Pressure Sensor Ground - 3500 Hesitation Fix
08-28-06, 08:34 AM
#1
Pressure Sensor Ground - 3500 Hesitation Fix
86 Sport, emissions removed. Otherwise stock.
So I was trying to fix my hesitation issues by grounding the pressure sensor as prescribed by the TSB.
I'm supposed to ground the brown wire with a black stripe (BrB). Slight problem, I don't have one.
There was 4 wires on the plug. Two of them were black (white stripe and, I think, brown). Didn't really pay much attention to those because I wasn't supposed to.
Other 2...
Brown, white stripe, black rings about every 3/4".
Brown, pink (faded red?) stripe, black rings about every 3/4".
IIRC, the black were on the top of the plug (near the connector hump) and the brown were on the bottom.
Ok, neither of those are Brown with a black stripe as far as I can tell. Am I missing something blatantly obvious?
So I was trying to fix my hesitation issues by grounding the pressure sensor as prescribed by the TSB.
I'm supposed to ground the brown wire with a black stripe (BrB). Slight problem, I don't have one.
There was 4 wires on the plug. Two of them were black (white stripe and, I think, brown). Didn't really pay much attention to those because I wasn't supposed to.
Other 2...
Brown, white stripe, black rings about every 3/4".
Brown, pink (faded red?) stripe, black rings about every 3/4".
IIRC, the black were on the top of the plug (near the connector hump) and the brown were on the bottom.
Ok, neither of those are Brown with a black stripe as far as I can tell. Am I missing something blatantly obvious?
08-28-06, 08:45 AM
#2
HAILERS
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I've a 86 and two 87. ALL have a brown/black wire that is ground.
88 models went to a pure black wire for the gnd wire.
The gnd wire should be on the top row next to the Black/White wire.
Black/White......battery voltage
Brown/Black.....gnd wire
Brown/White.....five volt ref voltage
Brown/Red......output from the sensor to the ECU pin 2B
88 models went to a pure black wire for the gnd wire.
The gnd wire should be on the top row next to the Black/White wire.
Black/White......battery voltage
Brown/Black.....gnd wire
Brown/White.....five volt ref voltage
Brown/Red......output from the sensor to the ECU pin 2B
08-28-06, 08:49 AM
#3
Originally Posted by HAILERS
I've a 86 and two 87. ALL have a brown/black wire that is ground.
88 models went to a pure black wire for the gnd wire.
The gnd wire should be on the top row next to the Black/White wire.
Black/White......battery voltage
Brown/Black.....gnd wire
Brown/White.....five volt ref voltage
Brown/Red......output from the sensor to the ECU pin 2B
88 models went to a pure black wire for the gnd wire.
The gnd wire should be on the top row next to the Black/White wire.
Black/White......battery voltage
Brown/Black.....gnd wire
Brown/White.....five volt ref voltage
Brown/Red......output from the sensor to the ECU pin 2B
Thanks again Hailers.
09-25-06, 07:02 AM
#4
Originally Posted by HAILERS
I've a 86 and two 87. ALL have a brown/black wire that is ground.
88 models went to a pure black wire for the gnd wire.
The gnd wire should be on the top row next to the Black/White wire.
Black/White......battery voltage
Brown/Black.....gnd wire
Brown/White.....five volt ref voltage
Brown/Red......output from the sensor to the ECU pin 2B
88 models went to a pure black wire for the gnd wire.
The gnd wire should be on the top row next to the Black/White wire.
Black/White......battery voltage
Brown/Black.....gnd wire
Brown/White.....five volt ref voltage
Brown/Red......output from the sensor to the ECU pin 2B
09-25-06, 08:14 AM
#5
Engine, Not Motor
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Covered here as well:
http://www.aaroncake.net/rx-7/grounding.htm
I believe that I pulled my wire colours and locations directly from the FSM.
http://www.aaroncake.net/rx-7/grounding.htm
I believe that I pulled my wire colours and locations directly from the FSM.
09-25-06, 08:21 AM
#6
Originally Posted by Aaron Cake
Covered here as well:
http://www.aaroncake.net/rx-7/grounding.htm
I believe that I pulled my wire colours and locations directly from the FSM.
http://www.aaroncake.net/rx-7/grounding.htm
I believe that I pulled my wire colours and locations directly from the FSM.
