Man, I'm frustrated. I can't get my system working and have narrowed it down to the RPM switch. I picked up my tach wire under the dash based on a post in the nitrous forum that had good pictures. I was certain I got it because the voltage was changing as I revved the engine. However, the RPM switch is definitely not letting the Zex unit fire. I tried it bypassing the RPM switch and it clicks the solenoids. In addition to trying my wire under the dash, I tried splicing in by the coil packs based on a post by Beer 99C5 on the forum (second wire on the harness on top of the passenger side valve cover), but that made it worse. The engine started misfiring when I armed the unit. I also bypassed the relay setup and wired the RPM switch in directly to the Zex unit to see if I had a bad relay. I am a total novice to the whole nitrous thing, so I don't know if I've overlooked something or my window switch is bad (it was used), or I've not gotten the correct tach wire either try. My window switch is a NOS pill type and I was under the impression that it would work with my car. Am I wrong? Where would I look if I wanted to tie into the tach wire at the PCM? I don't know where to find it. Anyone else running ZEX with a pill type window switch? Thanks in advance!

99 FRC

 

The pcm is in the fender well right front. You just remove tire, then inner well (6 screws) and you'll see it under the battery. You'll see two connectors a red and a blue. You want the red connector, then you want the white wire which is numbered #10, kinda hard to see numbers but if you look closely you'll see it. This is a known good pick up spot. Be carefull these wires are not very heavy gauge. Don't use the blue taps, but rather the red taps that are for smaller gauge wire. Good luck.
Robert

 

Thanks, Robert!

 

not sure if this is gonna help u or not.

but i had some trouble with the same ws. apparently we (ls1's, etc) have to use it in 4 cyl mode.
had the exact same prob with my daughters v6.
i cut the correct wire for 6cyl operation and it would hit and shut off.

ended up cutting the other wires for the 4cyl operation and walla...it works flawlessly

again, fwiw

 

Good point, and true story. They were supposed to have redone the directions to indicate this better, but...
Robert

 

Do you have a drawing of your set up. I thought all ZEX systems wired directly in, with no relay required. If so you can not just wire the window switch to the ZEX box, it will fry your window switch do to the amp draw.
Anyway if you can sketch out the lay out, I would be happy to take a look for you.
Ricky

 

Here's my wiring diagram...



If this link doesn't work, it's the same as on the second page of the wiring section of the nitrous forum, for zex with a window switch.

I think I'm going to just buy a digital switch and see if that helps.

 

Ok first off the window switch is controlling a relay. And that pic is missing alittle data. So with you system armed you should have power at your ZEX box, MSD switch and the 86 pin on the relay.
Yellow wire connected to tach wire and I think set it for 4 cylinders. The msd unit connected to a good ground. At the set rpm the relay should go click allowing the zex unit to read tps now.
IT will only fire if you are at the set point TPS wise.

Put your hand on the relay and see if it is clicking at the proper rpm. if it is then you window switch is fine. IF not take yellow wire attach to ground and see if relay clicks, if it does the window switch or its wireing has issues.

Ricky

 

That's great info! I couldn't figure out how to test all of the components at once when they are all interdependent. I'll try this tomorrow.

Thanks!