Okay, so I grounded that damn brown and black wire to the Pressure Sensor to fix my 3800 hesitation...well, it made the crap WORSE!!! So I disconnected it. I cannot seem to remember the other fixes...such as...Grounding the EGI Unit. So, which wires do I run extra grounds from...and what other fixes, in a nutshell can fix it? I am determined to fix it tomorrow...

Oh, and you know where the stock air box bolted down against the right side fender? That is where I grounded it to. The suggested fix, grounding to the top of the radiator is impossible being that the little wire coming out of it is no longer there... there is a little nub of frayed wire coming off the radiator...So, dammit Yeah!

 

that little wire coming off the top of the radiator is not a ground wire. I don't know what led you to believe it was. Don't ground that wire.. read the fsm or something.

I hope i read that wrong... anyhow

Double check that pressure sensor wire you grounded too, if you grounded the wrong one, it would have shorted the ecu (thas bad, and i'd be suprised if your car ran at all, let alone like ****).

EDIT: from the archives

EDIT:

And by "top of the radiator" I am 95% sure they mean the upper bumper support, NOT the radiator itself...

 

Okay...Well I couldn't ground it to where it said since mine is not there. However, I grounded the Brown and Black wire to the side of the fender(Inside) where the airbox used to sit. It didn't work.

So, I went with the next step. Checking the 5th and 6th ports...They were not working as they should...I tied the little pushrods down and it sounded better, ran better and didn't stutter. So, I think that I need to pull them off this weekend and clean them. Also, UM...Yeah that's it.

 

Dude... Where did you think it said it was supposed to be grounding? If your car doesn'thave that front bumper support, the car isn't fit to bedriven...

And there are about 30 things that can cause 1 sympton on these cars. Every owner knows chasing them sucks, welcome to the chase. But... "The chase is always better than the catch."

Getting the 5th and 6th ports working will make a big difference. If they were stuck open, your car was losing a ton of low end torque. Fixing this will get your low end back, and keep your high end clean.

 

The LIM gasket is a bitch to clean off the block.
The internal sleeves rarely stick.
Usually it's just the pivot rods.
You will save much trouble if you can pull, clean & lube the aux port actuator rods without pulling the LIM.

To check the general health of the grounds:
With the engine running & the headlights on:
Measure the voltage drop from the alternator frame to the battery (-).
Good grounds will show zero volts.
While you’re there measure the voltage drop from the alternator output post to the battery (+).
That should also show zero.

 

Cool I will check that! Thanks Sure Shot!

Kenteth...The article mentioned a wire coming out of the top of the radiator. There WAS a wire there at one point but it has since been frayed...The bumper supports ARE there! I just grounded it in a different place...and it didn't work! Also, my low end torque isn't suffering at all...It has actually been driving well! I just know that I would rather clean the ports than TIE them open!

 

The wire that comes out of the radiator is a fluid level check. It shouldn't be grounded, it should go to one of the harness packs someplace. I'll try to get some picts of it later today and track down where it goes for you.

Its good you have the bumper support. I'd be scared to drive something that didn't have them. I don't really think that the bumper support would be a 100% excellent ground anyhow, even though it is is metal, its pretty thin. Still conductive though. I'd rather ground to the firewall personaly if its closer.

Tieing the ports open will cause you to lose your low end. If you had an option for driveability if you weren't going to fix them, they are better closed then they are open. You'll get better mpg that way too. Though, they aren't nearly as much fun this way :P

 

I agree...My MPG has gone down since yesterday...hehe...Oh well! It's A LOT more fun!

Thanks, I will keep checking here for that pic and location for the level sensor... Should I try grounding that wire somewhere else?! Do you understand where I grounded it to in the first place?! I suppose I can try another location!

 

The wire appears to go into the wire loom that eventualy leads to the fuel resistor pack. The wire started out as a replacement black lead, which then connected to a brown with white strip wire.

Do not ground that wire... :P (see below for picts)

Which wire are you trying to ground anyhow? The Pressure sensor ground can be grounded wherever convienient (firewall or fenderwell would be good.) Radiator doesn't make for a good ground anyhow, glycol isn't nearly as conductive as metal...

 

Hmm...do I need that little guy?


I was trying to ground the Pressure Sensor...But when I did...it wouldn't rev past 2000 with out almost stalling...I made sure it was the brown and black wire...there were two of them going into the same place...on the connector that is.

 

need... mmm, no.


I'll get back to you tonight of the presure sesnor. Whats the presure sensor code thats printed on the top of it? Like mine is N350...

 

YOU WOULD ASK ME THAT QUESTION RIGHT AS I COME IN FROM THE HOTT HOTT HOTT OUTSIDE WOULDN'T YOU!!!???!!! I dunno...I'll check!

 

Okay...just came back in... N327 6829 E1T12071
Mitsubishi Electric Corp. That is what it says!

