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I thought there was a thread about this but damned if I can find it now. My 06 has 87K. Somewhere last year it began a random miss at idle only. I blew it off for a later date. Later date showed up this year when it would start having hard misses while doing 60, then at random speeds.....but not with any regularity. A day could pass with no missing, even at idle. Changed the plugs, coil packs and wires. Immediately after it would show on the computer, random misses from cylinder to cylinder.....no pattern. And it would not throw a code. I drove it home. Next day it misses so hard that it lost power, at one point smelled hot, but gauges read everything was normal. Not sure where to go in trying to diagnose this. My mechanic has had it hooked up numerous times to his computer and the only code it will throw is for a stupid tire sensor. Is this a fuel probrelm? Dirt in tank? Although I don't know how. Pressure sensor? Please share your experience. A long time ago I read a thread about the back side of the fuse panel shorting but I don't remember how that turned out. TYA for assistance.
Your mechanic is going to need more than his scan tool to diagnose this accurately…looks like you’ve changed everything in the secondary ignition system but since these are random misfires you may want to find a shop that uses a scope and have them look at the crankshaft position sensor since that sensor controls spark and fuel injection timing…I’d also be current ramping your coil packs and injectors…I’m not saying that is your problem but finding the right person to diagnose this is…a P0300 can be something like torque tube bushing or anything that may cause a vibration in the Powertrain and there is a Technical Service Bulletin that’s been out for a while concerning this…the crank sensor will see anything that slows down the crankshaft as a misfire…you also want to make sure your battery and charging system are up to snuff…this is the first thing I check when I’m dealing with a car with a misfire…where are you located ??…I may know of a diagnostic tech in your area.
Re-torque your intake manifold bolts. They are found to be loose more often than people realize and then they let unmetered air in. Cost to check and fix this: $0.
Aloha....thank you for the quick response. I am located in Kona, Hawaii.....aka Big Island. Is it possible that the sensor has gone bad? Not sure I understand the part about "ramping up".
The crank sensor may be flaking out and the best (only) way to check this would be to use a labscope…a great majority of dealerships and repair shops don’t use one because it takes some acquired knowledge and skill to use one and most would rather guess and charge you a bunch of money on parts…call some shops in your area and see if they use one…if you caught me 5 years ago when I was visiting the Big Island I could have looked at the car for you…was there end of April 2018 just before Kīlauea blew in early May…that one was pretty gnarly…current ramp is looking at the coil pack current flow (about 4 amps) and it looks good if it looks like the scope capture below…looks like a shark fin and it resembles a ramp…if the coil pack is shorted it would go straight up…video on looking at crank sensor with a scope.
This is great information. I do not mind changing some parts within a price thresh hold as I am actually trying to change some things out, fluids, etc. as I go along and as I can afford them. I purchased the car "back of left book" in December of 2019 with 50K miles. I'm third owner. Being on an island tends to wear out some parts quicker than the mainland. Sad I missed you in '18....but didn't have the car yet. Mauna Loa's eruption in December was spectacular for us.....considering I live 28 miles from the summit.....it just didn't last very long! We tend to look forward to anything Madam Pele brings us.....exciting times. Thanks again for the excellent information.
Yes, living on the “Rock” one has to worry about corrosion…you can try the crank sensor but this is only an educated guess…a shop with a scope should be able to diagnose your concern fairly quickly…good luck and if you buy one make sure it’s an OE sensor not aftermarket !!
So as you can see I move at light speed on this. I had to change mechanic assistance mid stream. I took it to a trusted mechanic and had the camshaft position sensor AND camshaft position sensor replaced. Cleared the codes. Condition continues. I drove it home yesterday, about 20 miles between 45 and 55 mph. Had a couple of misses on the way but nothing ugly. This morning, 12 hours later approximate, that sucker is hard missing like there is no compression, lunges especially under pressure like the fuel flow is totally erratic. This is the pattern I had before. Ran great after tune up, next morning crap. But then after some time.....it decides all is well with the world. The mechanic said that it may need to be reprogrammed like a hard reset on a computer. When it surges it runs like a bat out of hell. Is it possible there is a fuel sensor that is nuts? I read a post a long time ago about the back side of the fuse board that shorts is some vettes. I realize I'm grasping at straws at this point. Any help would be appreciated.
Programmed ??…what needs to be programmed ??…better find yourself a diagnostician and not a mechanic…your ECM doesn’t need to be programmed if this is what your mechanic is saying…even though you changed cam and crank sensors you should have both scoped…tell your mechanic he has to do a crankshaft variation relearn after replacing those sensors…did he ??…without someone with the right diagnostic equipment you will never get this fixed without changing a bunch of parts !!
Thank you for the fast answer. He spent an hour with me yesterday explaining the options......and variation relearn maybe what he meant by reprogram. Again, thank you.
My regrets on not being speedy with the solution that I found. I took to the Corvette Guru on the Island. It took him a couple of days to trace the problem back to the ECM. Got a new one and problem solved. Except now it throws a 430 code.....but the random miss is over. Just dealing with the code. Runs like a bat out of hell!
Don’t know what your Tech found wrong with the ECM but if it cleared the misfire he may have guessed right unless he can specifically tell you what was wrong with it…a P0430 (Cat Efficiency Low) on Bank 2 is ONLY A SYMPTOM…something caused the cat to degrade over time like misfires that have gone unchecked for a while and has been dumping fuel into the cat overheating it as well as possibly clogging it…an exhaust leak anywhere between the O2 sensors can also cause it as well as excessive blow by or coolant getting to the cat…some causes below…will be on Oahu next week for a few days…read you just had a 4.2 magnitude earthquake off Kona…mahalo !!
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
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Random Miss to Hard Miss
