Hello all,

Over the last week, I've put about 200 miles on my car, making about...400 or so since I rebuilt everything. The entire interior including gauges, rebuilt 383 stroker with HSR, complete trans rebuild, etc. My car is a 1985 with the ECM/MAP system out of a 1990, and I have a full set of Autometer Cobalt gauges. The transmission is the 700R4.

After driving it so much, including a varying speeds & and getting stuck in the Woodward Dream Cruise traffic, I found two new items to worry about/fix. I don't know where to start for either.

* Every once in awhile, mostly at highway speeds or faster (60 mph or higher), the speedometer will jump up and down about 5 miles an hour even though the speed of the car doesn't change. This only lasts for maybe 3-4 seconds at most, then goes right back to acting correctly. This isn't a big deal, but more of an inconvenience.

* A bigger issue. I drove the car a ton, started and shut it off a ton today at the Dream Cruise. I had absolutely no issues with the idle, it was steady at right around 1,000 RPM. After driving home (about an hour, maybe 20 miles), I put the car in park and noticed that it was idling awfully fast - close to 2,000 RPM. When I put the car back in gear, the idle went back down to around 1,000 but then in park, jumped back to 2,000. I'm more concerned about this as it seems it could be something more serious - not sure what causes an idle to change like that. Is it possibly related to the TV cable?

 

1. Get your speedo cable lubricated. Make sure it didn't get pinched or have any sharp bends since the engine was out.

2. Idle could be a number of things. Vacuum leaks are a good place to start. Did you set the minimum idle air after you first rebuilt the engine? Idle speed may need to be adjusted as the engine break-in progresses. I wouldn't worry about the speed going from 2000 in neutral to 1000 in drive; if you're using the stock torque converter it has a pretty low stall speed and would therefore drag the engine speed down quite a bit if it is idling high.

 

Thanks for the advice.

I thought before - I can't remember why now - that I had a vacuum leak. I wasn't able to find one at that time, I'll look again.

Some more information: On Saturday, I went out and started the car and the idle was fine, back to normal. Whatever it was or caused it went away (at least temporarily).

I think I might have an electrical/ground problem. I didn't associate the idle with it, but at the same time that was going on my passenger window wouldn't roll up. After I pulled the car in the garage, I shut the car off, then turned the key back on and the window rolled up fine. I've had some other intermittent symptoms, too - I'm going to go through and check all the main ground straps and points to make sure they're all good.

 

Oh, also - it's not a factory torque converter. It is a Vigilante 2800 stall.