Ford Mustang Forums banner

1 - 14 of 14 Posts

·
Registered
Joined
·
12 Posts
Provided you are using a non CAN bus GM harness, you can fish out the tach wire and hook it up like factory to the tach input wire. but using the factory tach is about as accurate as a yardstick measuring a cylinder bore.

Brian
 

·
Registered
Joined
·
9 Posts
Discussion Starter #3
I understand the accuracy of the OEM tach, but I just wanted to know if anyoune got the GM harness/computer will drive the tach.
 

·
Registered
Joined
·
540 Posts
painless will be releasing a gauge converter box in roughly 2 months that taps into the obd2 port and allows one to use aftermarket gauges. I'm planning on getting one since i've already rewired the whole car. also from what i understand, the factory tach output on the GM ecu is set to run in 4cyl mode
 

·
Registered
Joined
·
2,129 Posts

·
Registered
Joined
·
2,995 Posts
all my stock gauges work, except speedo. need new trans shaft for that
 

·
Registered
Joined
·
53 Posts
once i work out all the wiring I expect all my the facotry gauges to work.
Got to figrue out the speedo but I really dont think that's going to be too tuff.
the issue with having something connected to the OBDII port is what do you do when tuning on the street/track, cant use both connections.
 

·
Registered
Joined
·
540 Posts
from what i read about the painless setup is that it splices into the obd2 port. I'm waiting for its release to decide if thats the route i really want to go.
 

·
Registered
Joined
·
7 Posts
As stated above, if you're talking older Mustang's (pre '99), you should have no issue getting every gauge to work just fine, speedo included.

Here's my Fox. TH400 transmission:


My friend's '96 GT with Heads/Cam 6.0L and 4L60E. In the video the tach appears slow, it's just the video for some reason:



And yes, Factory tach's are very innacurate. I was shifting my Fox at 6k, but looks like nearly 7 in the video.
 

·
Registered
Joined
·
815 Posts
As stated above, if you're talking older Mustang's (pre '99), you should have no issue getting every gauge to work just fine, speedo included.

Here's my Fox. TH400 transmission:

'83 Mustang, 5.3L Turbo, 9psi Pump Gas, 0-132 on Drag Radials - YouTube

My friend's '96 GT with Heads/Cam 6.0L and 4L60E. In the video the tach appears slow, it's just the video for some reason:

96 6.0L Mustang Idle tuning - YouTube


And yes, Factory tach's are very innacurate. I was shifting my Fox at 6k, but looks like nearly 7 in the video.
Can you explain how you got each gauge to work? I'd really like to know, I'm going 5.3T/TH400 in my car very soon.
 

·
Registered
Joined
·
7 Posts
It's very simple really. Just use all the stock 5.0L Senders on the LS motor for the water/oil. There is a plug in the RH rear head on the LS motor, remove the plug and drill/tap the head for the Pipe Thread Water sender on the Mustang. Autometer makes an adapter for the oil psi sender threads on the LS motor to take it to pipe thread as well, then just use your 5.0L Oil Sender.

The speedo cable is equally as simple with a cable from these guys:

Speedometer Gear, Speedometer Gears, Ford, GM, Dodge 700R4

It will have a Ford end and a GM end, works great. The Ford and GM speedo heads of that era use the same rev/mile so you then calibrate the speedo by the driven gear just as you would normally.
 

·
Registered
Joined
·
815 Posts
It's very simple really. Just use all the stock 5.0L Senders on the LS motor for the water/oil. There is a plug in the RH rear head on the LS motor, remove the plug and drill/tap the head for the Pipe Thread Water sender on the Mustang. Autometer makes an adapter for the oil psi sender threads on the LS motor to take it to pipe thread as well, then just use your 5.0L Oil Sender.

The speedo cable is equally as simple with a cable from these guys:

Speedometer Gear, Speedometer Gears, Ford, GM, Dodge 700R4

It will have a Ford end and a GM end, works great. The Ford and GM speedo heads of that era use the same rev/mile so you then calibrate the speedo by the driven gear just as you would normally.
Ah that's simple enough.. what about the tach though? I know it'll be off (as it is in your video's), I'd just like it to work.
 

·
Registered
Joined
·
7 Posts
Ah that's simple enough.. what about the tach though? I know it'll be off (as it is in your video's), I'd just like it to work.
Mike i'm sorry about not seeing this post sooner, or responding to your PM. I'm rarely on Corral.net, I sent you a PM with my contact details.

In short, the way you get this to work with the LS computer is use a 'Pull Up' resistor in the tach signal circuit. A quick Yahoo! search will get you what you need.

Also, you need to change the LS computers tach output pulses from 6 to 3 in the tune if using a stock V8 tach.

I'll try to keep an eye on this thread from now on and get to questions a little quicker.

Hey, while i'm here, check out my new project:


lol, Yes, I know I have a sick sense of humor....but how cool is this granny car right! Just got her done recently.

Here's the 1st track video, rushed it together just to make the last race. 7lbs, ultra rich AFR and pump gas. 4150lbs race weight. 15PSI, Race gas times coming Spring 2013:

 
1 - 14 of 14 Posts
Top