Weird Electrical Problem??

[dwhiskie]

Ok,Had a new 308 put in awhile back and had nothing but problems getting it to run right.Over the last couple months have made progress but still not there.The strange thing is,when I set the tps using green and blk wires,I cant get it to read a steady # but if I ground the blk wire to 1 of the screws that mounts the tps I can get it to set right and as soon as I take that ground wire off it goes back to random #s.I got the ground from -bat to engine and chassi,a ground from back of head to firewall,a the orange wire from wiring harness grounded to a different bolt on drivers side head and the ground from eec to inside chassi under the carpet.Am I missing something here.I just cant figure this out.The last engine (stock) I had ran fine.Any ideas

 

[dwhiskie]

bump

 

[dastang2]

if it is ground you need why not just keep it grounded to that screw and drive it like that. i am not to good with efi but sounds like you got a short somewhere.

 

[dwhiskie]

Because if the signal return "blk wire" isnt right I wonder what else isnt functioning right.I kinda think its running in limp mode and am trying to get some suggestions as to why.I lost as to why

 

[Idwitheld-1`]

You should have +5 vdc from orange to black on the TPS. If you have no ground on the black, the TPS will not work correctly. In fact the green will show +5vdc, this is wide open throttle to the computer and it will enritchen the mix, hence it will NOT run correctly at idle. I would measure out at the EEC to verify you are connected correctly. Most probable is you are disconnected elsewhere. I would not add a separate ground. You want to use the factory supplied ground as this is a REFERENCE voltage. You want to tie into the EEC designeated grounding point on this circuit.

 

[tmoss]

Your ground circuit is compromised somewhere - you need to bite the bullet and find it. It can be a tough task, but check every connector and ground point.

 

[dwhiskie]

How do I find out what wire on the eec is for the tps,and where are all these conector ground points,how do I find them?

 

[jerry beach]

if it is ground you need why not just keep it grounded to that screw and drive it like that. i am not to good with efi but sounds like you got a short somewhere.

I am thinking that you said to test drive the car this way. Thats exactly what I would do. Either that or run a new ground wire to the EEC ground terminal in the car. If it fixes your flutuating TPS voltage then make a permanent solid connection and ditch the old one. I have to agree with what tom said, dont use just any old ground. I dont see how it could make a difference, but he knows his stuff.

 

[tmoss]

How do I find out what wire on the eec is for the tps,and where are all these conector ground points,how do I find them?

I have color wiring diagrams and wiring loom diagrams with ground points at:


www.veryuseful.com/mustang/tech/engine