[09 SRT*]

Long story. Have an 09 srt8 that I bought 2 years ago. Raced it hard for months and eventually had lifter failure (120k ish). I replaced the cam with Inertia Motorsports SRT Max plus cam and stock lifters (for people who don't know that cam, perfectly fine to run with stock lifters, springs, pushrods). Now I was a broke college student had a lot going on and complications that I couldn't avoid. Which lead me to driving the car with no tune for months (probably 3k miles). Awful I know, but nothing else I could do. Fast forward I had so many issues trying to find tuning for it, eventually got multiple email tunes from Inertia Motorsports. Even with the tune I had misfires, they recommended I check for bent pushrods, I did and was fine. Checked springs, pushrods, everything visible. Then after car got broken into and my diablotuner was stolen (4 months ago). It's pretty much sat since because of winter. My question is do I go to a local trusted dyno tuner that I found to see if it's a tuning issue (only say that bc idk the reliability of them and kinda seemed off) or finally just take the heads off and see if I bent a valve etc. Or even before all that do a leak down and compression test.
Any ideas or opinions would be greatly appreciated
(and yes I have checked coil packs and spark plugs, tb, haven't checked injectors though just the voltage to them)

 

[FlyersHockey]

I'm not really an expert, and it seems you're actually fairly knowledgeable.

My recommendation would be, if you plan on doing the majority of the work yourself then take the heads off and get started. If it has the potential to be something more time consuming and involved than you're ready for, I'd take it to a reputable local shop.

They'll most likely be able to pinpoint the problem much quicker.

Just my .02.

 

[Steelborn1]

Basics first. Do you have the codes? I’d check compression on the misfiring cylinders first. Try swapping injectors from a good cylinder and see if the miss follows. Could always be in the tune if everything else checks out. Don’t forget fuel pressure too!

 

[09 SRT*]

Basics first. Do you have the codes? I’d check compression on the misfiring cylinders first. Try swapping injectors from a good cylinder and see if the miss follows. Could always be in the tune if everything else checks out. Don’t forget fuel pressure too!

If I remember right cylinder 3 & 8, but other cylinders get codes every now and then. Did compression test early and it was fine. Have swapped injectors already might try cleaning them. Fuel pressure was in spec. Thats what leads me to valve or bad tune

 

[georgiapi]

Unless obvious its a PAITA. Swapping inj, coil, plugs to the other bank probably 1st.
A compression test can lie if a cam lobe is worn changing the open close timing of said valve can give lower or higher reads according if its an intake or exhaust . A leak down test will save you the trouble.
If you suspect a cam lobe/lifter check rocker movement in comparison with others. Pull the fuel pump relay and the starter relay and wire a jumper there to bump her.

Eye balling it a spring's coils will all most be all touching at top dead center. If cold spin her some to make sure the lifters are primed. If bad enough to can see the difference in movement as she rolls over.

This rocker is all the way up. I don't have a pic of one all the way down but those coils will look all but like they are bottomed on a rocker all the way down.

Then there can be a harness issue, or even the engine control module. The shop manual has procedures for meter checking the harness at the pins.

My starter bump momentary switch.

 

[sleeperhemi06]

Swap the ignition coils around to see if the misfire follows

 

[SRT-8Charger]

Sounds like a burnt valve from an improper tune. Do a compression test. Should be 150psi plus. Check for broken valve springs and failed lifters. All the pushrods should be tight after you crank it over a few times. If any are really loose, that's probably your problem.