Draining and Other Issues
Thread Starter
Racer
Joined: Jan 2013
Posts: 276
Likes: 5
From: Sarasota Florida
Draining and Other Issues
Hey there everyone! It's been a while but i've been working and going to school lately and haven't had time to keep up with the forum. It feel good to be back though!
The car is running pretty good except for a few things i'm hoping some of you could help me out with.
I have a 1987 C4+3 Corvette with the L98 engine. Only 87,700 miles!
Where to start...
It appears that I still have a power drain. Every so often the car will not start and a 2 second jump will get it back on it's feet. Other times it will start up after I let it sit for a few hours from the initial start fail. I took it to a mechanic and he said he's 90% sure it's a 480miliwatt(I think) drain coming from the instrument cluster. He said he does not want to tinker with it because it's an expensive part and recommended me to a local corvette specialist. However, I'm having trouble believing this because when I run the A/C, my voltage drops to 11.3 from the reader on the gauge. THAT'S INSANE! I don't understand how that's even possible. Down here in Florida it's starting to get fairly hot and I can't even use my A/C from fear of the car not starting. I didn't run the A/C for a full month in winter and it didn't die once. Then when summer came around it would die every couple days. How can my mechanic say it's the instrument cluster. I agree it's taking some of the juice but not as much as the A/C. The same goes with the headlights. Huge power drain. Do I have bad relays/fuses? Bad blower motor? The alternator was brand new and battery was brand new when I purchased the car. The instrument cluster is faded and pretty beat up (can't read my MPH) but the repair on one of these is anywhere from 800 to 1200. I'm trying to work my way around repairing it for right now till i'm out of school.
I really need this draining issue fixed. Everytime I drive the car i'm afraid i'll get to my destination and not be able to start it after I shut it off.
I've noticed that the car lacks acceleration when above 1400 RPM. When I punch it anywhere from 1000 to 1400 RPM it screams until i let off the gas. But when I punch it at say 2200 or higher RPM, it's a complete dog. Sometimes, however, it will pick up at those RPMS. Is that a TPS issue? It's almost like the car doesn't know what gear it wants.
Also, I've noticed that my RPM idles fairly low after 30 minutes of driving around. Around 500. Is this also TPS?
My fan only kicks on when the engine reaches 230 degrees. That seems WAY to hot for this engine. Is this normal or is my fan sensor bad?
Aside from other rattles and squeaks from the doors and roof it's flawless.
Any help on these issue is appreciated but the battery drain IS PRIORITY!
The car is running pretty good except for a few things i'm hoping some of you could help me out with.
I have a 1987 C4+3 Corvette with the L98 engine. Only 87,700 miles!
Where to start...
It appears that I still have a power drain. Every so often the car will not start and a 2 second jump will get it back on it's feet. Other times it will start up after I let it sit for a few hours from the initial start fail. I took it to a mechanic and he said he's 90% sure it's a 480miliwatt(I think) drain coming from the instrument cluster. He said he does not want to tinker with it because it's an expensive part and recommended me to a local corvette specialist. However, I'm having trouble believing this because when I run the A/C, my voltage drops to 11.3 from the reader on the gauge. THAT'S INSANE! I don't understand how that's even possible. Down here in Florida it's starting to get fairly hot and I can't even use my A/C from fear of the car not starting. I didn't run the A/C for a full month in winter and it didn't die once. Then when summer came around it would die every couple days. How can my mechanic say it's the instrument cluster. I agree it's taking some of the juice but not as much as the A/C. The same goes with the headlights. Huge power drain. Do I have bad relays/fuses? Bad blower motor? The alternator was brand new and battery was brand new when I purchased the car. The instrument cluster is faded and pretty beat up (can't read my MPH) but the repair on one of these is anywhere from 800 to 1200. I'm trying to work my way around repairing it for right now till i'm out of school.
I really need this draining issue fixed. Everytime I drive the car i'm afraid i'll get to my destination and not be able to start it after I shut it off.
I've noticed that the car lacks acceleration when above 1400 RPM. When I punch it anywhere from 1000 to 1400 RPM it screams until i let off the gas. But when I punch it at say 2200 or higher RPM, it's a complete dog. Sometimes, however, it will pick up at those RPMS. Is that a TPS issue? It's almost like the car doesn't know what gear it wants.
Also, I've noticed that my RPM idles fairly low after 30 minutes of driving around. Around 500. Is this also TPS?
My fan only kicks on when the engine reaches 230 degrees. That seems WAY to hot for this engine. Is this normal or is my fan sensor bad?
Aside from other rattles and squeaks from the doors and roof it's flawless.
Any help on these issue is appreciated but the battery drain IS PRIORITY!
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
The temps are 100% normal.
The "drain" the mechanic is reffering to is from the cluster...miliwatt is minimal...tiny drain from power to the cluster. There are MANY powered circuits on a Corvette that are labeled or described in the book as "hot always". Normal.
