2003 Chevy Corvette 2003 Corvette Backfires after starting

STALARIC

MEMBER
2003 CHEVROLET CORVETTE

2003 Chevy Corvette V8 5800 miles

I recently purchased a 2003 Corvette with the 350 LS1 engine. As of this inquiry, I have owned this car for 5 days. The car has a manual transmission, 5800 miles and appears to be in superior condition. I have a 99 day drive train warranty.

When I start the vehicle, after sitting in the garage overnight, it produces 1 to 2 backfire pops. This occurs within the first few seconds or so after starting (2 to 5 seconds). It then seems to be run fine and idles and revs normally after those initial backfires. Two days prior to these episodes, I filled the gas tank with Sunoco Ultra 93 octane.

Any thoughts as to what may be causing the backfires? Any tips for diagnosing the problem?

Thanks much for your feedback and expertise.

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

Common Problems and Solutions

Most causes of backfires in the exhaust system can be addressed by troubleshooting the reason for the air to fuel ratio imbalance. The solution usually involves checking for vacuum leaks, changing the airflow sensor, oxygen sensor, or fuel filter to ensure the fuel system is functioning properly.

A common backfire situation occurs when there is a small leak in the air injection system that feeds the exhaust system. This can cause unburned fuel to explode suddenly. One of the most common causes is a stuck or faulty air intake or gulp valve near the exhaust manifold.

Backfiring can also occur with a sudden drop in fuel pressure. This may be due to a faulty fuel pump or a plugged fuel filter. Correcting problems in the fuel system usually resolves these issues.

Incorrect ignition timing to the spark plugs is another cause of backfire. Adjusting the ignition distributor, if the engine is so equipped, may resolve this problem. Adjusting engine timing is not difficult and can be done with a timing light by following the timing adjustment procedure for your car. If you do not know your car's ignition timing procedure please visit our car repair manual page. A vehicle that is not timed properly will not idle, run or operate correctly and will often backfire rapidly. On newer cars you will need to scan the pcm to check for CKS (crankshaft angle sensor) and CMS (camshaft position sensor) related trouble codes.