Effects of poorly grounded MAF

What are the effects of a poorly grounded MAF?

I am still having MPG problems, so decided
to check the MAF grounding...

I checked the earth potential difference between the middle pin
and a ground on the block... It had 17mV of difference...
too much, so I am going to put an earth strap on it.

Im confused though...
If the reference(ground) to the sensor is too high, then the output
voltage will read high.
Thus the ECU will think there is more airflow to the engine than
in reality. Therefore the ECU puts in more fuel than required, and
stuffs my fuel economy........

BUT, surely this is where the O2 sensor kicks in and leans out the
mixture. Perhaps the MAF has priority.
Not sure... Any ECU programming GURUs out there???

Anyone confirm my suspicions?
Basically I want to know what problems a poorly grouded causes...
I will update the results of re-grounded MAF.

LATER

The basic effects of a badly grounded MAF is the engine running like a 1960 Mini cooper - i.e. wandering, no power, crap economy, sounds like a bag of spanners, etc, etc.

Voltage measurement is relative between the ground pin and output pin: therefore if your output pin is reading 5v and ground pin is at 0v, then the ECU thinks it sees 5v. If, however, the ground is at 17mV, then the ECU sees 4.983V, not 5 (5v - 17mV). It may not sound much, but bad grounds cause all sorts of problems, few of which are actually related to dc voltage - current loops, emc pickup, frying ECU's (oh yes indeed), etc, etc...

The ECU doesn't adjust for economy, it adjusts for the best drive. It tries to balances a lot of different inputs - some on short time-scales, some on long time-scales. The o2 sensor is a long-timescale measurement - i.e. the ECU will gradually adjust to suit over a length of time.

Fuel economy is also a balancing act between getting every possible tune-up item correct. To be honest, anything can cause bad economy - including the oil filter!

If you want any more information, let me know, but it gets horribly complex for here on in...

I think* my O2 sensor isn't grounded properly (or MAF maybe...)

Where do i connect the voltmeter on either the O2 / MAF to check potential difference? Whats the expected difference on both?

I've recently fried my ECU (and now replaced it) - so..... whats the best way to ground the MAF and the O2 sensor? (once i find out which is the problem).....

-Phil

Have a look here:

http://primeraweb.homeip.net/problems.html

the question is... how did my o2 sensor ground go BAD..... without having all the other wires connected with my O2 sensor(sharing the SAME bad grounnd near the cat convertor) have a bad ground too??.

i thoguht the o2 sensor was part of a big wiring harness conneected to ground at the catalytic convertor?

but the question is..... how did everything else NOT go bad?

AHHHHHHHHH!

BTW.... whats best solution to ground the items?

http://www.se-r.net/engine/maf_ground.html
This guy used gold sodder and soddered a 10 gauge wire (after splicing the white grounnd wire). Why not use crimps? Any advantages/disadvantages?


-Phil

I am about to re-ground my MAF, and will certainly not be
using solder!

Solder is for cool, low current places like Circuit Boards etc.
How or high current enviroments require lugs or crimps.
Once done correctly these will not come loose, unlike solder
that can softern, snap, break, etc.

Do you solder the wires in your home wall socket? NO,
you use screw clamp connectors.
Why because of it faults or gets hot, a solder joint could
break..... DANGEROUS.

I am going to try and replace the clip in the MAF
socket, and just crimp the two wires into there.
Else, cut the white wire and put an inline crimp
to include the new grounding wire.

SO yeah USE CRIMPS/LUGS.

EEYORE:

Cheers for the info on MAF and MPG.
I have checked O2 sensor, airfilter, and replace plugs.
THe MPG problem is major, so I thought it might be the O2.
I think the MAF could have a major effect, but I also think the 20W50
runnning in it will be hampering the economy, both from more
friction and pumping up the lifters.
I cannot wait to re-ground the MAF and see if it fixes the problem.

Later

Which is the ground wire on the O2?

White middle one, same as the MAF? or one of the sides (theres black and red ...... as opposed to 2 oranges like the MAF)

-Phil

STOP!

There's only been bad ground instances with the MAF, not the o2.

As far as I'm aware, the o2 sensor DOES NOT HAVE A GROUND WIRE!!!! It takes voltage input, sense output and is grounded via the engine.

Whether you use solder or not is your decision, but I can say this: normal lead solder is perfectly adequate for this work.

Fair enough, the wires on your plugs at home aren't soldered, but this is for ease of use, not because of current concerns. "A properly made solder joint will carry more current than the wire it is supporting". Just think about it, molten lead versus multi-strand low-grade copper wire. Seriously, the only reason everything on the planet isn't soldered is because is cheaper and quicker to use crimps.

The trick to soldering is to make a mechanical connection with the wires, then just use the solder to hold that mechanical connection and provide good contact. A solder connection will only break if it's either badly done, or the mechanic connection wasn't made.

Hope this helps.

Yeah I agree that solder is adequate.

But, based on electrical standards, and the good
practice of manufacturers the world over, I
would use lugs/crimps.
Nissan recommends replacing the metal pin within the
MAF plug, I am just going to put an inline lug in.
Look under the bonnet of any modern car and you will
see they use solder only on circuit boards, everything
else has a clip, lug, crimp etc.

Eeyore do you know if the MAF can have a major
effect on the economy of an SR20?
The cost pf poor MPG is not so much the issue
anymore, I just have to know what is causing it.

Any comments/hints/tips would be great.

LAter

The reason solder isn't used in cars is because of modern production techniques. The wiring looms are made by robot outside of the car, then robot assembled. It's quick and consistent, unlike a monkey with a soldering iron. To be honest, the best possible connection is a crimp connector that has been soldered! If you were considering high-quality audio, then the solder/crimp decision becomes important, but for this it really doesn't matter.

The MAF will have an effect on the MPG. The MAF is used by the ECU to determine the driving conditions and therefore adjust the tuning as necessary. Air flow is directly related to injector rate. This ratio does, however, change throughout the driving range, so could not be considered proportional. For example, going up a steep hill will requires large amounts of air, but a relatively low speed. It's very different from motorway driving.

In other words, if your MAF is playing up, you WILL see a decrease in your MPG.

Quite how much and when purely depends on the current driving conditions. There probably won't be a huge difference on motorway runs, but town driving, race driving and steep inclines would be severely affected.