Weird MPG bounce and mystery noise

BabyEatingDingo · 06-15-2013, 08:10 PM

I've been lurking around here for a month or so trying to get my car to run. I bought a 1985/2 that was in storage since 2000, non-running. It's an automatic (feel free to hate), but the body is straight and the interior is pretty darn good, with hardly any rust to speak of. Anyway, long story short, the electrical system on this thing was completely messed up; the guy who owned it before me took the approach of "Hotwire ALL the things!" Pretty much every relay, fuse, and the DME, were all blown.

I replaced the DME and virtually every relay and fuse. Today I got the engine to sputter after doing the DME relay bypass thing. The battery died before I could get it to start. I think I need a new one.

I have two weird problems still that I haven't found answers to.

1.) The tachometer isn't bouncing. I put in two new ones (some Spanish off-brand 'FAE' model). The tach still won't bounce, but strangely, the MPG dial under the tach IS bouncing when I crank the engine. What could be causing this?

2.) Whenever the battery is plugged in, there's very strange ticking/knocking sound coming from this box located in front of the battery. I have no idea what this box is, or why it's making this ticking/knocking sound. When I step on the brake pedal, the sound stops, then returns when the pedal is released. What is this thing, and how do I fix it?

mytrplseven · mytrplseven's Garage

That is the Cruise Control actuator. When you press on the brake, it's supposed to disengage the system if it is activated. Sounds like the system is activated all the time and shouldn't be. Looking at the actuator, the cable may be kiinked and it's locking the actuator in the activated position. Pull the cable clip on the actuator and see if the arm it's attached to is free. If it is, pull the Cruise Control fuse (assuming there is one that hasn't been bypassed) and this will likely stop. Why it's actuated may be a relay that's stuck in the activated mode or the cruise control switch on the steering wheel stalk is shorted. When you talk about electrical stuff being miswired, logic goes out the window when trouble-shooting problems.

Can't help you with the MPG bounce.

BabyEatingDingo · 06-24-2013, 11:38 PM

Thanks for the reply. I cleaned a bunch of the wires connected to the cruise control box, put in a new fuse, and cleaned the relay board a bit more. The clicking stopped. Guess it was just some dirty wires?

I haven't been able to solve the tach no-bounce/MPG bounce problem yet. New DME, new tach sensor... anyone have any ideas?