zex and msd digital window switch

Reply Subscribe

Thread Tools

Search this Thread

Jul 22, 2006 | 12:42 AM

to-fst-4u

Thread Starter

TECH Regular

iTrader: (35)

Joined: Oct 2005

Posts: 433

Likes: 0

From: Salisbury, NC

zex and msd digital window switch

i just got through searching and i found alot of answers to my questions but i am still confused. i have the zex nitrous system with the msd digital window switch. In Zex's installation instructions, they tell you to connect the white wire to the output voltage lead on the tps. i connected the white wire to the blue wire of the tps at the throttle body like the directions said. now whenever the activation switch is off, my car idles at around 1300 rpms and the throttle position sensor reads 6 percent. when i turn the activation switch on and the window switch comes on, the car idols fine and the tps reads 0 like it should. does anyone know what could be causing this problem? is the voltage from the tps backfeeding into the zex box? any help would be greatly appreciated. thanks.

Jul 22, 2006 | 12:45 AM

to-fst-4u

Thread Starter

TECH Regular

iTrader: (35)

Joined: Oct 2005

Posts: 433

Likes: 0

From: Salisbury, NC

also, the msd instructions say to have the box set on 1 cylinder for the ls1 engine. when it is in the 1 cylinder mode, the rpms on the box do not read right, they only read right when they are in the 4 cylinder mode, i have read that people leave them set on the 4 cylinder mode but i was just wondering what the difference was, if any.

Jul 22, 2006 | 03:00 PM

to-fst-4u

Thread Starter

TECH Regular

iTrader: (35)

Joined: Oct 2005

Posts: 433

Likes: 0

From: Salisbury, NC

to the top. any help is appreciated.

Jul 22, 2006 | 05:30 PM

98redorangeta

12 Second Club

iTrader: (10)

Joined: Sep 2005

Posts: 948

Likes: 0

From: From Ohio now in that state up north

Wire in a relay that is grounded by the window switch that controlles the tps wire on the zex box and that high idel should go away.

Jul 23, 2006 | 10:12 AM

01Z28M6

TECH Resident

Joined: Oct 2005

Posts: 781

Likes: 0

From: Taxme, Ohio

Quote:

Originally Posted by to-fst-4u

is the voltage from the tps backfeeding into the zex box? any help would be greatly appreciated. thanks.

Yes it is and the solution may be a 9.6k resistor in-line from the TPS signal wire to the NMU. You can call ZEXTECH (which is COMP Cams) and ask for Rich. I am having the same problem but my NMU has failed and am awaiting its return so I can see if this problem was with the NMU or that I need to add the resistor. Mustang people have been experiencing the same issue.

Jul 23, 2006 | 10:20 AM

01Z28M6

TECH Resident

Joined: Oct 2005

Posts: 781

Likes: 0

From: Taxme, Ohio

Quote:

Originally Posted by to-fst-4u

JFYI, I was told to NOT use my aftermarket ignition window switch with the ZEX kit but do a direct connection to the chassis ground and let the WOT switch control things. I'm not too happy with this limitation so what I have done is to create a new ground circuit using the Mallory window input wire.

I have the Mallory window switch complete a circuit that activates a 30 amp relay that in turn completes my ground to the ZEX solenoids in the NMU. I have also inserted a simple 1 amp diode in parallel with the window ground and +12v power wire to this relay to catch any current which might find its way back to the NMU. I hope this is some help to you.

I have a Mallory 685 Hyfire and a ZEX 82026 wet kit.

Last edited by 01Z28M6; Jul 23, 2006 at 10:26 AM.