Need help with severe skip
Thread Starter
Instructor
Joined: Sep 2008
Posts: 233
Likes: 17
From: Macon GA
Need help with severe skip
Need help chasing a severe misfire. Engine misfires when cold started. Misfire is so bad it shakes the car when under power. Also will pop from time to time. As the car comes up to operating temperature the skip will lessen and eventually go away. It is most noticeable when under power and the engine is luging just a little. This skip is serious like it is only running on 5 or 6 cylinders.
NO Check engine light and NO codes????????????
2000 A4 with 38500 miles
Ported & polished throttle body
Z06 airbox with K&N filter
Z06/LS6 intake manifold
Kooks long tubes with X pipe and Corsa Pace cars
Need help on where to start looking.
NO Check engine light and NO codes????????????
2000 A4 with 38500 miles
Ported & polished throttle body
Z06 airbox with K&N filter
Z06/LS6 intake manifold
Kooks long tubes with X pipe and Corsa Pace cars
Need help on where to start looking.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Most likely a SECONDARY IGNITION ISSUE (Plugs and wires)
When it acts up, if its a misfire, you will see the Check Engine Light (CEL) FLASH when the engine is misfiring.
What shape are your plugs and wires in.
You can remove the wires and read each one with an ohm meter. Should be around 300-700 ohms for a stock OEM wire. If there is a very high reading that wire is bad. if the insulation is bad, they will leak and misfire.
If there old wires and plugs, I recommend that you change them
I recommend GM Performance RED wires and AC Delco Iridium plugs.
Bill
When it acts up, if its a misfire, you will see the Check Engine Light (CEL) FLASH when the engine is misfiring.
What shape are your plugs and wires in.
You can remove the wires and read each one with an ohm meter. Should be around 300-700 ohms for a stock OEM wire. If there is a very high reading that wire is bad. if the insulation is bad, they will leak and misfire.
If there old wires and plugs, I recommend that you change them
I recommend GM Performance RED wires and AC Delco Iridium plugs.
Bill
Thread Starter
Instructor
Joined: Sep 2008
Posts: 233
Likes: 17
From: Macon GA
Plugs and wires were replaced at 31000 miles (38500 currently) with Red GM and AC Delco Iridium plugs. Haven't had any issues until now.
Check engine light does not flash when misfiring.
When cold started it runs a very rough, misfires terribly, and when under power it will occasionally pop from the exhaust. After running 10 minutes or so the misfire goes away and the car runs normal. If I don’t let it warm up for that long and drive off, it misfires and jerks a lot. Again, it normally go away after a few minutes. Just acts up until the engine is completely warm. If I leave it in the parking lot for a few hours, I don’t have any trouble with it unless I am starting it completely cold. It shows no codes and no check engine light.
Check engine light does not flash when misfiring.
When cold started it runs a very rough, misfires terribly, and when under power it will occasionally pop from the exhaust. After running 10 minutes or so the misfire goes away and the car runs normal. If I don’t let it warm up for that long and drive off, it misfires and jerks a lot. Again, it normally go away after a few minutes. Just acts up until the engine is completely warm. If I leave it in the parking lot for a few hours, I don’t have any trouble with it unless I am starting it completely cold. It shows no codes and no check engine light.
Drifting
Joined: Jan 2015
Posts: 1,256
Likes: 157
From: Pennsylvania
Pop from exhaust could mean a lean condition and being the problem lessens as the engine warms up it would leave me to believe you have a vacuum leak possibly intake gaskets or pcv hose. Then when the engine warms the leak lessens and makes it less noticeable
Last edited by v8srfun; Jun 9, 2016 at 06:23 PM. Reason: Auto correct got me again
Thread Starter
Instructor
Joined: Sep 2008
Posts: 233
Likes: 17
From: Macon GA
Spent Saturday chasing the misfire:
Removed and cleaned the MAF and all the air bridge components.
Removed and cleaned the throttle body.
Replaced the K&N air filter with a new d a new paper filter
Installed new AC Delco Iridium spark plugs (old ones looked good, I just wanted to be sure)
Cleaned tested all plug wires (there was a little gunk in coil end of the #5 wire)
Double checked all vacuum lines.
Car started instantly and never missed a beat. I checked it on Sunday and today. Runs perfectly. Thanks Bill Curlee and others for their help/advice. This forum is truly a cool place.
Removed and cleaned the MAF and all the air bridge components.
Removed and cleaned the throttle body.
Replaced the K&N air filter with a new d a new paper filter
Installed new AC Delco Iridium spark plugs (old ones looked good, I just wanted to be sure)
Cleaned tested all plug wires (there was a little gunk in coil end of the #5 wire)
Double checked all vacuum lines.
Car started instantly and never missed a beat. I checked it on Sunday and today. Runs perfectly. Thanks Bill Curlee and others for their help/advice. This forum is truly a cool place.