 

I think you may be grounding the wrong wire. Remove your ground, and get a DMM. Ground the negative lead from the DMM, stick it on volts, and plug it into each socket on the sensor. You should see the following: one with +12V, one with +5v (for reference), and one that's somewhere between 1-5volts (this is the signal). The one that remains is your ground wire. On a recent '87 base, this wire was completely black. I'd double check with a DMM to make *SURE* that this is the proper wire before grounding it. Good luck.

 

Uh, that's your low coolant sensor.

 

I still can't figure out the hysteria you guys display about grounding every little thing on our cars, lol...But one BIG thing keeps popping into my head about grounding the boost sensor...I don't know about S5's, but on an S4, the boost sensor HAS NO physical local ground, it's grounded through the ECU, and obviously the system is designed this way for a purpose. I don't know why, but I can make an educated guess- the ECU needs to be in control of the ground to assure a "level playing field" for several sensors that determine fuel scheduling (a couple of other sensors are wired the same way, grounded through the ECU)...In other words, let's say the sensors are grounded individually, the boost sensor has a good ground and is sending its 3.5 volts, but the AFM sensor has a shitty ground and is sending a voltage that looks like it's at idle when you're really at cruise, the ECU doesn't know the AFM's got a bad ground, and the voltage input is within tolerances, so the ECU schedules fuel delivery way out of tolerances for the prevailing conditions. With all these sensors sharing the same ground through the ECU, this scenario won't happen...I know this sounds alien to some people, and I probably didn't use an analogy that everyone could understand, but I know you electricians should get it...Moral of the story- you're screwing with your cars important sensors when you try to ground them...

 

So...what's next?! Dammit! you just confused me even more... Should I not be grounding the Boost Sensor...and WHY DOES AN N/A HAVE A BOOST SENSOR!? Or, why is it CALLED BOOST SENSOR?! Hehe...no more yelling at Wayne for me!

 

OK, I'M NOT YELLING EITHER, I just can't seem to get this through you guys' heads- I don't know who started this "ground the boost sensor" thing, but I'm willing to bet he/she don't know jack about electrical systems designs and functions...Listen up, guys- You DO NOT need to add any new grounds to your car (unless you install additional components into an existing circuit, and need to beef up the current-carrying capacity of the circuit)...You need to LOCATE, CLEAN UP, and install correctly (terminal ring contacting bare metal on chassis, instead of a rusty bolt going through a rusty nutplate)your EXISTING grounds...NICE RANT, HUH?

 

Good job! So...I don't need to ground the Computer with EXTRA grounds?! Haha JK!

 

Okay...so check it out. I am sure you have read the first entry...about how I tied the 5th and 6th ports open...it seemed to have solved it...but I have to untie the actuator rods and retie them in order for it to continue working. So, are these actuators operated by a vacuum type system that leaks pressure and eventually allows the ports to close even if the actuator rod is pressed in?

Secondly, I found that I srpung a leak on the secondary injector (Front of motor) where it plugs into the intake manifold. So, today I went to Mazda and picked up two new rings. I am going to install them this weekend. Could THAT be another cause to this issue!?

 

Simple because it's easier than replacing old deteriorated wiring, harness/etc.

 

What could be more simple than removing a bolt, sanding some paint/primer off the chassis metal around the nutplate hole, and reinstalling the cleaned-up terminal/bolt? I realize if the wiring is deteriorated or heat stressed, it's a different story

 

Do you not own a 2nd gen rx-7? Have you ever tried to bend any of the wires on the harness? I think that it's pretty obvious almost everyone of us has a pretty deteriorated (and heat stressed) harness, which is generally the cause of all of our troubles. Most of the time when I have come accross grounding issues, the contact points are immaculate, trace the wiring back and the damn thing is just a wreck. This is why we suggest just adding to, as it most of the time works better than just cleaning up the old contacts, and since 90% of the user base couldn't disconnect the harness properly, let alone rewire it, this is easy.

 

I guess my second gen is in a little better shape than yours, then, I understand what you're saying about the wiring (hell, I'm an electrician), and I handle it as gingerly as I can when I'm pulling engines & such, but ya gotta remember- there are two sides to every circuit, if the whole harness is that shot, replacing half the circuit (grounds) is just putting a band-aid on it...

 

Haha, you must definatly be a newbie to the 2nd gen crowd. Band-aids are about the only thing 2nd gen owners can manage. Generally most of the wiring won't be complete crap, but over age it does deteriorate. But another thing to note is. You're not only *just* grounding the sensor. You're also regrounding the ECU all at once, which helps all around. Obviously you are suggesting the best path, replacing the faulty wiring & cleaning contacts. But with this crowd, and how tight their budgets are. $10 in extra wire as a band-aid is a heck of a lot more appealing than $300+ for a new harness.