I have a black wire with a brown stripe (I think, I'll look tonight)... is that the same as a black/brown wire?
Edit: 86 Sport
Last edited by My5ABaby; 09-25-06 at 08:31 AM.
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09-25-06, 08:35 AM
#8
Originally Posted by Aaron Cake
Yes. The first colour is always the primary colour, second colour is the stripe.
If that means, brown with black stripe, I don't have that.
Also, in my last post I meant to say
"I have a black wire with a brown stripe (I think, I'll look tonight)... is that the same as a brown/black wire?" Instead of black/brown
Which, from what you said about colors, is not. Sorry for the confusion.
09-25-06, 08:49 AM
#9
HAILERS
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Originally Posted by My5ABaby
OK, I looked again. 2 are definately black, 2 are definately brown...
For some reason you don't seem to be recognizing the STRIPE on the brown or black wires.
The Black/White is 12vdc
Pure black (BrB on 86-87) is gnd.
Brown/White is five volts ref voltage
Brown/Red is the output to the ECU and Boost gauge.
Virtually all those BrB wires are ALL spliced together in the EM harness and terminate at pin 2C on the ECU where they get grounded evidently THRU the ECU to the gnd terminal on top of the rear rotor housing.
I read the factory service bulletin and it said the extra gnd was added because of a problem with the AFM. Since the gnds are all mechanically spliced together inside the EM harness, they used the easily accessible gnd wire at the boost/pressure sensor. Make sense? Got me. That didn't fix my hesitation on my 87 n/a (now turbo). Eventually I found the gnds at the ECU and soldered an extra gnd to them about six inches up the EM harness from the plug and terminated it at one of the studs that hold the ECU bracket in place. By removing that gnd I can make my hesitation come and go at will. I leave it connected all the time.
That said, this does not work for other people who've tried it. Seems to be a hit and miss thing. The extra gnd at the boost sensor certainly didn't work for me.
IF you have two black wires in the upper corner socket, it would sound to me like the factory already reworked your harness. That fix was only for early 86-87 cars, not later.
09-25-06, 09:03 AM
#10
Originally Posted by HAILERS
The plug should look like the jpg attached. BrB in the upper right hand corner. Pure black on your car probably.
For some reason you don't seem to be recognizing the STRIPE on the brown or black wires.
For some reason you don't seem to be recognizing the STRIPE on the brown or black wires.
Originally Posted by HAILERS
The Black/White is 12vdc
Originally Posted by HAILERS
Pure black (BrB on 86-87) is gnd.
Originally Posted by HAILERS
Brown/White is five volts ref voltage
Originally Posted by HAILERS
Brown/Red is the output to the ECU and Boost gauge.
Originally Posted by HAILERS
IF you have two black wires in the upper corner socket, it would sound to me like the factory already reworked your harness. That fix was only for early 86-87 cars, not later.
I'll check again in a few hours when I'm off work. Maybe I'm just seeing them wrong, which I hope. If so, that'd make things alot easier. But... I don't think I am.
09-25-06, 09:39 AM
#11
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Maybe your '86 is one of the early models that had the little differences like the coolant overflow tank located in a different place, higher center console, etc. It could be possible that the wires are slightly different as well. I have one of the early models so I can check to see what color its wires are if you want..
09-25-06, 09:41 AM
#12
Originally Posted by sonorous7
Maybe your '86 is one of the early models that had the little differences like the coolant overflow tank located in a different place, higher center console, etc. It could be possible that the wires are slightly different as well. I have one of the early models so I can check to see what color its wires are if you want..
09-25-06, 10:10 AM
#14
Originally Posted by sonorous7
Yup, mine is too. I'll try and check those wires after I get home today..
Hailers:
If my car was already fixed by a dealership, there would be an additional wire spliced in near the boost sensor. Correct?
09-25-06, 02:36 PM
#15
I looked at my connector again.
B | B/W
------------------
Br/W | Br/R
So yeah, the wire that's SUPPOSED to be Br/B is just B.
Considering this is an 86... is that indicative of something? Such as, it's already been "fixed". There's not an additional wire spliced in anywhere that I can see.
