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2007 Chevrolet 3500 Silverado Classic LWB crew cab,dually, Kennedy dual pumps, , Donaldson filters
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Discussion Starter · #1 ·
Hello All:)
Wanted to check here with the experts. As title says , changed spark plugs, and wires. All the plugs on the passenger side showed excessive rich fuel air mixture ( black coating) Black smoke from exhaust. Extreme rough idle, hesitation on acceleration.
Will be changing cap and rotor, however do not think that is all the problem. Have not changed the MAP sensor, or the coolant temp sensor.

To my way of thinking ," good or bad" I believe the problem area is the injector on the left side of the TBI when looking down on it from the front , causing the passenger side bank
to all be showing an overly rich fuel mix. Engine has approx.150,000 miles on it . TBI had one injector changed way back when I had a great mechanic. All the other sensors are original. ( 599,990 miles original) Used a jumper wire and got I believe a #23 code. Oxygen O2 sensor open circuit, no activity. Or IAT sensor open circuit. This vehicle only has the MAP sensor.
Some other thoughts and or suggestions welcomed, before we start throwing parts at it.:rolleyes:

Thank You.!(y)
L8R
 

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Ronald Reagan fan
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5,124 Posts
I’d probably check your ground wires on the intake manifold and replace the terminals if necessary.Another thing you can try is add a couple new ground wires from the thermostat area to the firewall and from the firewall to the chassis.

One other thing I did on a truck like yours with a tbi engine showing no activity for the O2 sensor was grind down the exhaust pipe near the sensor and install a muffler clamp on that grinded area and run a wire from the muffler clamp to the chassis.If your O2 sensor is a 1 wire sensor it depends on a good ground to function properly.After doing these few ground wire replacements no codes appeared after that.
 
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Premium Member
2007 Chevrolet 3500 Silverado Classic LWB crew cab,dually, Kennedy dual pumps, , Donaldson filters
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Discussion Starter · #3 ·
I’d probably check your ground wires on the intake manifold and replace the terminals if necessary.Another thing you can try is add a couple new ground wires from the thermostat area to the firewall and from the firewall to the chassis.

One other thing I did on a truck like yours with a tbi engine showing no activity for the O2 sensor was grind down the exhaust pipe near the sensor and install a muffler clamp on that grinded area and run a wire from the muffler clamp to the chassis.If your O2 sensor is a 1 wire sensor it depends on a good ground to function properly.After doing these few ground wire replacements no codes appeared after that.
Thank you will check the grounds, the O2 sensor is three wire, ground incorporated into the wiring harness.
I find it hard to believe a ground problem would cause the passenger side cylinders to be extremely rich on fuel air mixture. Ground problem I think would effect the entire engine. But I've been wrong before.

Thank you!
L8R
 
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Ronald Reagan fan
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No problem.I’ve had those tbi assemblies apart a few times in the past.There’s not much to go wrong inside them.The exception would be a broken regulator spring or a hole in the diaphragm.

Since you had one injector changed I’m just wondering if it’s flowing too much fuel on that side because the 4.3,5.7 and 7.4 tbi engines have injectors with different part numbers so they do have different flow rates.

Are the spark plugs in good shape?I find acdelco rapidfire to be a great plug.
 
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Premium Member
2007 Chevrolet 3500 Silverado Classic LWB crew cab,dually, Kennedy dual pumps, , Donaldson filters
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Discussion Starter · #5 · (Edited)
No problem.I’ve had those tbi assemblies apart a few times in the past.There’s not much to go wrong inside them.The exception would be a broken regulator spring or a hole in the diaphragm.

Since you had one injector changed I’m just wondering if it’s flowing too much fuel on that side because the 4.3,5.7 and 7.4 tbi engines have injectors with different part numbers so they do have different flow rates.

Are the spark plugs in good shape?I find acdelco rapidfire to be a great plug.
Like I said in the first post, new plugs A C Delco, new premium silicone wire set.. Will be new cap and rotor after trip into parts house. Fuel filter changed.

This problem just came about. One injector changed was years ago, had been running fine.

Thank you.!
L8R
 

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2007 Chevrolet 3500 Silverado Classic LWB crew cab,dually, Kennedy dual pumps, , Donaldson filters
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Discussion Starter · #6 ·
Like I said in the first post, new plugs A C Delco, new premium silicone wire set.. Will be new cap and rotor after trip into parts house. Fuel filter changed.

This problem just came about. One injector changed was years ago, had been running fine.

Thank you.!
L8R
Bump. Anyone any thoughts or suggestions Thanks
 

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1997 GMC K3500 dually 4L80 4x4
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That's an interesting situation as each injector feeds two cylinders an each bank. If it's really all four cylinders on one bank with a problem, but no problem on the other, I would look more at exhaust. Like the heat riser stuck shut? Just a thought. Good luck.

