Street Rat

Did the Seafoam top end cleaner. Soaked for about fifteen minutes. Drove it aggressively as the instructions stated. Nothing in the way of any smoke came out. Back to the house and it's got the miss still.

Popped the hood in the dark garage and ran it. No light shows at all.

C5 Diag

EWMA is "Exponentially Weighted Moving Average"...not something on my scan tool but I think it's basically an average of your misfires over time...the number can go up or down over time...so Seafoam didn't work ??...I'm not familiar with your Actron scan tool but do those misfires increase at idle or under load ??...it looks like maybe cylinder 5 and 6 are the culprits...do the EWMA numbers increase at idle or under load ??….you said the plugs and wire were changed...usually coil packs are pretty bulletproof...you can recheck those plugs and make sure not might not have been cracked during installation....pretty easy to do...are the plug wires FIRMLY seated...I've seen some that were not....injectors were cleaned and tested I hope so we can rule that out...maybe check that you have system voltage at all the injector feed wires...they are the wires that are all the same color ...long term fuel trims are good now ??….if you can't verify which cylinder or cylinders are misfiring maybe do a compression test to rule out anything mechanical !!...I know it's frustrating but without diagnostic equipment this is just hit and miss !!

Street Rat

Rob I appreciate you sticking with me.

More info later today.

C5 Diag

Street Rat

Today's task involved pulling the plugs for inspection. All plugs looked good although I noted oil on the threads of # 2 and # 7. Put anti seize on the threads and a liberal coating of dielectric grease inside the plug boots. About half way through I realized that I should have been testing compression on each cylinder. Major brain fart.
So everything looked good. Took it out for a test drive to see if it would trip a code. No codes. The gremlin is still there.

Going to decipher live data from the scan tool now.

Street Rat

I got this EVA red flashing light at the top of the scan tool. But no codes.

I guess it is the EVAporative system?

Street Rat

I'm beginning to think this is a mechanical issue. I do have some slight valve train noise. I'm progressing to doing a compression check next to see if there is an issue there.

Do these LS3 engines experience valve train issues?

Street Rat

Sorry I haven't checked in for a while. These holidays really take up your time. I have yet to run the compression test on the car. The car runs it just has the blip at idle.
After all of the code and injector stuff I kind of got burned out. Give me a few days and I'll have some answers. I hope.

Street Rat

I have decided to throw in the towel on this job.
I think the next step is to pull the valve covers and take a look. I'm not ready to tear into it quite yet. The car is a daily driver and I need it. I never did the compression test. I'm going to drive it for a while and see if the symptoms increase.

Thanks for all of the input.

Craig

C5 Diag

Craig, Don't give up !!....if you don't want to do a compression test try a "cranking compression test" for the time being... maybe rule out a mechanical issue...put the gas pedal to the floor (clear flood crank) and crank over the engine over...listen if the engine cranks over evenly and consistently...you've been around a while....I know you know what it's supposed to sound like !!

Street Rat

Thanks for the advice.

I'll get it done. Just not now. I'm in a bad place with this car. It's actually my wife's car. She drives a company vehicle. So I'm left this car that I didn't pick out to do daily errands in. The color is red. I'm definitely not incognito. I'd rather not stick out in a crowd. So I'm told that I can't modify the car. The wife says that. Yeah so I'm like tired of HER car!

So I had to rant.

Odo

From my experience and the recount of many members on this forum, some LS3s are known for having a tiny 'lope' when idling. If it's not throwing codes or causing any type of performance loss I'd imagine you're fine leaving it unless it were to progress.

(If I understand correctly, you're saying cleaning the injectors solved the performance issues and now you're just trying to fix the 'blip' during idle? I think you should take a video so we can listen/see what you're dealing with.)

Street Rat

I think that's a great idea. My wife got a new camera for Christmas.

Street Rat

Ok I'm back with the video of this '08 You can hear the miss better at the tailpipe in the video. Do you think the valve train is noisy? I know the injectors are making noise as well. I'm on my phone. Going to get laptop to upload video.

Well that didn't work.
Send me a pm with your email and I'll send it to interested parties.

Street Rat

I have a video created of the offending LS3 engine.
I shot the valve train first with the badged covers off. I proceeded to the rear of the vehicle and recorded the exhaust noise at the tailpipes.

If anyone thinks they can help diagnose this issue, send a PM (Private Message) to me. I will need your email in order to send the video to you.
I sent a copy out the other day. That person thought that I should check in to getting a retune. It's been about six to seven years since I had my initial tune. So that seems to a logical solution.

What say you brothers?

Street Rat

'08 Corvette LS3 misfire

Street Rat

My Movie 20190125_150048 is the name of it if you do a search.

I know. I'm real creative with this stuff.



Forget that name. I changed it. I think.


SEE VIDEO IN ABOVE POST PLEASE