B | B/W
------------------
Br/W | Br/R
So yeah, the wire that's SUPPOSED to be Br/B is just B.
Considering this is an 86... is that indicative of something? Such as, it's already been "fixed". There's not an additional wire spliced in anywhere that I can see.
09-26-06, 06:03 PM
#16
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sorry I didn't get back to you yesterday.. long day at work. Anyway, for what it's worth, again I have one of the early 86's with the coolant overflow tank on the driver's side and the wires coming from the pressure sensor are as Hailers described:
Originally Posted by HAILERS
Black/White......battery voltage
Brown/Black.....gnd wire
Brown/White.....five volt ref voltage
Brown/Red......output from the sensor to the ECU pin 2B
Brown/Black.....gnd wire
Brown/White.....five volt ref voltage
Brown/Red......output from the sensor to the ECU pin 2B
09-26-06, 09:29 PM
#17
Boost in..Apex seals out.
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You could always take a multimeter, and check the readings on each of the wires :-P
That'd be the easiest way of checking which wire is which..I've learned the hard way, NEVER trust the colors the FSM references too. They change practically mid-year it seems, per state (California models, anyways), and different country (Canadian model..)...
That'd be the easiest way of checking which wire is which..I've learned the hard way, NEVER trust the colors the FSM references too. They change practically mid-year it seems, per state (California models, anyways), and different country (Canadian model..)...
09-27-06, 06:56 AM
#18
Originally Posted by adrock3217
You could always take a multimeter, and check the readings on each of the wires :-P
That'd be the easiest way of checking which wire is which..I've learned the hard way, NEVER trust the colors the FSM references too. They change practically mid-year it seems, per state (California models, anyways), and different country (Canadian model..)...
That'd be the easiest way of checking which wire is which..I've learned the hard way, NEVER trust the colors the FSM references too. They change practically mid-year it seems, per state (California models, anyways), and different country (Canadian model..)...
B: 0
B/W: ~12
Br/W: ~4
Br/R: ~2
So, my B is what's supposed to be Br/B. I'm just not sure why...
09-27-06, 11:01 AM
#19
Regardless of what people here will tell you, mazda changed some of the wiring colors during the years. The only thing in the manuals that can be relied upon is the pinout position on the plug, not the actual wire color.
I used to try this "fix" back in the day and I personally never saw it fix anything. ITs cheap and easy and one of several grounding points you can try. I have found the TPS adjustment has more to do with the hesitation than the pressure sensor in my own experience.
I used to try this "fix" back in the day and I personally never saw it fix anything. ITs cheap and easy and one of several grounding points you can try. I have found the TPS adjustment has more to do with the hesitation than the pressure sensor in my own experience.
09-27-06, 01:08 PM
#20
Originally Posted by RotaryResurrection
Regardless of what people here will tell you, mazda changed some of the wiring colors during the years. The only thing in the manuals that can be relied upon is the pinout position on the plug, not the actual wire color.
04-02-07, 08:55 AM
#23
Back from the dead. I ground the black wire and everything seems good. I remember Kevin telling me when he rebuilt my engine that it appeared that there had been a previous engine swap done. So, I'm guessing that the wiring harness was switched at that time.
I'll take a pic of my awesome (humor
) ground later at some point. I put it on the UIM for now until I can find a bolt that fits the water pump (there's an open threaded hole). I think M8 x 1.0 for reference.
I'll take a pic of my awesome (humor
) ground later at some point. I put it on the UIM for now until I can find a bolt that fits the water pump (there's an open threaded hole). I think M8 x 1.0 for reference.
04-02-07, 09:36 AM
#24
just don't ground the B/W wire like I did by accident (doh!) because I was sloppy and didn't meter the wirse. It blew a fuse that I apparently missed when I checked the fuse box the first time, so I thought I had fried my ECU or something until a couple weeks later i double checked the fuses and fixed it.
04-02-07, 10:16 AM
#25
Originally Posted by arghx
just don't ground the B/W wire like I did by accident (doh!) because I was sloppy and didn't meter the wirse. It blew a fuse that I apparently missed when I checked the fuse box the first time, so I thought I had fried my ECU or something until a couple weeks later i double checked the fuses and fixed it.