New Issues with speedo & idle
#1
08-15-2014, 06:01 PM
New Issues with speedo & idle
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?
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?
#2
08-16-2014, 12:28 AM
May want to start by looking for a sticking cable going to the throttle, (throttle cable, cruise control, TV cable), sticking throttle blades, weak return spring, etc.. Have you tried to force the throttle closed to see if idle returns to normal? Are you using a carb or injection?
#3
08-17-2014, 07:50 AM
It's fuel injected (Holley Stealth Ram). Everything is basically new - new throttle body, new intake, etc.
I went and started the car yesterday, the idle is fine. Whatever it was (or is), it's not doing it right now. I have two thoughts on this:
1) At the same time I got home, I tried rolling up the passenger window (power), and it wouldn't go. I opened the garage, moved some stuff around and pulled the car in. Once I shut the car off but with the key on, I tried the window again and it went right up. I'm starting to suspect I have an electrical issue, specifically a bad ground. I've doing a bunch of reading and I'm not positive I have everything grounded the way it should. I'm going to check in a little bit and see.
2) I was stuck in Dream Cruise traffic, then had a 30 minute drive home. That is the longest stretch I've ever had the car driving. When I popped the hood, it was HOT in there. If the problem wasn't electrical, I'm wondering if it was heat related?
I went and started the car yesterday, the idle is fine. Whatever it was (or is), it's not doing it right now. I have two thoughts on this:
1) At the same time I got home, I tried rolling up the passenger window (power), and it wouldn't go. I opened the garage, moved some stuff around and pulled the car in. Once I shut the car off but with the key on, I tried the window again and it went right up. I'm starting to suspect I have an electrical issue, specifically a bad ground. I've doing a bunch of reading and I'm not positive I have everything grounded the way it should. I'm going to check in a little bit and see.
2) I was stuck in Dream Cruise traffic, then had a 30 minute drive home. That is the longest stretch I've ever had the car driving. When I popped the hood, it was HOT in there. If the problem wasn't electrical, I'm wondering if it was heat related?
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