IF the drain is enough to kill the battery, have it load tested befor making a judgement, then its a more serious drain. Engine off...it takes a large drain to kill a battery over nite.
If you are seeing under 12V ANYTIME with the engine running....you need one of the following:
new cables to starter and battery
or
clean all the plugs and cables to/from alt to battery and jumper post
or
a new alt voltage regulator/alt and/or a new battery after load testing.
Test both...alt and battery. You should NEVER see 11v with the engine running. NEVER,. thats dirty connections or a tired alt. You SHOULD see 14.5V just after start-up...then 12.5 to 13.5 driving.
Low voltage can cause poor engine performance.
So can low fuel pressure, dirty fuel filter, clogged cats, severly retarded ign timing, and mal-adjusted TPS.
Your car sounds like it NEEDS to visit the Corvette specialist....the avg shop is LOST on Corvettes. The technology may be 30 yrs old to US, but to the average auto repair shop its GREEK..and they bluff their way thru most of the diagnostics, throw a couple parts at the car, since its YOUR money, then tell you its ok to drive. Long enough for you to get it out of their shop.
If you want to do any work yourself you can;t without the FSM set. If your shop had that, it would be fixed...
Everything wrong with your car...has infinite possibilities...could be almost anything with those symptoms...so I';d start with the basics,,, fuel pressure, spark, timing check, TPS set, EGR test and go from there.
The "drain" the mechanic is reffering to is from the cluster...miliwatt is minimal...tiny drain from power to the cluster. There are MANY powered circuits on a Corvette that are labeled or described in the book as "hot always". Normal.
IF the drain is enough to kill the battery, have it load tested befor making a judgement, then its a more serious drain. Engine off...it takes a large drain to kill a battery over nite.
If you are seeing under 12V ANYTIME with the engine running....you need one of the following:
new cables to starter and battery
or
clean all the plugs and cables to/from alt to battery and jumper post
or
a new alt voltage regulator/alt and/or a new battery after load testing.
Test both...alt and battery. You should NEVER see 11v with the engine running. NEVER,. thats dirty connections or a tired alt. You SHOULD see 14.5V just after start-up...then 12.5 to 13.5 driving.
Low voltage can cause poor engine performance.
So can low fuel pressure, dirty fuel filter, clogged cats, severly retarded ign timing, and mal-adjusted TPS.
Your car sounds like it NEEDS to visit the Corvette specialist....the avg shop is LOST on Corvettes. The technology may be 30 yrs old to US, but to the average auto repair shop its GREEK..and they bluff their way thru most of the diagnostics, throw a couple parts at the car, since its YOUR money, then tell you its ok to drive. Long enough for you to get it out of their shop.
If you want to do any work yourself you can;t without the FSM set. If your shop had that, it would be fixed...
Everything wrong with your car...has infinite possibilities...could be almost anything with those symptoms...so I';d start with the basics,,, fuel pressure, spark, timing check, TPS set, EGR test and go from there.
Advanced
Joined: Jan 2012
Posts: 84
Likes: 0
From: Jacksonville NC
I agree on checking all battery/alternator connections and the alternator itself. When I first got my 87 it wouldn't start after sitting a couple of days. The alternator was so tired that one night the battery volts got down to 9 at a stoplight running headlights, heater, and fan. I cleaned all connections and replaced alternator and all those issues went away.
Is the only thing wrong with your cluster is it's hard to read (sun faded)? That can be fixed in an afternoon for less than 60 bucks, check batee.com for replacing the polarization film. Getting the old film off was the most difficult part for me as that old stuff was on there good! Putting new film on wasn't any more difficult than window tint.
Does your car run consistently like that at those RPM ranges? Does engine temp make a difference? What about fuel levels? I had a MAF sensor that would make mine do strange things when it was cold, but hot it would run ok. Currently if mine gets below a quarter of a tank and I punch it, it will take off then act like it was shut off until I let off the gas. Need to check the fuel pump but for now I just keep plenty of fuel in her.
I have a set of the 87 FSM I picked up on here and willing to scan any pages you might want from it to help you out.
Is the only thing wrong with your cluster is it's hard to read (sun faded)? That can be fixed in an afternoon for less than 60 bucks, check batee.com for replacing the polarization film. Getting the old film off was the most difficult part for me as that old stuff was on there good! Putting new film on wasn't any more difficult than window tint.
Does your car run consistently like that at those RPM ranges? Does engine temp make a difference? What about fuel levels? I had a MAF sensor that would make mine do strange things when it was cold, but hot it would run ok. Currently if mine gets below a quarter of a tank and I punch it, it will take off then act like it was shut off until I let off the gas. Need to check the fuel pump but for now I just keep plenty of fuel in her.
