with the others. If your plugs and wires are new there's probably a wire that isn't seated properly. Easy to find it a dark garage, you should be able to see it arcing...
P0300 Random/Multiple Misfire
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 939
Likes: 0
From: Clarksville TN
P0300 Random/Multiple Misfire
I took My Z06 to LS Fest Last Month and it ran great. When I got home I parked it in the Garage and let it set for a couple weeks. Last Weekend I got it out and put gas in it. Then I took it to the car wash. While in the Car Wash the "check engine" light started flashing and flashed for about 10 seconds (I think). The Light did not stay on and I did not get any codes. On the way home (maybe 3 miles) the car started missing at low RPM. Still no codes.
This morning I thought I'd drive it to work. This time it was missing so bad it would hardly stay running. The check engine light finally came on and the code was: P0300 Random/Multiple Misfire
The plugs are new and the o2 sensors are new.
The Fuel could have water in it??
The car wash has one of those "undercarriage" cycles that you drive over. And I am wondering if the air filter could have been saturated? (I haven't checked that yet) Has the "Flip Tie" mod, so the filter is exposed......
Any Input?
This morning I thought I'd drive it to work. This time it was missing so bad it would hardly stay running. The check engine light finally came on and the code was: P0300 Random/Multiple Misfire
The plugs are new and the o2 sensors are new.
The Fuel could have water in it??
The car wash has one of those "undercarriage" cycles that you drive over. And I am wondering if the air filter could have been saturated? (I haven't checked that yet) Has the "Flip Tie" mod, so the filter is exposed......
Any Input?
Tech Contributor
Joined: Aug 2008
Posts: 2,902
Likes: 21
From: Oak Hill Virginia
If for some reason you can't find it scan your car for codes with an aftermarket scanner (most auto parts stores will do this for free). The on-board scanner on the C5 will not report the specific cylinder(s) that are missing, it will only show P0300, but an aftermarket scanner will. You will see P0301 for cylinder 1 P0302 for cylinder 2 etc.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
Thread Starter
Burning Brakes
Joined: Sep 2008
Posts: 939
Likes: 0
From: Clarksville TN
Checked it out today. I can't seem to track it down just yet. It's missing so bad the Idle sounds like a HUUUUUGE Lumpy cam.
I'll see if my buddy can bring his scan tool over tomorrow.
I'll see if my buddy can bring his scan tool over tomorrow.
Safety Car
Joined: Nov 2005
Posts: 3,835
Likes: 5
From: Grand Junction Colorado
I have the same thing happening with a 04.Changed plugs,39 k on them.Ck'd plug wire resistence,all around 0.777.Ck'd grounds on passenger head.Ck'd battery.I'm mis firing on 4&6. It ran fine one day and terrible the next?
Le Mans Master
Joined: Apr 2001
Posts: 5,000
Likes: 1
From: Minneapolis, Mn USA
I'd try pulling the intake and replacing your intake gaskets with new Fel-Pro gaskets MS92438.
Check all your plugs for fouling and clean with brake cleaner.
Check/replace your two upstream O2 sensors (left and right side) if they look carboned up. They cannot be cleaned.
Had similar issues with my 04 5.3 Tahoe. Shaky intermittent idle with random miss code and got smoother with higher RPMs. Leaky passenger intake gaskets caused all 4 plugs on that side to be fouled and carboned up the O2 sensor on that side as well. Replacing the intake gaskets and both upstream O2 sensors, and cleaning the plugs took care of all idle and misfire problems.
The GM gaskets were very squished and very flat compared to the sealing plane of the intake manifold. Fel-pro gaskets seem slightly thicker than OEM GM gaskets, which give a little more insurance on making a good seal.
Check all your plugs for fouling and clean with brake cleaner.
Check/replace your two upstream O2 sensors (left and right side) if they look carboned up. They cannot be cleaned.
Had similar issues with my 04 5.3 Tahoe. Shaky intermittent idle with random miss code and got smoother with higher RPMs. Leaky passenger intake gaskets caused all 4 plugs on that side to be fouled and carboned up the O2 sensor on that side as well. Replacing the intake gaskets and both upstream O2 sensors, and cleaning the plugs took care of all idle and misfire problems.
The GM gaskets were very squished and very flat compared to the sealing plane of the intake manifold. Fel-pro gaskets seem slightly thicker than OEM GM gaskets, which give a little more insurance on making a good seal.
Last edited by MN-Brent; Jun 24, 2013 at 12:40 AM.
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
Check for High Voltage leakage or a poor connection on the plug or coil tower.
examine the coil/wires and HV system in a dark area and look for sparks!
You could also have a damaged plug ceramic.
BC
examine the coil/wires and HV system in a dark area and look for sparks!
You could also have a damaged plug ceramic.
BC
