Rough idle, shuts off with light throttle.
Thread Starter
Instructor
Joined: Jan 2017
Posts: 136
Likes: 1
From: Orlando Florida
Rough idle, shuts off with light throttle.
Hey guys, I hope I could get some help with doing some pin pointing.
I have a 94 LT1 I just bought, mechanical apprentice trying to do some at home learning.
Started the car(second time since I bought it):
1. I get immediate ROUGH idle.
2. I have new AC Delco Plugs and Wires on there way.
3. Car stays idling rough, barely touch the throttle it dies.
4. Prev owner said car sat for awhile, I put fuel in it. Prev Owner did fuel relay, pump and injectors. There could be bad fuel still in the system?
5. Tested the battery with the car off, held 12 volts and would slowly go 11.9, 10.8. Turned the car on to accessories, 12 volts but the meter acted erratic. 12.0 volts, 8.0 volts, -0L. Tested the meter on an AC outlet to rule out bad meter and the meter is working as intended.
I found out about the wire short trick with the obd port.
The codes I get are C53, H53, H44, H62.
The two times I drove it the car drove on the road fine just had a rough idle, today it won't even let me give it throttle.
First crank it wouldn't fire, second crank was immediate.
Could a bad battery be causing this?
Thanks for the help.
I have a 94 LT1 I just bought, mechanical apprentice trying to do some at home learning.
Started the car(second time since I bought it):
1. I get immediate ROUGH idle.
2. I have new AC Delco Plugs and Wires on there way.
3. Car stays idling rough, barely touch the throttle it dies.
4. Prev owner said car sat for awhile, I put fuel in it. Prev Owner did fuel relay, pump and injectors. There could be bad fuel still in the system?
5. Tested the battery with the car off, held 12 volts and would slowly go 11.9, 10.8. Turned the car on to accessories, 12 volts but the meter acted erratic. 12.0 volts, 8.0 volts, -0L. Tested the meter on an AC outlet to rule out bad meter and the meter is working as intended.
I found out about the wire short trick with the obd port.
The codes I get are C53, H53, H44, H62.
The two times I drove it the car drove on the road fine just had a rough idle, today it won't even let me give it throttle.
First crank it wouldn't fire, second crank was immediate.
Could a bad battery be causing this?
Thanks for the help.
Last edited by Powerstroked89; Jan 20, 2017 at 05:53 PM.
Thread Starter
Instructor
Joined: Jan 2017
Posts: 136
Likes: 1
From: Orlando Florida
I am thinking the battery is the issue, I was planning on taking it to Walmart and having them testing it and grabbing a new battery.
I will try the next two after the battery.
Racer
Joined: Jul 2016
Posts: 320
Likes: 23
Start with the basics, fuel pressure at idle.
When the car is running are you getting at least 13 volts? If so the alternator is fine.
Pull the cat into a garage or outside at night with no lights. Unplug the wire from the coil check the spark (should be nice and white and jump a half inch) from the coil to the wire. If it's good check spark from wires to plug or check the resistance from one end of the wire to the other end.
Report back
Racer
Joined: Jul 2016
Posts: 320
Likes: 23
will do, car won't crank currently(turning the key does nothing), voltage at the battery on run is 1.2 volts. I brought the car home, sat overnight, drove next day. Sat over night and today is when it started, and died on throttle.
I am thinking the battery is the issue, I was planning on taking it to Walmart and having them testing it and grabbing a new battery.
I will try the next two after the battery.
I am thinking the battery is the issue, I was planning on taking it to Walmart and having them testing it and grabbing a new battery.
I will try the next two after the battery.
If you have good voltage when running the battery has nothing to do with your problem.
You can start a car and remove the battery and it will fine just run, until you shut it off and try to restart obviously.
Also when a code reads C that means it's a Current problem when it reads H that means it's stored in the History so those H codes I wouldn't worry about right now
Last edited by Lt4-396; Jan 20, 2017 at 06:45 PM.
Thread Starter
Instructor
Joined: Jan 2017
Posts: 136
Likes: 1
From: Orlando Florida
Start with the basics, fuel pressure at idle.
When the car is running are you getting at least 13 volts? If so the alternator is fine.
Pull the cat into a garage or outside at night with no lights. Unplug the wire from the coil check the spark (should be nice and white and jump a half inch) from the coil to the wire. If it's good check spark from wires to plug or check the resistance from one end of the wire to the other end.
Report back
When the car is running are you getting at least 13 volts? If so the alternator is fine.
Pull the cat into a garage or outside at night with no lights. Unplug the wire from the coil check the spark (should be nice and white and jump a half inch) from the coil to the wire. If it's good check spark from wires to plug or check the resistance from one end of the wire to the other end.
Report back
Measured voltage with car off, and it never held a constant 12v(12, then 11 volts, then 10 volts, then the meter ended up at -0L). On accessories it was the same.
When I went to start the car(before finding it wouldn't even crank) the battery ready 1 volt after.
Should I battery tend it over night, start it in the morning and see if Its hold at least 13v while running? That way I can rule out alternator then I can test fuel pressure(once I pick up the gauge)
I am still very new to all of this so I apologize if I misread your post.
Last edited by Powerstroked89; Jan 20, 2017 at 06:50 PM.
Team Owner
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From: Park City Utah
Thread Starter
Instructor
Joined: Jan 2017
Posts: 136
Likes: 1
From: Orlando Florida
Yeah my thinking is, I drove it and it sat overnight. Next day started right up and drove it and then parked it.
