Ive read most the grounding threads-
And ive done everything except the pressure sensor.

In the FAQ grounding how to-
It says brown wire with black stripe.

Well I have an 87 and have no such thing.
Theres 2 black wires, with brown "patches".
Is that the ground?

Thanks.

 

Unless the turbos are different, and I'll look at the schematics as soon as this is posted, there IS NO ground for the boost sensor...The ECU provides the grounds for the boost sensor, AFM (except door switch), TPS, atmospheric pressure sensor, water thermo sensor, and intake air temp sensor...These unit are not grounded individually for a reason...Adding a ground to any of these components CANNOT help, only hurt, the systems in question...

 

All right, turbos are the same, except for the knock sensor wiring. Br/W is your 5v ref, Br/R is your ECU & boost gage output, B/W is your 12v power supply, and the black wire is the "common potential" ground for all those sensors, but it is NOT grounded to the chassis until the ECU gives it a ground. It amazes me you guys haven't fried more ECUs than the couple I hear about. PLEASE research the schematics before you go grounding things, if you can't make sense of them, give me a hollar, I've been reading them for 20 years (mostly on aircraft, but cars are very simple animals compared to a modern aircraft, and the only difference between the two is the power supply voltage)...

 

Well- I understand the ECU grounds all these sensors- but what happens when the ECU ground is ineffician?
Or corroded, brittle, bad?

Why would grounding it at the device instead of the ECU hurt anything?
If anything it has a shorter path to the battery ground.

 

I just re assembled everything, and my car is running like crap.
Idles around 1500 and drops to 1k and dies. Runs great other then that.

Sounds like I have a vacume leak somewhere (whooshing sound), but I have gone over everything. Mabey its my belt squeaking or something.

I dint ground the PS yet- I want more input- im seeing more and more people do this and get good results.

 

If the original ECU ground is shot, replace it, but use the same electrical pathway, don't create a new one...

I tried to explain yesterday in another post why Mazda set up these grounds (through the ECU) the way they did, I'm not typing it all again...

Your not worried about a shorter path to ground for these sensors- the ECU, however, is worried about the exact same ground potential for them, due to the low voltage signals. That's why it's designed the way it is.

The car obviously ran fine when it was new, with the factory grounds- give it "new" grounds again, in the original locations, by giving the terminal a good clean metal-to-metal contact with the chassis. Some sanding will be required, but that's the extent of labor involved.

If adding a new ground wire seems to be fixing a problem, then your OEM ground is bad. Being that most of the original grounds are used for several components, grounding just one of them is not actually fixing the inherent problem, and may make it worse down the road...

 

See I agree with that?

If the mazda designed it like this, then it has a purpous.

Im going to clean the ECU ground and call it good.


Looks like my intercooler hose it shot- allowing a HUGE leakage.

 

There was a thing called a factory service bulletin that dealt with this. You can find all the factory service bulletins from a place called ALLDATA.COM.

That factory service bulletin has been copied and posted on this site by......me, before. Search. Hee, hee.

 

Searched and read.

Hurm. Looks like its time for a new ground.