I was reading in BlackRx7's post about grounding the how to, only to find out that my pressure sensor has more then 4 wires. The wire that is supposed to be the ground is a brown wire with a black stripe. Suprise! i have 2 brown wires with black stripes and a small square of blue on both wires. I also have a black wire with a white stripe.

What gives?
Evan

 

Are you sure you did a search? These links will more than suffice to your question and the last link was added for good measure. This thread discusses the respective wire that leads to the ECU.

https://www.rx7club.com/showthread.p...ghlight=ground

https://www.rx7club.com/showthread.p...ghlight=ground

https://www.rx7club.com/showthread.p...ghlight=ground

https://www.rx7club.com/showthread.p...ghlight=ground

I followed HAILERS outline prior to going with a LT8 and I had no Issues.

 

Yeah, i searched, i was still unclear as to which wire was the ground.

Thanks for the links!

 

i was unclear because i have found more then 4 wires...

 

i have an 87 n/a and dont have a brown with black stripe so i grounded the black wire and noticed almost no difference on 3800 hesitation. I want to know if anyone knows what happens if you drive with pressure sensor unplugged? i tried it and there was no hesitation at all... whats it do?

 

I understand that the later s4's had a Black wire as It's ground, as opposed to a Brown Wire. I had a Black one on my former 88 GXL. This was ditched In favour of a standalone EMS. I don't know what would happen If you drove with It disconnected but I don't see the relevance of trying It to see It's effects.

*EDIT* It's to detect the onset of the Secondary Fuel Injectors to come on line. This determaines the load of It.

 

The secondarys come on when the engine speed is over 3500 rpm each and every time 3500 rpm is reached IF the boost/pressure sensor is disabled, either by taking the vac hose off the sensor or by pulling its electrical plug.

If the hose and plug are left on, then the secondary injectors will come on when the 3500rpm is reached AND there is enough of a LOAD being sensed by the sensor. In other words you can slowly go to five grand and the secondary injectors will not come on because yo havn't put a LOAD on the engine by SLOWLY going to five grand (five grand is just a figure I picked out of thin air, make it any figure you want over 3500rpm).

The sensor also effects the timing of the engine. If the grounding of the black or brown/black wire did not stop the hesitation you might want to try adding additional grounds to the ground wires at the the ECU plugs. See the archeives on this site and a fellow called RXSTER. Pins 2C, 2R,3A,3G on a series four.

 

another thing is that i noticed a rediculous loss of mpg, driving 20 miles used as much as driving 50 miles normally. I could have just been paranoid from unplugging it but does that make sense?

 

What is your VIN?
Mazda supposedly fixed this after a certain point...
http://fc3spro.com/TECH/FAQ/3800.html



-Ted