07 Suburban rough idle P0304 code afm delete

[smokymtn65]

So i thought I would start my own thread here. Hopefully for some help to figure out what is going on. As title says Did a delete, using a BTR stage 2 truck cam. And it has been tuned. I have a rough idle and will throw code P0304 after time, Today I drove it in to work 50 miles no code had a bit of rough idle when started but not bad. I stopped for gas and it was more rough after restart. a mile later the stabil-a-trac lit up and then had a pending P0304. one more mile to work and idle was pretty rough and it smells like it's running rich.. I did have and issue after the cam install, my young helper apparently drooped a intake bolt in the intake runner of cylinder 4 head. so it lodged enough it went partially through and the intake valve got bent. I replaced the valve they were very little visible damage the head or piston I seated the valve using compound and mating surfaces were looking good. The compression check afterward was 150 on 4 and 150 on 2 I do not go further since they were so close. I have moved all components from 4 to 2 one at a time to eliminate injector, coil, plug wire, and plug, The computer is triggering to injector by test light in ground side. I used a spark checker and it lights from the coil. All ideas and help Appreciated!! I also has a hot hard start issue after sitting for 20 minutes it will take 2 cranks sometimes to start and smells like raw fuel. Thanks @kbuskill for your input so far. And @randeez as well

 

[kbuskill]

So i thought I would start my own thread here. Hopefully for some help to figure out what is going on. As title says Did a delete, using a BTR stage 2 truck cam. And it has been tuned. I have a rough idle and will throw code P0304 after time, Today I drove it in to work 50 miles no code had a bit of rough idle when started but not bad. I stopped for gas and it was more rough after restart. a mile later the stabil-a-trac lit up and then had a pending P0304. one more mile to work and idle was pretty rough and it smells like it's running rich.. I did have and issue after the cam install, my young helper apparently drooped a intake bolt in the intake runner of cylinder 4 head. so it lodged enough it went partially through and the intake valve got bent. I replaced the valve they were very little visible damage the head or piston I seated the valve using compound and mating surfaces were looking good. The compression check afterward was 150 on 4 and 150 on 2 I do not go further since they were so close. I have moved all components from 4 to 2 one at a time to eliminate injector, coil, plug wire, and plug, The computer is triggering to injector by test light in ground side. I used a spark checker and it lights from the coil. All ideas and help Appreciated!! I also has a hot hard start issue after sitting for 20 minutes it will take 2 cranks sometimes to start and smells like raw fuel. Thanks @kbuskill for your input so far. And @randeez as well

Did you happen to check the constant power side of the injector to make sure it is getting power?

I only ask because you specifically mentioned the triggered ground side which means you could have had your test light hooked to the positive terminal of the battery while checking.

 

[smokymtn65]

Yes I check it as well, It was steady on with key on. Thanks need all the help I can get LOL

 

[smokymtn65]

An update after sitting for 3 hours I started it up and let it idle for a a few minutes the pending p0304 went away and was replaced with a P0300 so guess I will just have to start checking all cylinders.

 

[Geotrash]

Have you checked the fuel pressure at idle on the fuel rail?


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[smokymtn65]

Have you checked the fuel pressure at idle on the fuel rail?


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I had when I was dealing with hard start a little before I pulled right head, it was 51psi on my HF gauge. I do need to check again. THX

 

[smokymtn65]

Have you checked the fuel pressure at idle on the fuel rail?


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I checked it again last night 59psi steady at idle.

 

[kbuskill]

I checked it again last night 59psi steady at idle.

Is this a flex fuel truck?

59 psi is pretty high for a flex fuel engine/pump.

The flex fuel pumps are commanded to 43.5 psi
from the factory.

 

[smokymtn65]

Is this a flex fuel truck?

59 psi is pretty high for a flex fuel engine/pump.

The flex fuel pumps are commanded to 43.5 psi
from the factory.

Yes it is a flex fuel.

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[kbuskill]

Yes it is a flex fuel.

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I wonder if your tuner jacked up the fuel pressure in the tune?

I would think having the higher fuel pressure with the bigger flex fuel injectors could be dumping too much fuel, but I would also think the O2 sensors would realize that it was rich and compensate for it as well.

Someone with more tuning experience will hopefully chime in.

@randeez @swathdiver