I meant borescope my bad, and for eddy current yea you use one to check how clean some things are not use often tho. And you know a lot more than just cars what the…

 

I was an Inspector too and used NDT for 40 years.

 

WHATTTTTTT DAMNNN bro that’s actually crazy, what’s ur fav method? Fav method and easiest method? Pt,mt,UTT,Eddy current, or RT I swear RT is the bs one with that heavy *** camera

 

Long thread and this may not get seen but I had misfires as well and changed out both O2 sensors (this was a WRX) but the issue wasn’t clogged cats or O2 sensors. It was a mid reading mass airflow sensor. The sensor itself was fine. It was the wire connection that had build up corrosion. Cleaned and perfect.

moral, simple things can sometimes be the answer.

 

I bought a 2015 Stingray M7 about 2 months ago with 42,000km on it. About two weeks ago I had a very similar experience to what you've described.

First on the highway the coolant temp went high, not all the way overheated, but i slowed down and the temp dropped.

A short while later, coming off a red light, what felt like the clutch completely failing - hardly any power, pedal not returning. Came to a stop, proceeded again, car was fine. Strangely, not much smell of a burned clutch.

About 6 hours later I'm cruising along at about 40mph on a backroad and "Service Stabilitrack" comes up on the dashboard with a flashing check engine light.

I pull into a parking lot and as I come to a stop the engine gets extremely rough, then when stopped its like an earthquake at idle.

Towed it home, had P0300 random misfire, and a smattering of other codes related to MAF, MAP and throttle position correlation/sensor levels.

I had an appointment at a shop to have a set of longtubes installed, i told him what was going on and he said bring it in.

He pretty quickly had the plugs out, #3 soaked in oil, rest ok. Hypothesis is when it overheated the rings expandeded and the piston broke, or atleast began to. The next time it cooled then warmed up again it was done for.

Very anxiously waiting the 4-6 weeks it's going to take to get it back with forged pistons and h-rods, a more aggressive cam with dod delete, a twin plate clutch and a dyno tune (plus the longtubes i went there for in the first place).

 

okay so how much did you end up having to spend?

 

$16,228.77 CAD, at today's rate $11,830 USD


Gen V LT1 build with clutch and tune

 

oh gawd, I might be having to pay the same thing I’m scared bro I was only wanting to do maybe 3 grand.

 

also wanted to ask did you hear any ticking did you examine your misfire as in just revving foot slowly going up then looking at rpm’s bouncing weirdly? I’m wondering because on my bank 1 cylinders which is the driver side cylinders they are mainly misfiring but bank 2 is no problem at all, I also feel like the shop straight up up charged the mess out of you man, because my shop tried hitting me with that before even examining my misfire, that’s just throwing parts at it and not a good shop, just saying you could’ve saved bread but for my position i definitely can’t spend no 16k currently right now

 

So the sounds i was hearing was like huffing and puffing from the intake manifold at idle, I made extensive logs of the misfire, but the data was all over the place.

What im pretty sure happened was the #3 piston broke, oil got into the combustion chamber, fouled the plug, oil got out the exhaust port and killed bank 2 o2 sensor 1, it started leaning out one bank and richening the other (trims were extreme at +25/-25), causing misfires all over the place. Oil pressure was high at idle, about 50% higher than usual. No evidence of headgasket failure.

What i observed was hard starts, several seconds of cranking then sputtering before getting to a rough but stable idle - which was now sitting high at about 1000rpm. Revving the engine would put it in limp mode until codes were cleared again, but before that happened, revving would smooth things out almost completely. It also drove fine unless it went into limp mode, but would begin idling very rough when stopped.

This is the bill after quite a bit of conversation, a conversation that had already begun when I came to the shop for the longtube headers install, and I was going to do a z51 throttle body with a modded lt2 intake manifold (I still may do these too).

So far I'm very impressed with the service and knowledge at this shop, they're extremely well reviewed and just by looking at what they have on the go, they're not hurting for my business or an upsell.

Had i wanted to just replace the one piston, and the several other things needed to get it running again, he would have quoted me on that, but realistically if the engine is being removed from the chassis and torn down to the crankshaft, its really not in my best interest to put a new oem piston in, just to have #7 do the same thing down the road. This is also eliminating any chance of lifter failure, and should be an impressive gain in power, with a solid base to build on without worry.

I'm pretty confident that this is my best value option, I haven't priced around at other shops, but even if I did i'd still be second guessing myself on the choice I made.

 

okay that’s understandable, for mines it’s like it idles at 500-600 rpms when I did just a tiny bit of going up to 4k rpms mind you the car would mumble so I’d need to apply more throttle to get it out of doing that to get it to go, after that I had blinking engine light and my car would idle rough but then it’ll fix itself. So I’m hoping I don’t gotta spend that much money but I’ll update you when my shop tells me what’s wrong with it

 

fingers crossed for you man, hopefully its not anything serious!

 

hey man update they’re 2.5 hours into my diagnosis and trying to still find out why it’s misfiring currently they’re hourly is 150/hr and I’m at 450 basically on my diagnosis. Is that normal? Personally I’m thinking like it would be cool if it was 2 hours but 3 now? Then plus I have to pay for repairs aswell.

 

Who is doing the diagnosis ??…a general repair shop or a dealership ??…as I’ve said a million times on this Forum those 2 types of shops do NOT have the diagnostic equipment to quickly and accurately diagnose a misfire…if they haven’t done so they will just start replacing parts…keep us informed !!

 

it’s a shop that works on alot of corvettes. I tried calling a Chevy dealer and they’re foreman mechanic was saying that they don’t work on 2014’s.

 

“Working” on Corvettes doesn’t mean they know how to diagnose them…it’s two different skill sets…and a dealership said they don’t work on 2014 ??…that’s unbelievable !!!

 

yeah and If they are using that scope thing i mean it shouldn’t be so much, but it honestly just feels like this shop is just running up they’re hourly trying to find something to blame the misfire on. And ima end up just paying for a diagnostics that didn’t help me, and having to take it to somewhere else. I’ll try to call other dealerships but I don’t want to keep driving that car since it’s misfiring, it’s not like too too bad of misfires but still I don’t want it to get worse.

 

I highly doubt they are using a scope and the same goes for dealerships….dealerships make money not selling cars but on service…do you thing they are going to use equipment that identifies a problem in an hour ??…no !!…they will start throw parts at it once they can’t find anything !!

 

well my solution to this then I’ll just take the hit on this and try my best to negotiate with the guy. Because he would brag on how “I work on 50 corvettes a day” so I would hope he could back up his word

 

Ask him if he uses an automotive oscilloscope to diagnose misfires…let us know.