I have a set of the 87 FSM I picked up on here and willing to scan any pages you might want from it to help you out.
Thread Starter
Racer
Joined: Jan 2013
Posts: 276
Likes: 5
From: Sarasota Florida
I checked the alternator and battery. Under load at idle in park (with A/C and headlights) the alternator is around 12.9 to 13.1. Under acceleration it skyrockets into the high 13's.
I cleaned every ground wire I could find and even replaced a ground wire head leading to the negative battery cable.
Under acceleration the alternator charges incredibly but at idle it drops to 13.4 on a normal drive with no A/C or headlights. With headlights and A/C on it drops to about 11.1 at idle in drive. To me it sounds like a bad regulator but it's a brand new alternator from the factory. Unless Advance Auto lied to me again, it could just be a refurbished part for all I know.
I do get a random Check Engine Light every now and then after ignition but it's not every time I start the car up.
Timing is correct because a new cap and rotor were installed not to long ago just for a tune-up.
As for the gauge cluster: When I first bought the car I could read the cluster perfectly. No bulbs were out and not much fading. But now (after about 3 months) I can't ready my MPH "bar" and only the farthest right number, the bulb for the oil temp/pressure and miles remaining went out. On top of that everything looks faded compared to other clusters i've seen. I did check out batee.com and for what they do it seems like an amazing deal. I'll get in contact with them soon
The RPM is fairly high on start up. It will idle at 1000 and slowly drop to a solid idle after about a minute. It idles at 600 regularly. When the fan kicks on i see my idle drop to about 500 and fluctuate to 600, and my battery voltage drop to about 12.6. A buddy of mine was trying to find this gremlin battery drain and came up with the idea to increase idle to 700 RPM at all times so the alternator keeps up it's charge and never drops below 12.6. When i'm at a stop light and I see my battery voltage drop, I press the brake and accelerate a tiny bit, enough to get it up to 700/800 RPM, the battery voltage jumps to 13.6 from 12.8. And fuel levels don't really make a difference.
After work on Thursday I will make an appointment at C&S Corvette to see what they can find.
Thanks for the responses! I greatly appreciate it!
EDIT: I was sick this past week and did not drive the car for 4 days. No start and no key in ignition for 4 days. Today the Vette started right up like nothing ever happened. This draining is mind boggling. Even after sitting for 4 days it will not drain. But if I go down the street to the grocery store, it won't start. Lately i've noticed it could be ignition. If the car doesn't start like normal i'll either hold the key down for longer than 5 seconds till it starts or let the car sit for a minute then start it up like normal. Could this be ignition?
I cleaned every ground wire I could find and even replaced a ground wire head leading to the negative battery cable.
Under acceleration the alternator charges incredibly but at idle it drops to 13.4 on a normal drive with no A/C or headlights. With headlights and A/C on it drops to about 11.1 at idle in drive. To me it sounds like a bad regulator but it's a brand new alternator from the factory. Unless Advance Auto lied to me again, it could just be a refurbished part for all I know.
I do get a random Check Engine Light every now and then after ignition but it's not every time I start the car up.
Timing is correct because a new cap and rotor were installed not to long ago just for a tune-up.
As for the gauge cluster: When I first bought the car I could read the cluster perfectly. No bulbs were out and not much fading. But now (after about 3 months) I can't ready my MPH "bar" and only the farthest right number, the bulb for the oil temp/pressure and miles remaining went out. On top of that everything looks faded compared to other clusters i've seen. I did check out batee.com and for what they do it seems like an amazing deal. I'll get in contact with them soon
The RPM is fairly high on start up. It will idle at 1000 and slowly drop to a solid idle after about a minute. It idles at 600 regularly. When the fan kicks on i see my idle drop to about 500 and fluctuate to 600, and my battery voltage drop to about 12.6. A buddy of mine was trying to find this gremlin battery drain and came up with the idea to increase idle to 700 RPM at all times so the alternator keeps up it's charge and never drops below 12.6. When i'm at a stop light and I see my battery voltage drop, I press the brake and accelerate a tiny bit, enough to get it up to 700/800 RPM, the battery voltage jumps to 13.6 from 12.8. And fuel levels don't really make a difference.
After work on Thursday I will make an appointment at C&S Corvette to see what they can find.
Thanks for the responses! I greatly appreciate it!
EDIT: I was sick this past week and did not drive the car for 4 days. No start and no key in ignition for 4 days. Today the Vette started right up like nothing ever happened. This draining is mind boggling. Even after sitting for 4 days it will not drain. But if I go down the street to the grocery store, it won't start. Lately i've noticed it could be ignition. If the car doesn't start like normal i'll either hold the key down for longer than 5 seconds till it starts or let the car sit for a minute then start it up like normal. Could this be ignition?
Last edited by Stephenms; May 26, 2013 at 01:44 AM.
