engine miss at idle in drive
Thread Starter
5th Gear
Joined: Mar 2023
Posts: 5
Likes: 2
From: North Carolina
engine miss at idle in drive
I have a 96 C4 with 99,400 miles. A new Petris vented Optispark, OEM Opti and water pump drive seals in timing cover, OEM Ignition Coil, Ignition control module and spark plugs, NGK spark plug wires and Gates water pump less than 2,000 miles ago.
I have an engine miss at idle in Drive (Stop light) that is random and varying degrees of severity. Seems to run smooth any other time. 22.2 mpg. No codes. I do not see any arcing on the wires during a miss event, so I have not misted the spark plug wires with a spray bottle. Concerned about cracking a hot spark plug insulator. Any ideas?
I have an engine miss at idle in Drive (Stop light) that is random and varying degrees of severity. Seems to run smooth any other time. 22.2 mpg. No codes. I do not see any arcing on the wires during a miss event, so I have not misted the spark plug wires with a spray bottle. Concerned about cracking a hot spark plug insulator. Any ideas?
Last edited by dal39b; Jul 25, 2023 at 06:19 PM. Reason: Verify correct title information
Melting Slicks
Joined: Jul 2005
Posts: 2,214
Likes: 302
Once you rule out fuel and spark, I'd run a leak down test.
I chased an idle misfire for a while until I did a leak down test and surmised that I had a stuck ring on the #7 piston. As a hail Mary, I put some CD2 oil additive in and after about 50 miles of driving the misfire went away (the piston ring likely got un-stuck).
At higher rpms than idle, the leakage rate was too small of a percentage of the total air intake so the misfire would disappear.
I chased an idle misfire for a while until I did a leak down test and surmised that I had a stuck ring on the #7 piston. As a hail Mary, I put some CD2 oil additive in and after about 50 miles of driving the misfire went away (the piston ring likely got un-stuck).
At higher rpms than idle, the leakage rate was too small of a percentage of the total air intake so the misfire would disappear.
Thread Starter
5th Gear
Joined: Mar 2023
Posts: 5
Likes: 2
From: North Carolina
Once you rule out fuel and spark, I'd run a leak down test.
I chased an idle misfire for a while until I did a leak down test and surmised that I had a stuck ring on the #7 piston. As a hail Mary, I put some CD2 oil additive in and after about 50 miles of driving the misfire went away (the piston ring likely got un-stuck).
At higher rpms than idle, the leakage rate was too small of a percentage of the total air intake so the misfire would disappear.
I chased an idle misfire for a while until I did a leak down test and surmised that I had a stuck ring on the #7 piston. As a hail Mary, I put some CD2 oil additive in and after about 50 miles of driving the misfire went away (the piston ring likely got un-stuck).
At higher rpms than idle, the leakage rate was too small of a percentage of the total air intake so the misfire would disappear.
