I have an aftermarket GNX style dash with Stewart Warner gauges from the now defunct gnxdash.com/Performance Instruments that Tom Houser used to build.
I talked to Tony from Poston's and they used to get their Dashes from Tom but that is no longer the case. Tom's dashes had an electrical 'something' behind the tachometer which allowed it to be be plugged into the existing harness in the dash. Poston's dashes now have the tachometer plugging into the 2-wires/green pigtail by the alternator.
What happens is this:
Once the car goes between 2K to 3K RPM, the tach drops to 0 (but the scan master is still indicating properly). It will sit at 0 for awhile before 'something' puts it back to where it's supposed to be. I'm having a hard time figuring out if applying pressure to the wiring bundle where the two wires/green plug does anything but it seems like as soon as those new SPALs kick on the tachometer starts indicating properly again.
Note, my tachometer is not wired into the two-wires/green plug behind the alternator, the dash itself plugs into the same harness that the stock harness was plugged into.
Prior to having a bunch of new stuff installed, the tachometer didn't do this at all. It would however park at about 900 or 1K RPM when there is no electrical power applied to the car, but it would drop to 0 with power. I was told that this sounds like there are two grounds crossed together or something that could 'cause this but that just doesn't sound right to me.
I've read that the two wires/green connector can get corroded, and that it can simply be cut off and the two wires soldered together? Is this true?
I'll try to see if it got crimped by the DS header as well...
Any other ideas to help diagnose this will be greatly appreciated...
In addition to the stuff that's in my signature: I just had the following installed in the car:
Blistein Gas Shocks, Eibach Pro-Kit Rate Springs, Energy Suspension Bushings, Gbodyparts Tubular Upper Control Arms, Gbodyparts Tubular Lower Control Arms, Gbodyparts 15” X 10” Grand National Wheels, Spohn Front Upper A-Arm Mounting Hardware Kit, Spohn Lower A-Arm Mounting Hardware Kit, Body Bolts, GNX Bushings, Dual Air bag kit, SSBC Quick Change Aluminum Caliper Upgrade Kit, SSBC OE Replacement Rotors, Cotton’s Upgraded Rear Brakes, Aluminum Brake Drums , Casper’s Headlight Brightener Harness, Casper’s Battery Positive Extender Heavy Duty 102043, Casper’s Negative Battery Cable, Casper’s Fan Harness GN to SPAL Fan, Casper’s Improved Engine Ground Modification Kit, Casper’s Audible Knock Detector, Classictube SS 2-Piece Tank to Pump Line w/Inline Filter Part No# BUF1013, SS Fuel Injection Feed Line Throttle Body Injection Part No# BUC1007, SS Fuel Rail Feed Line Part No# BUF1024, SS Fuel Rail Return Line Part No# BUR1015, SS Completer Brake Line Kit Part No# BU1028, Stop Flex Stainless steel braided Hose kit Part No# SBH6004, SS Emission Tubes (5-Piece) Part No# BUO1013, SS Fuel Lines (3-piece) Part No# BUS1001, SS Transmission Line Kit (4-piece) Part No# BUT1012, SS Vapor Line (1-piece) Part No# BUV1003, Dual 11-inch (2780 cfm) SPAL Pull Fans w/ Shroud, Aluminum Radiator w/Oil & Trans Cooler, 160° Thermostat, High Flow Water Pump, GM Upper & Lower Radiator Hoses, GM Heater Control Valve, GM 3-Piece Heater Hose, GM Bypass Hose, GM Heater Rail Hose, Steel Braided Hose, Pat’s Performance 10” Lock-Up Stall Converter, High Flow Water Pump, Cotton’s Hardened Stator, HR Parts Motor Mounts, 60 lbs/hr High Impedance Fuel Injectors, Turbo Tweak Chip, MSD Ignition Wires, Steve Monroe 62mm Machine Throttle Body & Matching Plenum, Mickey Thompson ET Street Radial Tires P275 / 50R15, Pirelli 235/60R15 P600 Tires, Kirban’s Power Window Motors, Steadfast Column Guard, GM Shifter Handle Assemble, GM Windshield Washer Pump, GM Pedals, Replaced Rear Main Seal, Replaced Oil Pan Gasket, Replaced Front Engine Cover Gaskets, Replaced Transmission Pump & Gasket, and Replaced Engine Oil & Filter.
