8 replies to this topic

[juliancates]

Recently I had to re-do my kill switch and since the existing switch was installed in the vent panel to the driver's left, I figured it might be easier to pull the dash to see how the previous owner installed everything.

I wound up moving the switch to the main hoop on the passenger side and used DaveW's wiring methodology. I don't think this is causing my problem, but I mention it for the sake of completeness.

The problem itself is that when I start the car now, it is a little hard to start (only a very little. It starts up without effort, but it doesn't start as quickly as it previously did), the idle sounds high to begin with (need to hook the tach back up to quantify), and the idle speed seems to progressively rise.

The only things I've done are the kill switch re-do as mentioned earlier, and the dash was completely out.

I'm sure I forgot to reconnect something... but what would make a previously well-running car behave this way? I thought perhaps I had the throttle cable hung up, but it appears to be free of obstruction and working properly. Any other ideas?

This is a 1991, btw.

Appreciate any thoughts, I'll try to hook the gauges back up and take a video to better describe what's going on.

Cheers,

Julian

[john mueller]

check all grounds... There are several.

[juliancates]

check all grounds... There are several.

Thanks, John, I'll doublecheck everything. What exactly would cause this if not grounded properly? Here's a quick video of what I'm seeing. (I'm not touching the throttle at all in this vid...)

http://vimeo.com/21045075

[Keith Novak]

What exactly would cause this if not grounded properly?

A bad ground.

[juliancates]

A bad ground.

LOL, I guess I put that one up on a tee for you.

Seriously though, I'm trying to understand what specific component (ECU? AFM? etc. etc.) if not properly grounded would trigger a 3000 rpm idle to begin with that would seemingly just keep on increasing. Sorry if it's a remedial question, I'm new to the Miata and am still working to understand how everything works when it ... works. Let alone troubleshoot.

[juliancates]

OK, there were a few things I forgot to plug back in. They were seemingly unimportant things, though, like the map lights on the dashboard. Plugging them in had no effect, but now they're plugged in.

Trouble is, before I pulled the dash out, MOST things were already unplugged, so I'm having a hard time remembering. It seemed so simple at the time. *sigh*

This looks important. The black wire is grounded, although I can't for the life of me recall where it is supposed to go. Anybody recognize it? I show voltage through the voltmeter when using a hot wire and this ground wire. But then, when I probe the metal parts of the dash, it appears I'm getting good ground there too. What the heck am I missing?

[juliancates]

Also, is there perhaps a list of the under-dash ground connections, and physically where they should be connected? If there are many, I imagine it would be worth it to go through a list and check off that they are indeed in place.

[juliancates]

Well, I checked and double checked. I see two grounds under the dash... one on the far right, and one on the far left. The far left ground was unattached, but after making sure it was solidly connected (no paint in the way, etc.) to the body, I still get the same results. I don't see any other ground wires under the dash... should there be?

[juliancates]

Well, it's NOT an electrical problem.

I had ruled the throttle cable out, as it didn't appear to be hung up and looked like it was returning to fully closed. When somebody on another forum suggested it as the likely culprit, I decided to revisit it. I unhooked the throttle cable altogether and started the car... it runs like a champ.

Well, at least I managed to get REAL familiar with the under-dash wiring.

Now to put it all back together and drive the pee-diddly-diddly out of it!