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Discussion Starter #1
I just put a new motor in replaced all the sensors still running lean on both banks, at shop put new computer in it with same issue at this point no body can figure it out I have done vaccum check no changes am ready to drive it off a cliff please help????
 

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1) How do you know it's running lean?

2) Have you checked your exhaust system? If you're relying on the O2s, if there's an exhaust leak, it can suck air in, giving a false lean.

3) If you're trusting the O2s, have you replaced them?

But it all boils down to 1. How do you know it's running lean?

RwP
 

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Discussion Starter #3
1) How do you know it's running lean?

2) Have you checked your exhaust system? If you're relying on the O2s, if there's an exhaust leak, it can suck air in, giving a false lean.

3) If you're trusting the O2s, have you replaced them?

But it all boils down to

Have it at the shop and they have it on the scanner and throws codes
 

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Discussion Starter #5
How old are the O2s? What shape is the exhaust system in upstream of the upstream O2?

And what codes is it throwing?

RwP
O2 sensors are new not sure code numbers but both banks running lean been at shop for a while replaced the fuel pump, all new injectors new coil packs and plugs
 

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Discussion Starter #6
O2 sensors are new not sure code numbers but both banks running lean been at shop for a while replaced the fuel pump, all new injectors new coil packs and plugs
Extremely frustrating I have done and put so much money into the truck am at the point of no return need to get it right so I can drive the pisss out of it 🙃
 

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Red Trucker
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Lets back up and start with what year and engine you have. Anything else is random firing conjecture til that is known.
 

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Red Trucker
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2004 dodge ram 1500 4.7 has less than 1000 miles on it
Ok
1. Did you use your same intake manifold? If so, were fresh gaskets/o-rings installed?
2. What is your fuel pressure?
3. Does it run well or does it run like shit/stumble?
4. How old are your cats? Originals?
 

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Discussion Starter #10
Fuel pressure is 60 or something close to that yes new gaskets on intake and yes same original cats, runs ok but it does stumble tested and retested each injectors and replaced the o2 sensor a couple of times thought is was a vaccum leak but did smoke test and nothing replaced the fuel pump because thought it was the issue stumped
 

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What brand O2 sensors are you using? Some aftermarket sensors (Bosch in particular) don't play well with MoPars. OEM is best. I've found in the long run you are better off with OEM sensors despite the higher cost.
 
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Did the replacement 4.7L have EGR? On 2005+ engines the left head would have a drilled passage to the #7 exhaust port. If the port at the rear of the drivers side cylinder head wasn't blocked off it would draw in fresh air in setting a lean code. I would hope your shop could hear this as an exhaust leak though.
Second thought, did they reuse your old exhaust manifolds? Those are typically warped once the clamp load to the cylinder head is released. The cure is to have a machine shop cut the faces flat on both or replace.
The single best way to check for the source of exhaust leaks is to cap the system at the tailpipe & pressurize to 5psi with regulated shop air. Listen for leaks & Snoop(soap/water) the manifolds & exhaust flanges.
 
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