I know allot of that is mundane and not related but if someone has installed something once that had a synergistic effect on something else then maybe they had the same issue I did and can shed some light.
I talked to Tony from Poston's and they used to get their Dashes from Tom but that is no longer the case. Tom's dashes had an electrical 'something' behind the tachometer which allowed it to be be plugged into the existing harness in the dash. Poston's dashes now have the tachometer plugging into the 2-wires/green pigtail by the alternator.
What happens is this:
Once the car goes between 2K to 3K RPM, the tach drops to 0 (but the scan master is still indicating properly). It will sit at 0 for awhile before 'something' puts it back to where it's supposed to be. I'm having a hard time figuring out if applying pressure to the wiring bundle where the two wires/green plug does anything but it seems like as soon as those new SPALs kick on the tachometer starts indicating properly again.
Note, my tachometer is not wired into the two-wires/green plug behind the alternator, the dash itself plugs into the same harness that the stock harness was plugged into.
Prior to having a bunch of new stuff installed, the tachometer didn't do this at all. It would however park at about 900 or 1K RPM when there is no electrical power applied to the car, but it would drop to 0 with power. I was told that this sounds like there are two grounds crossed together or something that could 'cause this but that just doesn't sound right to me.
I've read that the two wires/green connector can get corroded, and that it can simply be cut off and the two wires soldered together? Is this true?
I'll try to see if it got crimped by the DS header as well...
Any other ideas to help diagnose this will be greatly appreciated...
In addition to the stuff that's in my signature: I just had the following installed in the car:
Blistein Gas Shocks, Eibach Pro-Kit Rate Springs, Energy Suspension Bushings, Gbodyparts Tubular Upper Control Arms, Gbodyparts Tubular Lower Control Arms, Gbodyparts 15” X 10” Grand National Wheels, Spohn Front Upper A-Arm Mounting Hardware Kit, Spohn Lower A-Arm Mounting Hardware Kit, Body Bolts, GNX Bushings, Dual Air bag kit, SSBC Quick Change Aluminum Caliper Upgrade Kit, SSBC OE Replacement Rotors, Cotton’s Upgraded Rear Brakes, Aluminum Brake Drums , Casper’s Headlight Brightener Harness, Casper’s Battery Positive Extender Heavy Duty 102043, Casper’s Negative Battery Cable, Casper’s Fan Harness GN to SPAL Fan, Casper’s Improved Engine Ground Modification Kit, Casper’s Audible Knock Detector, Classictube SS 2-Piece Tank to Pump Line w/Inline Filter Part No# BUF1013, SS Fuel Injection Feed Line Throttle Body Injection Part No# BUC1007, SS Fuel Rail Feed Line Part No# BUF1024, SS Fuel Rail Return Line Part No# BUR1015, SS Completer Brake Line Kit Part No# BU1028, Stop Flex Stainless steel braided Hose kit Part No# SBH6004, SS Emission Tubes (5-Piece) Part No# BUO1013, SS Fuel Lines (3-piece) Part No# BUS1001, SS Transmission Line Kit (4-piece) Part No# BUT1012, SS Vapor Line (1-piece) Part No# BUV1003, Dual 11-inch (2780 cfm) SPAL Pull Fans w/ Shroud, Aluminum Radiator w/Oil & Trans Cooler, 160° Thermostat, High Flow Water Pump, GM Upper & Lower Radiator Hoses, GM Heater Control Valve, GM 3-Piece Heater Hose, GM Bypass Hose, GM Heater Rail Hose, Steel Braided Hose, Pat’s Performance 10” Lock-Up Stall Converter, High Flow Water Pump, Cotton’s Hardened Stator, HR Parts Motor Mounts, 60 lbs/hr High Impedance Fuel Injectors, Turbo Tweak Chip, MSD Ignition Wires, Steve Monroe 62mm Machine Throttle Body & Matching Plenum, Mickey Thompson ET Street Radial Tires P275 / 50R15, Pirelli 235/60R15 P600 Tires, Kirban’s Power Window Motors, Steadfast Column Guard, GM Shifter Handle Assemble, GM Windshield Washer Pump, GM Pedals, Replaced Rear Main Seal, Replaced Oil Pan Gasket, Replaced Front Engine Cover Gaskets, Replaced Transmission Pump & Gasket, and Replaced Engine Oil & Filter.
I know allot of that is mundane and not related but if someone has installed something once that had a synergistic effect on something else then maybe they had the same issue I did and can shed some light.