A bad alternator would have shown itself, no? The only thing I did yesterday was replace the switch in the door that shuts off the interior lights when the door is closed.
A bad alternator would have shown itself, no? The only thing I did yesterday was replace the switch in the door that shuts off the interior lights when the door is closed.
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Racer
Joined: Jul 2016
Posts: 320
Likes: 23
Yeah my thinking is, I drove it and it sat overnight. Next day started right up and drove it and then parked it.
A bad alternator would have shown itself, no? The only thing I did yesterday was replace the switch in the door that shuts off the interior lights when the door is closed.
A bad alternator would have shown itself, no? The only thing I did yesterday was replace the switch in the door that shuts off the interior lights when the door is closed.
Do you have a set of jumper cables and another car you can jump it with?
From the readings you got it does sound like a bad battery, you may want to take the terminalsame off and check the battery itself, instead of checking the battery cables just to make sure between the battery and cable are good connections
I had a loose bolt that holds the cable to the battery and the car wouldn't start not even a solenoid click.
It was a bad connection that didn't allow enough amps to pass from the battery to the cables.
When you put the cables back on or on your new battery either use some conductive grease or a very thin layer or dielectric grease.
Thread Starter
Instructor
Joined: Jan 2017
Posts: 136
Likes: 1
From: Orlando Florida
I don't have my jumper cables as I misplaced them in the move. I checked the connections and set my tender on it. Voltage was 12.9 cranked car, it fired and died once it idles for 1-3 seconds.
Gonna grab a new battery in the morning..
Gonna grab a new battery in the morning..
Melting Slicks
Joined: Feb 2003
Posts: 2,677
Likes: 812
From: Saskatoon Sask.
Do you have a set of jumper cables and another car you can jump it with?
From the readings you got it does sound like a bad battery, you may want to take the terminalsame off and check the battery itself, instead of checking the battery cables just to make sure between the battery and cable are good connections
I had a loose bolt that holds the cable to the battery and the car wouldn't start not even a solenoid click.
It was a bad connection that didn't allow enough amps to pass from the battery to the cables.
When you put the cables back on or on your new battery either use some conductive grease or a very thin layer or dielectric grease.
From the readings you got it does sound like a bad battery, you may want to take the terminalsame off and check the battery itself, instead of checking the battery cables just to make sure between the battery and cable are good connections
I had a loose bolt that holds the cable to the battery and the car wouldn't start not even a solenoid click.
It was a bad connection that didn't allow enough amps to pass from the battery to the cables.
When you put the cables back on or on your new battery either use some conductive grease or a very thin layer or dielectric grease.
Racer
Joined: Jul 2016
Posts: 320
Likes: 23
After I reread it I realized how it sounded.
What I meant was use carbon conductive grease or a similar "conductive grease" between the cables and the battery terminal, If that is unavailable use dielectric grease or white lithium grease to coat the outside of the terminals once it is connected to the battery to keep moisture out and protect the connection.
Obviously the best option is the conductive grease
Thread Starter
Instructor
Joined: Jan 2017
Posts: 136
Likes: 1
From: Orlando Florida
So yeah... I am an idiot.
Being in a apprenticeship I work a lot, so my parents offered to take my cash and pick up the car and drop it off at my apartment.
What they didn't tell me was how much gas they didn't put in, just that they did get gas.
So my fault, assumed it was good. Plus the dimmer switch for the dash that brightens or dims it is bad so my screen is very very dim.
Get the battery tested, it tests good.
Then I call and ask, they said "oh we put $5 in it"
So basically barely 2 gallons.
Added new fuel cranked a couple seconds she lives. And I am moron.
However there is some bad news, one of the bolts on the intake manifold had liquid, not much. I wiped it off earlier in the week. And today when I drive it, it's damp again.
A intake manifold gasket and orings aren't too bad on the LT1's are they?
Being in a apprenticeship I work a lot, so my parents offered to take my cash and pick up the car and drop it off at my apartment.
What they didn't tell me was how much gas they didn't put in, just that they did get gas.
So my fault, assumed it was good. Plus the dimmer switch for the dash that brightens or dims it is bad so my screen is very very dim.
Get the battery tested, it tests good.
Then I call and ask, they said "oh we put $5 in it"
So basically barely 2 gallons.Added new fuel cranked a couple seconds she lives. And I am moron.
However there is some bad news, one of the bolts on the intake manifold had liquid, not much. I wiped it off earlier in the week. And today when I drive it, it's damp again.
A intake manifold gasket and orings aren't too bad on the LT1's are they?
Last edited by Powerstroked89; Jan 21, 2017 at 05:57 PM.
Race Director
Joined: Mar 2015
Posts: 15,926
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A air leak will mess you up try snugging them up first. DO NOT disconnect your battery or jump it dead you have enough to deal with with out burning more up.
Dielectric grease is NOT conductive it is more like pipe dope to keep it from leaking.
Dielectric grease is NOT conductive it is more like pipe dope to keep it from leaking.
Last edited by antfarmer2; Jan 21, 2017 at 09:33 PM.
Thread Starter
Instructor
Joined: Jan 2017
Posts: 136
Likes: 1
From: Orlando Florida
Why is jumping going to burn stuff up? Disconnected just fine taking to get it load tested.
Last edited by Powerstroked89; Jan 21, 2017 at 09:52 PM.
Race Director
Joined: Mar 2015
Posts: 15,926
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