I just finished my MAF regrounding, I used 16ga wire soldered to the middle white wire. Then I ran it over to the negative battery ground where it bolts to the chassis. My question is this when we ran the car and tested how good are new connection was it read -001, is that really good or really bad?

You need to ground it to the same point that the ECU is grounded to otherwise you'll get ground loops which can cause more problems than the ones you're trying to fix (and hence the negative voltage reading).

Really? I ran my MAF reground to the firewall, and mounted it to just behind the ABS computer and pump. Voltage went from 14mv to 0.2mv.

Only reason I did this, is I couldnt find the proper grounding point, so I just grounded it to where it was supposed to go anyway (the firewall).

Havent had any more problems as of yet.

I grounded mine on the ground points on the intake manifold. Worked great for me.

i grounded to a bolt on the thermostat housing, i guess it worked for me...

I grounded mine to the mysterious plug thats on the distributor, seems like the perfect place.

Originally posted by tissue
Really? I ran my MAF reground to the firewall, and mounted it to just behind the ABS computer and pump. Voltage went from 14mv to 0.2mv.

Only reason I did this, is I couldnt find the proper grounding point, so I just grounded it to where it was supposed to go anyway (the firewall).

Havent had any more problems as of yet.


Okay, I'll change my response - you 'may' have problems due to ground loops if you ground to a different location.

The ECU is grounded to the engine block at the intake manifold near the throttle body (from memory - forgive me if I'm wrong) and all voltages are referenced from that point (see the FSM). If you ground somewhere else, like the car's chassis, there could be a difference in the ground potential between the two points which will offset your MAF reading. This offset can change with changing electrical loads (defogger on, headlights on, etc).

IOW, just because your reading is low, it may not be correct. You can see from his measurement of -001 that something is not right.

Taken to the extreme, why not ground it to the negative battery post? Or maybe the question should be why didn't Nissan ground the ECU to the firewall or the negative battery terminal?

Good analog data acquisition circuitry layout dictates a single ground point.


Tissue - what do you mean by "so I just grounded it to where it was supposed to go anyway (the firewall)." Where is this documented?

It says in the MAF reground procedure that you are supposed to ground it to a screw located near the firewall? I dont remember if it is on the firewall but.

I did see two ground screws underneath the throttle body that I thought may have been it, but they seemed too small (there were only 1-2 wires running to them, and they were tiny wires).

Who knows why Nissan has run grounds the way they have. It might be that they needed to run thick wire all the way to the battery to ground the ECU. What would be the point in running this wire all the way to the battery, when it can flow through the chassis, which is already there? Isnt the shortest ground possible generally the best too?

My goodness. Those black wires certainly do cause confusion don't they.

Is it possible that the error tolerance of the meter is 001?

How could adding a second ground cause the original ground to become worse? If by re - grounding - the original ground was removed and the ground then changed to a different location it could prove to be less effective??

By the way I reground mine to the other black wires on the engine block.

ON the angle part of the intake manifold there are 2 10 mm bolts. There should be I think 3 different wires grounded there. If you look you will see that 2 of them are actually the same wire, just going to both posts. That I believe is were it is supposed to be grounded.

I reground my MAF to the negative battery terminal. I figured that was the best place, and it's not too far away. You can hardly notice the wire running under the air intake tube and back up the battery.

Probedude is correct. You want everything referencing the same ground. What the ecu thinks is ground is what you need to be grounding to. In this case thats the engine block, so thats what you need to be grounding to.

I re-grounded mine on the #4 intake runner on the lower set of grounds wires. It use to read .045mv now reads .001-2mv, major improvement!

But does the ECU actually receive any data from the ground? I thought it was all from the orange wires on the MAF?

how do i test to see if its working?

Originally posted by tissue
But does the ECU actually receive any data from the ground? I thought it was all from the orange wires on the MAF?

All it is, is voltage, and the ground is one part of it, and the postive is the other part. The ground does effect the final voltage thats obtained.
~Ryan

Originally posted by SENTRASER
All it is, is voltage, and the ground is one part of it, and the postive is the other part. The ground does effect the final voltage thats obtained.
~Ryan
Right. The ground is a reference. You want your sensor and the ecu to be using the same reference.

This weekend I'll be moving the ground just to be on the safe side, but the car does feel MUCH better with the new ground.

when you measure the mv's, is that AC or DC? i have a craftsman digital multimeter and i have no idea what to set it to!

Originally posted by nx2000racer
when you measure the mv's, is that AC or DC? i have a craftsman digital multimeter and i have no idea what to set it to!

DC :p