hey i did my na to turbo swap not to long ago... all this time i thought i was hitting fuel cut but i bought a fcd and it got worser.. i was changing my fuses and forgot my guage fuse and now it runs really smoth and gets boost in higher rpm.. big differance.... anybody know whats up with that? do i have to rewire anything? and its a 87 gxl

 

Which emissions harness did you use. The n/a harness or the turbo harness?

 

Never mind. It's obvious from the wiring schematics you used the Turbo Emissions harness. If you look at the connector labled X-15, you'll see that you have the split off Br/R wire from the boost sensor going to the METER fuse.

That can't be good. That means at some period of time you've been feeding 12vdc back towards the output of the boost sensor (the brown/red wire on the boost sensor plug). I've no idea how that would effect a boost sensor or the fcd.

Not only that, you've fed 12vdc to the pin 2B on the ECU. Not good. That pin usually sees less than 4vdc.

You NEED to get a meter out and backprobe pin 2B and go for a drive and see if the voltage rises in boost to approx 3.65vdc or a figure around there. If I remember right a fcd will clamp the voltage at a figure near that as a max figure.

What NEEDS to be done, is you need to go to the X-15 connector and depin the Brown/Red wire in the EMISSIONS part of the harness and to make sure you put heat shrinik over the open pin/socket.

That's a starter anyway. A GOOD series FOUR FSM with wiring diagrams would be the next thing to find and take a gander at.

And to clear something up that I read on this forum that isn't quite right: It's the Boost sensor that feeds the signal to the Boost Gauge, NOT the ECU feeding the signal to the boost gauge. I assume on this paticular car though, the original combination meter for the n./a was kept.

 

I'd also wager that your water temp gauge does not work. Again, it's the X-15 Emissions harness side that carries the water temp signal on a yellow/white wire that then connects to a YB wire on the Front Harness side of the plug. That YB is EMPTY on a non turbo harness. Like it goat nowahrs atall.

On a non turbo car the water temp signal goes to X-16. Soooo you could depin the X-15 and route that wire on the X-15 Emissions side to the proper spot on the X-16 Front Harness part of that plug.

There's a couple of other things that should have gone awry in the X-15. Serious thing? Ehhhh, no really.

 

I also notice that now you have the common ground for the sensors (all those brown/black wires in the Emissions Control System), now also tied to the ground coil for the Alt Warning Light Relay and if you had it, some part of the AVS Control Unit.

For that I would go to the X-15 Emissions Harness and depin the Br/B wire from the plug and treat it like I suggested with the Br/Red wire above.

 

There's one other wire in the X-15. It's Green/Black in color. It's used for the electric fan in front of the radiator. It actually goes to the sensor on the top of the thermostat housing. If you have a electric fan.....I'd guess it's running anytime the key is to ON. IF you have no electric fan......disregard and forget about it.

 

********toke out guage fuse************88888888

The word is TOOK. Toke is something done with mild drug paraphernalia.

TOKE: slang : a puff on a marijuana cigarette or pipe

 

keep pulling out fuses, might get it up to 500RWHP if you pull em all out.

 

Doesent work

 

I pulled the fuses and took the battery out. I don't know about the HP gain, but I'm using a lot less gas now. Thanks for the pointer.

Oh! When I turn the key to Start, nothing happens. I don't even get a click from the starter solenoid. Do you think this is a grounding problem? I understand if I reground everythig in sight, the car will run better.

 

so i simply disconnect the brn/red wire from the boost sensor and it'll all be good? and... running without the fuse will hurt the engine? .. and you must do it to all s4 turbo swaps? never herd of doing this but thanks for your help

 

Nope. Never disconnect the brown/red from the boost sensor. You want to cut the brown/red wire at the plug called X-15. I've posted pictures recently about this on this forum and the other forum.

https://www.rx7club.com/forum/showth...ighlight=meter