C6 misfire/ECU/diagnostic specialist?

[Godzilla]

My 2005 LS2 C6 convertible suddenly picked up a misfire due to massive overfuelling, but isn't throwing any codes or check engine lights.
Any suggestions as to the cause and who could sort it?
Conventional diagnostic readers are not picking up ANY fault codes, even when a coil pack is disconnected!

 

[teamzr1]

Is this 05 C6 totally stock or is it possible in the past it was tuned as if so the tuner could have turned off certain DTCs ?
If stock, is it possible the DTC reader you're using does not support all GM enhanced DTCs ?
With key on, engine off, does the check engine light come on and stay on ?

At the least with 1 coil pack unplugged should cause misfires and that would trip DTCs for that
Really need is a full OBDII scanner and look the engines' feedback sensors and the fuel injectors pulse width times
along with the long and short term fuel trims and see if they report within normal range

Using a fuel pressure gauge connected to the fuel rail, (on end of left fuel rail) should report 58 PSI

Also assure the MAF and throttlebody are clean and no leaks from aircleaner to TB

Keep in mind the early C6s using the LS2 also had its own PCM model, which was not used once LS3 was used so
maybe the code reader you're using doing not support that PCM.

 

[Mr. Cricket]

My 2005 LS2 C6 convertible suddenly picked up a misfire due to massive overfuelling, but isn't throwing any codes or check engine lights.
Any suggestions as to the cause and who could sort it?
Conventional diagnostic readers are not picking up ANY fault codes, even when a coil pack is disconnected!

Where are you? Parts USA in Bredbury, Stockport can do it

 

[monty]

Where are you? Parts USA in Bredbury, Stockport can do it

I agree Parts USA, they have got the correct reader. They did my C7 Z06 that had a slight misfire and sorted it no problems.

 

[MrNoisy]

What's your location? I have a 2005 C6 (E40 PCM, 1 yr only) and have HPTuners which I use to make tweaks to my tune. I'm not suggesting for one second i'd be willing to play with anybody elses tune (and couldn't without additional licence) but I am willing to hook it up and read what you have going on. We can certainly very easily check if you have any DTC's disabled and see what is going on fuel and misfire wise. If you are not aware already it is an absolute piece of **** to disable DTC's on these cars. If it's missing that much it's noticeable then it should be chucking codes. Hunch - Vac leak...

 

[Godzilla]

Thanks for all your replies. I've sold the car on as is to a very knowledgeable veteran Vette owner and I'm sure he'll be able to sort it.