I have a 2003 A/E coupe with no mods at all and 23K on the clock, I just recently noticed the engine seems to miss when I am sitting at idle and my wife felt like she was dragging something when she backed up and she looked the car and nothing . I dont know if these 2 things are related or not. The miss in the engine happens intermittenly but it has done every time I have drove the car the last few days. The first thing I did was check the codes and nothing the only code was a U1064H but I dont think that is related to my problem I cleared it and so far nothing has come back. I was going to take to the dealer but I wanted to ask here first. Thank you for your time. My car is an auto.

 

If it was a true misfire you would generate a code (pull a spark plug wire and see). The engine has a "rumble" at idle which is normal. Maybe you wife ran over something and was dragging it around?

 

Best if you could find someone with a scan tool and monitor misfires. You can have slight/inconsistant misfires that might not code till they become more frequent.

Good luck

 

I dont think this is a normal rumble and when my wife felt it she was backing out of the driveway and stopped but nothing underneath, I dont know anyone with a scan tool and the dealer wants $100 just to look at it.

 

Most engine misfires involve the spark plug, plug wire or the coil. Look for loose / not fully seated plug wires. Also look for damaged spark plug wires. When the engine misfires, look at the Check Engine Light (CEL) and see if it FLASHES. If it does, that indicates that the PCM detected a misfire. You have to check for misfire codes WITHOUT turning OFF the ignition switch. Once you turn the ignition off, the code is cleared!

Your rough running engine can also be caused by a vacuum leak OR unmetered air entering the intake manifold.

Check ALL vacuum lines that connect to the intake manifold ESPICIALLY the PCV system lines and fittings. They are exposed to OIL and are well known to rot and crack. Check the entire PCV system from the manifold to the valve cover and look for cracks and rotted rubber fittings.

The air ducting between the Throttle Body and the MAF MUST be air tight! Remove the entire air box/ MAF and air bridge. While you have it out, check the filter and clean the MAF with MAF Cleaner. Also clean the throttle blade and Throttle body.

Reassemble and see if the problem still exists. If you have a bad wire, examining the engine at night or in a dark garage will help identify if you have a high voltage leak caused by a bad wire. The DTC for a random engine misfire is P-0300.

If you need new wires, recommend the GM Performance Red Wires as an upgrade! Excellent wires!

Contact Gene Culley www.gmpartshouse.com $65. for a set

 

Thank You Bill!! I was hoping you would weigh in on my problem , I will do everything you suggest and will post my findings . Thanks again Bill have a great day!!

 

When I had similar symptoms in my C5, it turned out to be a leaky fuel injector.
It was worse just after startup and at idle.
The car "smelled rich" when it was doing this too.
No codes were generated.

Something else to put on your list. Good luck.

Fred

 

I dont smell gas at all but a point well taken.

 

I am going to pull the air bridge and clean everything