Grounded throttle body and MPG

Dubs, in particular.

 

OMG. Ground it. Ground it real good.

 

I've no interest in the mod, just trying to resolve the question from ETC(SS): whether or not it's grounded to begin with. S'okay? Guess this is a case where keystrokes don't convey your mood, lol. I'm not stressed that It's not grounded.

 

I wonder if its safe to assume that if its not grounded, there's a reason? Things like safety, and prevention of catastrophic detonation spring to mind.

 

Ok, so there are metal bolts holding the plastic manifold to the engine head. And there are other metal bolts holding the throttle body to the (other end of the) plastic manifold. That still wouldn't change the fact that

right?

I'm certainly not standing up as an advocate of the ground mod, but just allowing that one of the claims--the TB isn't already grounded via the manifold--happens to be true.

All the rest of the claims are about whether anything would be better if the TB were grounded, or if it would make any difference at all, and those are the claims I'm having more trouble with.

The thing I was hoping somebody with a multimeter could check would still be pretty easy if anyone had a Gen 3 and wanted to. I'd also recommend looking in a real Gen 3 wiring diagram manual, because pinouts could be all different from my Gen 1. But here's the basic thing that could be tested:

The two electrical things that sit on the TB are the ETCS motor and the throttle position sensor. The sensor (on Gen 1) has a 4-terminal connector where the 'ground' reference is pin 4. The motor has no ground reference at all - it is a two-terminal DC motor that the ECM drives in both directions to open/close the throttle, so neither side is grounded.

So this leaves one thing a multimeter could be used to check: unplug the 4-pin connector at the position sensor, and check whether the sensor's pin 4 even has any continuity at all to the mechanical attachment point of the sensor to the TB. If there is none (as I suspect), then there is no electrical case to be made for why adding a ground wire at that attachment point would make any difference at all.

In fact, now that I look at this closely in my Gen 1 wiring diagram, I see that Toyota has been pretty careful about isolating this ground. All the engine sensors have dedicated connector pins for ground using a brown wire (a different color than the white-with-black-stripe used elsewhere for general grounding), each with its own dedicated point-to-point brown wire all meeting back at one single point: staying with my Gen 1 example, that's splice point I7, in the instrument panel very near the ECM. Toyota worked pretty hard to avoid creating any ground loops in this design. You might be able to thwart their efforts by adding a wire at the TB, if there is continuity from that bolt to pin 4. But there probably isn't, so you probably can't.

In all likelihood, none of this will stop the OP from noticing improved throttle response.

-Chap

Just to say it one more time ... every wire color, pin number, splice point, etc. that I mention in this post is for example only and taken from a Gen 1 wiring diagram. Please be sure to look on techinfo.toyota.com for the Gen 3 diagram before poking at any Gen 3 wires....

 

Umm, I did that, reported back. To reiterate: there's no continuity between throttle body and the car body.

 

Umm, are you still sure we're talking about the same test?

After you checked the Gen 3 wiring diagram, which pin(s) on the Gen 3 throttle-position-sensor connector were the ones from which you tested continuity to the base of the throttle body?

The only test I saw you report addressed this question: Is the throttle body already grounded? The answer you reported was no.

The only test I had asked for someone to do would address this other question: Would grounding the throttle body make an electrical difference?

Though I see now, reflecting on it, that if you made your test without unplugging the harness connectors, then you did sort of make my test at the same time ... assuming the ground-ref harness wires are eventually grounded to the body, which at least in my Gen 1 diagram, they are.

-Chap

 

Sorry bout that, read too fast.