04 stumbles only when warm

[Crazyike]

Hey guys, I have a late 04 that has had a stumble after driving on the interstate for quite a while. It was fairly minor and didn't seem to effect performance at all. It 95% of the time went away if i let the truck sit for a bit.

Then around Thanksgiving last year it ran awful when I started it first thing in the morning. So i check my FICM and sure enough my voltages were in the 30's.

I ordered a 58v from Vivian@ Quick Tricks and installed it in December. That fixed the cold start issues, but it still felt like it had a miss when it warmed up on the interstate.

I had hoped it was possibly stiction, so i switched to T6 Rotella and Rev-x. I also changed fuel filters and a new thermostat as i could only get to 176 degrees on the interstate.

It felt like it might have helped the problem but I think it was just me trying to justify putting $250 worth of Oil and filters in my truck.

I had put up with the rough idle for about 2 more months thinking it could be injectors and I decided to take it to a dealer to have a balance test. When i took the truck to the dealer the miss was gone completely and their test was a bust.

So I have been trying to search for people with similar issues as me and i came up with perhaps the ICP sensor. My voltages where swinging from .7 - 1 on my CTS when it would stumble. I replaced the sensor 2 weeks ago and it did not help any.

The miss is getting much worse and is now apparent anytime the truck has reached operating temp.

Looking for some help.

Thanks

[dannyboy950]

You may want to check the throttle plate on the intake. The 03 and early 04's had a throttle plate and actuator, mid 04 they did away with the actuator but left the plate in jammed in the wide open position.

On a few trucks I have found this plate to have moved partially closeing off the intake restricting air flow. Some were actually flopping around causeing random rough idle/stumbles etc. In 05 the plate was removed. A possibility, altho rare.

[Crazyike]

Dannyboy, I will check that.

Forgot to mention, i have no codes other than my FICM over voltage.

[Crazyike]

Morning Bump

[Crazyike]

I removed the butterfly on my intake and also cleaned the EGR valve which was dry in the bottom section, but was oily in the top section. Is that normal?

I have an EGR Delete and a new Oil cooler on its way already.

It seemed to run better today, I tried to run it pretty hard and I couldn't get it to stumble like before. Can the EGR valve cause it to run rough like that?

Forgot to mention I'm getting a ICP low voltage code if i do a hard acceleration now. I can clear it and do another hard run and it will come back.

Any thoughts?

[Crazyike]

Monday bump