06 corvette.
I get a p0300 pending code.
last year I had the same issue with the pending code but I was able to do set monitors quickly and I think I went straight to smog and it never popped a cel
Smog check is up and I did a drive cycle for about 15 minutes that set a few monitors but still had a few. The next morning I let it idle for a few minutes with a high electrical load and it set the actual cel pretty fast.
so the next morning I cleared them, drove it 45 mins to work, moved the car about 100' at lunch, and drove home. No cel but the pending 0300 was there.
this morning I went to smog and it popped the cel one block from the house.
Tryin to figure what factors contribute to a pending 0300 graduating into an actual 0300 cel.
I wonder if the number of ignition cycles factors in? My current plan is to reset, go do a successful drive cycle and go straight to smog Check.
Any noticeable misfires? It seems that a Corvette's ignition system is very sensitive to the choice of spark plugs and you might get this code if you don't have exactly the right model of spark plugs in:
https://www.corvetteforum.com/forums/c6-tech-performance/3029163-multiple-cylinder-misfire-code-p0300-help.html
it has to see the "pending" cause in some number of consecutive key cycle to set the code. i wish i knew that number.
New plugs and wires and upstream O2's
seafoam/h2o and atf the intake side
run it to set the monitors to ok
Fault codes *should* set in one complete test- which is about 6 miles of driving, 10 min sitting, and then another 3.
Should is the important thing.
It's going to set it with how the car is set up unfortch.
and I can set the monitors no problem.
I just get the pending code after about a minute of idling and it never goes away.
I just want to know what makes it decide that the pending code should become a real code.
the key cycle thing is what I was wondering about
In reply to jfryjfry :
It can set on the next cycle, but.... if I'm reading the post correctly, I assume this car sits a lot? If it does, it needs fresh gas and an injector cleaner run through it too. It's why you don't feel the misfire. Fuel misfires are very soft but spark misfires are hard because you have to light off a double or more fuel load.
The code sets because either or both conditions of a crank reference angle is off or the oxygen sensor is picking up a lean condition from the misfires. That's why I'd put new O2's in to eliminate the sensor being a source of the misfire.
Basically, pending is "I noticed something, let's see if it continues."
CEL code is "It continued long enough that I thought I should warn you."
I'm getting the code because of the cam, and trying to develop the best plan to go through the test with the least likely chance of it moving from pending to real.
that I could drive it 45 mins in heavy traffic and then home after work with no actual code makes me think I can do it.
ac confirmed a suspicion that key cycles might play a role in the process. I just figured someone might know the actual things the ecu needs to see to move it from pending to real.
I'll just drive it until I set the monitors and go straight to the station and not shut it off.
I should have left the motor bone stock... in fact I might just put it all back to oem!
Pretty much every car has different ways of determining pending/CEL, mostly because each set of variables in the vastly different engine configurations all have different operating characteristics. It might be that a P0300 code on a corvette happens after a couple minutes because it uses a 256mhz processor and that's equal to 25,000 processor cycles, and it might happen after the same couple minutes on a Corolla because it uses a 512mhz processor and that's equal to 50,000 cycles.
The drive cycles of every car will be a bit different so they can all conform to EPA OBD2 ranges. I remember on my 96 GM, if I got a CEL and fixed the problem (but didn't clear the code) it took something like 10 or 12 full driving cycles before the code would go away on its own. That's partly just how it worked, and also partly because the longer the light stays on, the more likely you are to open your wallet at a dealer service center.
I can't answer specifically about your LS, but I do know that a rumpity cam can and will trick the knock sensors into thinking there is a misfire. In the LT1s, we got around that by installing LT4 sensors and reflashing with a new set of software parameters. I'm not LS-savvy enough to know if you're getting the P0300 from the crank sensor or the knock sensors, but it should be easy enough to narrow that down. Pull the connectors for the KS and see if the code comes back. Obviously you'll get a knock sensor code, but if the misfire code goes away, you know where to focus your efforts.
Types B and C misfires are determined using a 1,000-revolution window and a two-trip monitor. For a misfire to be identified as type B, it must be serious enough to raise emissions more than 1.5 times the Federal Test Procedure (FTP) standards.
A type C misfire is the least severe of the two and indicates that emission levels are high enough for the vehicle to fail an emission test. In either a type B or type C misfire, the MIL will come on steady and a code will set as long as the condition occurs on two consecutive trips.
