Chugging when accellerating
Thread Starter
Instructor
Joined: Aug 2013
Posts: 159
Likes: 0
From: Wisconsin
Chugging when accellerating
I recently bought a 1985 auto vette for a steal of 1500. Interior needed redoing completely, and it doesn't run the best. I'm trying to figure out what it needs to make it run better.
The car starts up just fine, but if you don't let it warm up for a good 5 minutes it wants to die when you put it in gear. When driving, when you step on the gas it kind of chugs for a second before it starts revving smoothly, especially when you give it more than half throttle. Does anyone know why this is? I bought some sea foam and i'm gonna see if that helps any, but does anyone have any suggestions on what this is and how to fix it?
The car starts up just fine, but if you don't let it warm up for a good 5 minutes it wants to die when you put it in gear. When driving, when you step on the gas it kind of chugs for a second before it starts revving smoothly, especially when you give it more than half throttle. Does anyone know why this is? I bought some sea foam and i'm gonna see if that helps any, but does anyone have any suggestions on what this is and how to fix it?
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
Any Corvette that starts and runs for $1,500 is a good deal.
Start with the basics, plugs, wires, distributor cap. From the old plugs, assuming they're old and recently replaced, you may get a good idea what's happening in the cylinder. Look for signs of rich or lean, oil build up, or coolant.
Check for vacuum leaks, brittle hoses, failing check valves, PCV issues.
Then check fuel, fuel pressure, fuel filter, fuel regulator, fuel pump.
While there are many things that can cause these issues, always start with the basics. By the time you go through these, you will a much clearer picture of what you're dealing with.
Start with the basics, plugs, wires, distributor cap. From the old plugs, assuming they're old and recently replaced, you may get a good idea what's happening in the cylinder. Look for signs of rich or lean, oil build up, or coolant.
Check for vacuum leaks, brittle hoses, failing check valves, PCV issues.
Then check fuel, fuel pressure, fuel filter, fuel regulator, fuel pump.
While there are many things that can cause these issues, always start with the basics. By the time you go through these, you will a much clearer picture of what you're dealing with.
Melting Slicks
Joined: Mar 2016
Posts: 2,778
Likes: 580
From: Langley BC
I think the suggestions given above are very good. I'd definitely suggest you change the fuel filter and spark plugs. Check the condition of the distributor cap and rotor as well as the spark plug wires and replace if necessary. might want to also check the EGR valve and make sure the throttle body is not too dirty... any other issues aside from wanting to die? does it idle at the correct speed? is the check engine light on etc...
Last edited by DMITTZ; Apr 12, 2016 at 04:07 PM.
Team Owner
Joined: Sep 2003
Posts: 20,179
Likes: 673
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
ANYONE buying a used C4 should instinctively replace the fuel filter, first thing.
Needs to be a sticky....
Then you can start troubleshooting from there.
Melting Slicks
Joined: Jan 2001
Posts: 2,940
Likes: 5
From: Chesapeake VA
Incorrect timing could be an issue.
When checking the timing, check the condition of the harmonic balancer. When they get old the outer ring can slip and cause the timing mark to move, thus making the "correct" setting no longer correct.
When checking the timing, check the condition of the harmonic balancer. When they get old the outer ring can slip and cause the timing mark to move, thus making the "correct" setting no longer correct.
Intermediate
Joined: Mar 2016
Posts: 29
Likes: 3
From: Jacksonville FL
I bought an 86' C4 from my father in law a few weeks ago that had been sitting for close to a year. It had similar issues with wanting to die at idle and chugging on acceleration. I drove it to my house which is about 15 miles away and about 4 miles into the trip it start to chug pretty bad and I was losing power and thankfully it stopped and I was able to get it home. I started it up the next day and I had a service engine light. I checked the code which turns out to be my Electronic Spark Control module. I haven't changed it out as of yet but I am assuming this is my problem.
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
I bought an 86' C4 from my father in law a few weeks ago that had been sitting for close to a year. It had similar issues with wanting to die at idle and chugging on acceleration. I drove it to my house which is about 15 miles away and about 4 miles into the trip it start to chug pretty bad and I was losing power and thankfully it stopped and I was able to get it home. I started it up the next day and I had a service engine light. I checked the code which turns out to be my Electronic Spark Control module. I haven't changed it out as of yet but I am assuming this is my problem.
might have a mouse. And old gas.
Last edited by antfarmer2; Apr 13, 2016 at 02:00 PM.
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Drifting
Joined: Dec 2012
Posts: 1,504
Likes: 73
From: Georgetown TX
I recently bought a 1985 auto vette for a steal of 1500. Interior needed redoing completely, and it doesn't run the best. I'm trying to figure out what it needs to make it run better.
The car starts up just fine, but if you don't let it warm up for a good 5 minutes it wants to die when you put it in gear. When driving, when you step on the gas it kind of chugs for a second before it starts revving smoothly, especially when you give it more than half throttle. Does anyone know why this is? I bought some sea foam and i'm gonna see if that helps any, but does anyone have any suggestions on what this is and how to fix it?
The car starts up just fine, but if you don't let it warm up for a good 5 minutes it wants to die when you put it in gear. When driving, when you step on the gas it kind of chugs for a second before it starts revving smoothly, especially when you give it more than half throttle. Does anyone know why this is? I bought some sea foam and i'm gonna see if that helps any, but does anyone have any suggestions on what this is and how to fix it?
Any codes?
Drifting
Joined: Dec 2012
Posts: 1,504
Likes: 73
From: Georgetown TX