

Edited by NewZed
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