Mac
 

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1998 Chevy dually crew lifted, 6.5 hx40
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Have you changed the cap and rotor yet? Take a look at the old cap and button for wear. While under there check the distributor for play. I would Definitely change the cap and rotor… new plugs and wires are only as good
 

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2007 Chevrolet 3500 Silverado Classic LWB crew cab,dually, Kennedy dual pumps, , Donaldson filters
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Discussion Starter · #10 ·
I’d only use standard copper plugs for that 94. Ac Delco or autolites…. No split fire, or platinum junk.
Reply to all of you.
Mac. Yes Sir only the passenger side cylinders, old plugs extremely black. Pulled O2 sensor & cleaned SEL not on now.
Click Got cap and rotor , and MAP sensor yesterday, replaced plugs with ACDelco none of the other stuff

Not my only vehicle so work on it when my disposition allows. :rolleyes: I am sure you all understand our good friend Murphy

Thank you
 

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2007 Chevrolet 3500 Silverado Classic LWB crew cab,dually, Kennedy dual pumps, , Donaldson filters
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Discussion Starter · #12 ·

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1998 Chevy dually crew lifted, 6.5 hx40
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Make sure you have signal at the plug. Very well could be a cut wire, pinched, burnt, etc. could also just be a bad o2, or Partially clogged catalyst in the converter with that mileage.
Also, did you erase the code? O2 sensor take a much longer drive cycle than other sensors. You could swap sensors and look for a change. Or replace them. I know the prices of everything has gone up but should only be $20 sensor on this vehicle. Hope you get it figured out
 

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2007 Chevrolet 3500 Silverado Classic LWB crew cab,dually, Kennedy dual pumps, , Donaldson filters
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Discussion Starter · #14 ·
Thank you
L8R
 

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1997 GMC K3500 dually 4L80 4x4
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If there is a valve with either just a weight and clock spring or a vacuum actuator and rod on the right exhaust manifold right below the doughnut, It may be stuck shut. These were used instead of efe grids to prevent throttle freezing. If it's stuck shut, it will restrict and cause your symptoms.
 

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2007 Chevrolet 3500 Silverado Classic LWB crew cab,dually, Kennedy dual pumps, , Donaldson filters
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Discussion Starter · #16 ·
If there is a valve with either just a weight and clock spring or a vacuum actuator and rod on the right exhaust manifold right below the doughnut, It may be stuck shut. These were used instead of efe grids to prevent throttle freezing. If it's stuck shut, it will restrict and cause your symptoms.
Dont think there is, but will check.
Thank You(y):)
L8R
 

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2007 Chevrolet 3500 Silverado Classic LWB crew cab,dually, Kennedy dual pumps, , Donaldson filters
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235 Posts
Discussion Starter · #17 ·
Dont think there is, but will check.
Thank You(y):)
L8R
Mac daddy (y)
Just walked past the burb, nothing but pipe under the flange and donut both sides down to the converter , Converter was gutted years ago. Nothing inside. Appreciate the thought process. I figured each injector feed each bank of cylinders, but I am not the expert.

Thanks again

L8R
 

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1997 GMC K3500 dually 4L80 4x4
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Good check, the other thing that comes to mind now that I think about it, is leaking fuel pressure regulator or injector O rings. You can check by taking off the air cleaner, cleaning off the injectors and whole tower above the throttle body, then cycling the key without starting for two seconds at a time to run the fuel pump, or run the fuel pump from the prime connector and look around the injectors, fuel pressure regulator etc. and see if there's fuel leaking, It would normally be drawn in the engine with the engine running and make for a rich condition but you wouldn't see or smell fuel leaking.
 

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2007 Chevrolet 3500 Silverado Classic LWB crew cab,dually, Kennedy dual pumps, , Donaldson filters
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Discussion Starter · #19 ·
Good check, the other thing that comes to mind now that I think about it, is leaking fuel pressure regulator or injector O rings. You can check by taking off the air cleaner, cleaning off the injectors and whole tower above the throttle body, then cycling the key without starting for two seconds at a time to run the fuel pump, or run the fuel pump from the prime connector and look around the injectors, fuel pressure regulator etc. and see if there's fuel leaking, It would normally be drawn in the engine with the engine running and make for a rich condition but you wouldn't see or smell fuel leaking.
Good thought. (y)
I will check it out.
Thanks

L8R
 

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Premium Member
2007 Chevrolet 3500 Silverado Classic LWB crew cab,dually, Kennedy dual pumps, , Donaldson filters
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Discussion Starter · #20 ·
Hello All
To all of you who submitted ideas, and suggestions, Thank You. (y)
Finally got around to replace the dist. cap and rotor. Dont know how that engine even started. Terrible corrosion inside the cap, rotor mostly burnt off.

Just goes to show check the simple things first. :rolleyes:

L8R
 
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