Thanks for looking at this... I have looked at various posts on here and have tried to figure out what my problem is.. I have a 92 RS that I swapped out the 305 TBI for a 350 carb and ever since then I have had issues with the gauges acting funky... they will work for a few mins and then start bouncing around and settle back down.. also will do that when I hit a bump.. I have read that it can be a ground issue and I have cleaned the 1 ground point under the dash for the speedo grounds ( made sure the area was down to shiny metal there to ensure a good ground) I've had the entire dash apart and traced all the wiring and done continuity checks on the ground wires for the speedo and they check out good..
The Security light does come on at random also when the gauges are acting up.... The distributor was bought new aftermarket. I've read that the ign module sometimes goes bad and that will cause the Tach to bounce around also. The bouncing around is more so the speedo and the tach, and the other gauges will go to the low side or sometimes be intermittent but not bounce around as badly as the speedo and tach do...
My question here is am I missing a ground somewhere or what? I know there is a group of grounds that are attached to the back of the pass side cylinder head.. I have re-grounded those wires as I am using aluminum heads now. I know that there is a ground on the tach side of the gauge wiring as well.. havent yet messed with it... The connection point on the back of the cluster looks good and seems not to be cracked or broken on the circuit board.. I have cleaned the flex connector as well...
Im sure that this has probably been dealt with before several times and I hate having to ask again but I feel that I have done all I can think of and am just wondering if I am missing something here... I tend to think that the ign module is good because the car drives good otherwise..I've not yet removed the ECM from the equation yet as it is still in place and working..
Thanks again for the input and if I have forgotten anything I will post it up.. Any and all help will be greatly appreciated

 

Aluminum doesn't matter, aluminum is a great conductor. Your electric choke grounds on your aluminum intake, all your previous TBI junk grounded on the aluminum intake as well.

Might as well remove the ECM - it is NOT working! It doesn't do anything unless it gets input from the TBI sensors and the computer-controlled distributor. So, it's dead weight now and not doing anything at all.

But I have no good info to tell you. On my 1992 car that is now carbed, I have no gauge issues at all. Might just be a cluster gone bad. But sounds to me like it's not getting good contacts at the ribbon connector - that always looked like a weak way to connect to me. IIRC, you could maybe shove a folded matchbook cover under the ribbon, making it sit higher and maybe get a better contact with the dash connectors.

 

Thanks.. I'll give that matchbook cover thing a try and see what happens..

 

Was finally able to get time to work on the car and fixed the problem.. I did go ahead and do the matchbox trick and also found the 2 ground wires that grounded to the back of the head were just hanging there, so I got another bolt and lock washer and tightened them back up and took it out for a spin and its not given me any more problems... thanks again camaronewbie for the input there... the computer is now on the hit list to be removed from it