Help forum brothers.... code P0300H
Thread Starter
Drifting
Joined: Mar 2000
Posts: 1,477
Likes: 105
From: st. louis, MO. USA
Help forum brothers.... code P0300H
Ok guys, here's my story.
My check engine light came on today, got me a little freaked out-- first time thats ever happened. So I pull up the old trusty corvetteforum.com. I do a search and learn to pull the codes and even learned what they mean. I got a P0300H. From my reading on here that means an engine misfire detected, and is a history code. My question is, if its history, why did my check engine light just come on today? Do I need to worry about it now?? Should I have my car checked out?? or should I just reset the codes and clear it . Thanks for your help. I did have a cam put in 9 months ago, a small 221 558 116lsa, but didnt have any issues and it has been tuned. Could that have caused it??
Rob
My check engine light came on today, got me a little freaked out-- first time thats ever happened. So I pull up the old trusty corvetteforum.com. I do a search and learn to pull the codes and even learned what they mean. I got a P0300H. From my reading on here that means an engine misfire detected, and is a history code. My question is, if its history, why did my check engine light just come on today? Do I need to worry about it now?? Should I have my car checked out?? or should I just reset the codes and clear it . Thanks for your help. I did have a cam put in 9 months ago, a small 221 558 116lsa, but didnt have any issues and it has been tuned. Could that have caused it??
Rob
Burning Brakes
Joined: Feb 2003
Posts: 871
Likes: 0
who did your tuning? If the car is running fine, then you probably just need to adjust the test condition with edit for how the PCM triggers a misfire at idle/low rpm. Your cam is relatively small, but if left idling long enough, the PCM probably had enough time to capture enough "misfires" (as the PCM thinks it observed) to trip the 300 code.
Le Mans Master
Joined: Jul 2002
Posts: 7,370
Likes: 8
From: Slave to the evil empire
Cruise-In V Veteran
St. Jude Donor '04
The PCM probalby deteted a short duration misfire condition and thats why you got the history code, if you have a current misfire condition the check engine light will flash.
I'd just reset the code and don't think twice about it or you could just continue to drive it normally and after 3 starts (I think?) it will reset on it's own.
I'd just reset the code and don't think twice about it or you could just continue to drive it normally and after 3 starts (I think?) it will reset on it's own.
Thread Starter
Drifting
Joined: Mar 2000
Posts: 1,477
Likes: 105
From: st. louis, MO. USA
not sure what you mean. Change the test condition?? I dont have LS1 edit or anything. So, basically, are you saying I need someone to adjust my idle--like increase it a bit?? it idles at 750-800 now.
I had it tuned when I was at the Cruise In , by DragonsBreath performance.
I had it tuned when I was at the Cruise In , by DragonsBreath performance.
Burning Brakes
Joined: Feb 2003
Posts: 871
Likes: 0
If you don't have access to edit, then I'd just use the advice above and reset the code. It sounds like you don't get the code often enough to really worry about it.. As long as they're history, they're probably just a result of the cam you're running.. Of course if the engine isn't running right, or you're getting a flashing SES, then definitely look into it..
Thread Starter
Drifting
Joined: Mar 2000
Posts: 1,477
Likes: 105
From: st. louis, MO. USA
Thanks guys for your help. I reset the codes and after starting it a twice yesterday, the check engine light went away. Hopefully it was just a one time thing and doesnt come back.
Rob
Rob
Team Owner
Joined: Jan 2003
Posts: 21,234
Likes: 19
From: Freestate Corvette Club! Elkridge, MD
St. Jude Donor '17
Originally Posted by 1999PewterCorvette
Thanks guys for your help. I reset the codes and after starting it a twice yesterday, the check engine light went away. Hopefully it was just a one time thing and doesnt come back.
Rob
Rob
Drifting
Joined: Jul 2004
Posts: 1,756
Likes: 6
From: Gulf of Mexico Florida West Coast
No problem, High compression engine wth alot of HP. You have a history code because it happens intermittently. Your mods although not radical, simply exceed (by a small margin) the factory tolerances of the computer. Reset and have fun! If possible run higher octane.
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Le Mans Master
Joined: Sep 2000
Posts: 6,976
Likes: 527
From: Clouds Over California
Originally Posted by Jamie Mancuso
No problem, High compression engine wth alot of HP. You have a history code because it happens intermittently. Your mods although not radical, simply exceed (by a small margin) the factory tolerances of the computer. Reset and have fun! If possible run higher octane.
If you hook up a Tech II you should see the same amount of misfires on each cylinder due to the cam. It should be uniform. For example, you would see 7-8 misfires per second on each cylinder. Now if it were an individual cylinder, then you would have something else happening. That code is a standard code for cam swaps. You need to go in and adjust the parameters for misfires with LS1edit. Until then just reset it, you are going to get it occasionally until you tune it out.
Thread Starter
Drifting
Joined: Mar 2000
Posts: 1,477
Likes: 105
From: st. louis, MO. USA
Thanks guys for putting my mind at ease. Ragtop Rob, I still have the stock plugs and wires , and have only 24,000 miles on it-- I know, I need to drive it more. I bought new NGK Tr-55 plugs and magnecor wires, just waiting to put them on when I have my headers installed. Hopefully, the car will run nice and smooth. It seems to be running fine right now. A tech II would be a nice little toy to have. How much do those things run?
Rob
Rob
