Problems with 1985, please help
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From: henderson nevada
Problems with 1985, please help
Just purchased an 85 Corvette, having some problems.
This Corvette has a large stereo\dvd system installed with two amps with over 1500 watts of power.
Cars in Vegas and gets up to over 220 degrees sometimes in 110 degree weather perhaps this is normal and does not overheat.
Main problem is that the volt meter comes on and will go down to 11.5 and then down to 11.2 at the lowest and sometimes stalls and has to be restarted. Usually occurs when you are in stop and go traffic. We changed the alternator from factory to a Delco rebuilt with 228 amps to see if this would solve the problem. The idle rpms would go down to 490 so set the idle up to 700 but it will go down from there after driving will go down to 520 at a stop light. Also the fuel reserve light will come on at times with only 13 gallons gone, also the average mpg is reading 16.7 is this normal? Any suggestions how to fix these problems?
Thank you for your help.
Alan
This Corvette has a large stereo\dvd system installed with two amps with over 1500 watts of power.
Cars in Vegas and gets up to over 220 degrees sometimes in 110 degree weather perhaps this is normal and does not overheat.
Main problem is that the volt meter comes on and will go down to 11.5 and then down to 11.2 at the lowest and sometimes stalls and has to be restarted. Usually occurs when you are in stop and go traffic. We changed the alternator from factory to a Delco rebuilt with 228 amps to see if this would solve the problem. The idle rpms would go down to 490 so set the idle up to 700 but it will go down from there after driving will go down to 520 at a stop light. Also the fuel reserve light will come on at times with only 13 gallons gone, also the average mpg is reading 16.7 is this normal? Any suggestions how to fix these problems?
Thank you for your help.
Alan
Team Owner
Joined: Aug 2000
Posts: 40,156
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From: San Pedro CA
obviously, there is a problem!
I would chase the charging system wiring and make sure the contacts to the alternator and the battery are good.
As for that alternator... damn... if that doesn't cause noise in the electrical system, I don't know what will.
Also, check the Idle Air Control valve, IAC, it's what controls idle.
You must get a factory service manual for that car, too. www.helminc.com or check the parts for sale here, or eBay.
I would chase the charging system wiring and make sure the contacts to the alternator and the battery are good.
As for that alternator... damn... if that doesn't cause noise in the electrical system, I don't know what will.
Also, check the Idle Air Control valve, IAC, it's what controls idle.
You must get a factory service manual for that car, too. www.helminc.com or check the parts for sale here, or eBay.
Last edited by bogus; Aug 26, 2005 at 11:09 PM.
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Joined: Sep 2003
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From: Byfield MA
IAC was the problem in my 85' Vette
I have an 85' Vette that was having stalling problems with an idle speed around 450rpms. It would do just as your Vette does at the stop lights.(Stall) I live in Massachusetts and the outside temp rarely hits the 90's, therefore my Vette operates between 164-185 degrees. Runs great with no problems. My recomendation would be to replace the IAC, Idle Air Control Valve, then completely disconnect the sound system for a while and run the car to see how it responds. Actually I would rather listen to the engine than the sound system. That's what a Corvette's about!!
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Originally Posted by casinomgr
Just purchased an 85 Corvette, having some problems.
Cars in Vegas and gets up to over 220 degrees sometimes in 110 degree weather perhaps this is normal and does not overheat.
Main problem is that the volt meter comes on and will go down to 11.5 and then down to 11.2 at the lowest and sometimes stalls and has to be restarted. Usually occurs when you are in stop and go traffic.
also the average mpg is reading 16.7 is this normal?
Cars in Vegas and gets up to over 220 degrees sometimes in 110 degree weather perhaps this is normal and does not overheat.
Main problem is that the volt meter comes on and will go down to 11.5 and then down to 11.2 at the lowest and sometimes stalls and has to be restarted. Usually occurs when you are in stop and go traffic.
also the average mpg is reading 16.7 is this normal?
Later in the day, I was stuck on I-94 for an hour due to an accident and noticed my volt gauge issue a warning at 11.2. When I put it in N and did a fast idle, the volts bounced back up. No answer for you, but I've seen the same thing.
On my 500 mile road trip I averaged 17mpg in a combination of highway (75 where legal
) and stop-and-go (mostly stopped) for several hours.Sorry I don't have the answers, but it might help to know about similar experiences.
Gary
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Joined: Dec 2002
Posts: 6,715
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From: Santa Teresa New Mexico
Originally Posted by BobLocke1950
I have an 85' Vette that was having stalling problems with an idle speed around 450rpms. It would do just as your Vette does at the stop lights.(Stall) I live in Massachusetts and the outside temp rarely hits the 90's, therefore my Vette operates between 164-185 degrees. Runs great with no problems. My recomendation would be to replace the IAC, Idle Air Control Valve, then completely disconnect the sound system for a while and run the car to see how it responds. Actually I would rather listen to the engine than the sound system. That's what a Corvette's about!!
