Fuel pressure is about the only thing that doesn't throw a code.

A misfire causes a bad converter, not the other way around.

Normally, folks do a compression test first then the leakdown. Same tool, the compression usually tells if you need the leakdown.

 

Correct I did not plug in the throttle body. Once the car got up and running and warm I had no misfires but still idled a little rough. I drove it for a few hours with zero problems and zero misfires 2 days later it got really cold and the car started to perform like it did in the beginning with lots of misfires and HP tuner shows one of my injectors not pulsing not sure if that means it's not or just the programs not receiving the signal. It will be warmer in the next few days I will try to troubleshoot some more I'm hoping it's just a new set of injectors that seemed to not work in the cold I still have a rough idle and it works fine when it's warm but when it's cold that's when it seems like it's down a cylinder or perhaps a injector is not working. I did change all the plugs coils and injectors around and still cylinder 3 is the one that misfires badly when it's cold. I plan to use injector cleaner to perhaps clean out the combustion chamber better so I hope the problem goes away when it's warm but I am thinking it is the injectors. As well thanks to all those that suggest ideas. Thanks Dave

 

Check the wiring to the injectors first, are they clean and dry?

Have a look at this from Drummerboy

https://www.chevyhhr.net/forums/clas...w-price-57307/

 

If you switched injectors and still have misfire on the same cylinder it is not the injectors.

Have you ever tested the fuel pressure?

When you say misfire, do you mean a CEL and code? Or, it feels like a miss?

 

I don't see in any of your posts where you have performed a compression test or leak down test.

 

No compression test..Will do. Now that I have cleaned the intake I will do another leak down test. The car did work when it was warm other than a tough Idol which I figured was carbon in the combustion chamber. HP tuner shows misfires and got the code as well also shows PSI in the fuel rail

 

From Mitchell OnDemand:

 

For what is it worth you might try to inject some water in the intake so it will get into all the cylinders. Water is a good cleaner for the intake valves and cylinder. It will remove carbon buildup. I have water injection on mine so it gets water under boost all the time. It wont make difference if you are direct injected or port injected. Fuel will not wash off carbon from valves. If any thing fuel will leave deposits on intake valves. If you install a water injection system you can clean you intake valves and cylinders at will. There are other benefits you get also.
Here is a pic of my intake valves at 226K miles.

 

yes a good idea. i was thinking a 5th injector, fuel instead of water to wash the valves.
i have hptuner so easily done. can't deny the use of water, very clean.

 

Like I said . Gas is not a solvent. It has too many additives in it and you will still have deposits. Try this take a pan put 8oz of fuel in it and heat it. You will find a lot of sticky left overs from the fuel after it boils off.
Water is still the better way to go.