Le Mans Master
Joined: Dec 2002
Posts: 6,715
Likes: 2
From: Santa Teresa New Mexico
The idle on a 85 has a idle screw on the air intake.
The idle is also controlled by the IAC. On my 85 I sat the idle with the idle screw. You can also replace your IAC.
11.2 volts is a discharge rate, you'll need 12.0+ for a charge rate. A charge takes place at 12.5 and higher.
Unless you like all the power for the tunes chuck it all.
Running temps are normal.
Enjoy the car Dude!
The idle is also controlled by the IAC. On my 85 I sat the idle with the idle screw. You can also replace your IAC.
11.2 volts is a discharge rate, you'll need 12.0+ for a charge rate. A charge takes place at 12.5 and higher.
Unless you like all the power for the tunes chuck it all.
Running temps are normal.
Enjoy the car Dude!
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Joined: Jul 2005
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From: henderson nevada
? on Alternator
Originally Posted by bogus
obviously, there is a problem!
I would chase the charging system wiring and make sure the contacts to the alternator and the battery are good.
As for that alternator... damn... if that doesn't cause noise in the electrical system, I don't know what will.
Also, check the Idle Air Control valve, IAC, it's what controls idle.
You must get a factory service manual for that car, too. www.helminc.com or check the parts for sale here, or eBay.
I would chase the charging system wiring and make sure the contacts to the alternator and the battery are good.
As for that alternator... damn... if that doesn't cause noise in the electrical system, I don't know what will.
Also, check the Idle Air Control valve, IAC, it's what controls idle.
You must get a factory service manual for that car, too. www.helminc.com or check the parts for sale here, or eBay.
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From: henderson nevada
Thanks
Originally Posted by ghlkal
Alan, I too just purchased an 85 - congrats! In driving it home from OH to WI, I was stuck on I-80 moving 4 miles in an hour. I saw temps hit 227 before dropping back down. I don't believe 220* coolant in 110* temp is a problem.
Later in the day, I was stuck on I-94 for an hour due to an accident and noticed my volt gauge issue a warning at 11.2. When I put it in N and did a fast idle, the volts bounced back up. No answer for you, but I've seen the same thing.
On my 500 mile road trip I averaged 17mpg in a combination of highway (75 where legal ) and stop-and-go (mostly stopped) for several hours.
Sorry I don't have the answers, but it might help to know about similar experiences.
Gary
Later in the day, I was stuck on I-94 for an hour due to an accident and noticed my volt gauge issue a warning at 11.2. When I put it in N and did a fast idle, the volts bounced back up. No answer for you, but I've seen the same thing.
On my 500 mile road trip I averaged 17mpg in a combination of highway (75 where legal
) and stop-and-go (mostly stopped) for several hours.Sorry I don't have the answers, but it might help to know about similar experiences.
Gary
Thread Starter
Instructor
Joined: Jul 2005
Posts: 202
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From: henderson nevada
Thx
Originally Posted by BobLocke1950
I have an 85' Vette that was having stalling problems with an idle speed around 450rpms. It would do just as your Vette does at the stop lights.(Stall) I live in Massachusetts and the outside temp rarely hits the 90's, therefore my Vette operates between 164-185 degrees. Runs great with no problems. My recomendation would be to replace the IAC, Idle Air Control Valve, then completely disconnect the sound system for a while and run the car to see how it responds. Actually I would rather listen to the engine than the sound system. That's what a Corvette's about!!
Thread Starter
Instructor
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From: henderson nevada
Set the idle higher
Originally Posted by redwing76
The idle on a 85 has a idle screw on the air intake.
The idle is also controlled by the IAC. On my 85 I sat the idle with the idle screw. You can also replace your IAC.
11.2 volts is a discharge rate, you'll need 12.0+ for a charge rate. A charge takes place at 12.5 and higher.
Unless you like all the power for the tunes chuck it all.
Running temps are normal.
Enjoy the car Dude!
The idle is also controlled by the IAC. On my 85 I sat the idle with the idle screw. You can also replace your IAC.
11.2 volts is a discharge rate, you'll need 12.0+ for a charge rate. A charge takes place at 12.5 and higher.
Unless you like all the power for the tunes chuck it all.
Running temps are normal.
Enjoy the car Dude!
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Instructor
Joined: Jul 2005
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From: henderson nevada
More Power, YES
Originally Posted by AFogleman
You need to get a Capacitor for both of your amps.A 2 Farad would be the best.You are pulling way too many amps on a car that already has charging issues.
