My 99 vortec 5.7 STINKS, has a subtle miss but no Codes or CEL

[brycebba]

Hey all, like the title says, I have a strange scenario with my 99 Vortec 5.7 It has become really stinky where it started with a gas/rich smell and is now a whole new kind of stank. I noticed that within a week or two of the smell beginning, my oil level went up some and smells like gas. Since the smell has gotten worse and is not a rich smell, it has developed a slight miss/stumble at idle. There are no DTCs or CEL and I have verified the CEL is functional.

Here is pertinent information in order:
-The engine was rebuilt totally at a machine shop 3500 miles ago.
-Had a spark plug wire touch my header and was arcing for a very short period of time. The wire has been replaced about 500 miles ago.
-Rich gas smell started
-Oil level went up a bit and had a fuel smell to it
A few weeks pass and about 200 miles
-Still no DTCs
-Smell has now changed and has gotten worse, no longer smells like a typical rich condition and it does spread and actually burns my eyes a tiny bit
-Slight stumble/miss at idle but runs great otherwise
-No visible or audible exhaust leaks
-Nothing obviously noticeable seen in engine compartment or underneatg
-I don't believe I have any vacuum leaks
-I have cleaned the MAF recently and even subbed in a spare during this with no changes.
-Engine seems to be running hotter than it should at times
-Fuel pressure is great and has hardly any drop after sitting with the gauge on it.
-Today I looked at my torque app (I know but it's all I have) and ran graphs on ECT, IAT, Bank 1 Long Fuel Trim, Bank 2 Long Fuel Trim, B1S1 o2, B1S1 o2. Nothing in my very untrained eye could see anything wrong except the B1 Fuel Trim and B2 Fuel Trim difference that never moved really once in closed loop.

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Any thoughts or recommendations on additional data needed or troubleshooting steps would be awesome! Thanks

Bryce

 

[DallasTahoe]

On your torque app add in misfire counters and drive it around, it may not be getting enough misfires to trigger the cel but atleast you can see which cylinders it’s happening on and when. I had slight misfires I checked valve lash and it was the culprit, no more misfires


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[brycebba]

On your torque app add in misfire counters and drive it around, it may not be getting enough misfires to trigger the cel but atleast you can see which cylinders it’s happening on and when. I had slight misfires I checked valve lash and it was the culprit, no more misfires


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Oh ok. I know it only has select pids to monitor so I will see if I can get to that one

 

[Schurkey]

You can probably expect your catalysts to be cooked, too. Misfire is very hard on the cats.

What are the downstream O2 sensors showing?

Fuel in the oil? How is that happening? Can the injection system spray into the crankcase if the plumbing is defective? Is the fuel mix in the cylinders so rich that raw fuel blows past the rings? If so, the cylinder walls are washed, and the rings are toast. You'll be lucky to hone the cylinders and re-ring after the injection system is repaired.

 

[brycebba]

The downstream o2 sensors got removed at some point with a black bear tune that set them to like 45 or 045 I will worry about severe damage if that comes into play at some point

 

[94burbk1500]

You can probably expect your catalysts to be cooked, too. Misfire is very hard on the cats.

What are the downstream O2 sensors showing?

Fuel in the oil? How is that happening? Can the injection system spray into the crankcase if the plumbing is defective? Is the fuel mix in the cylinders so rich that raw fuel blows past the rings? If so, the cylinder walls are washed, and the rings are toast. You'll be lucky to hone the cylinders and re-ring after the injection system is repaired.

A leaky injector can cause fuel in the oil. System still has pressure when it gets turned off, fuel drips into combustion chamber and pools, as the engine cools the rings contract, fuel seeps into the oil. Saw it on an astro van I had with the 4.3. Might not be the case here, but fuel in the oil isn't always a trashed block.

 

[brycebba]

A leaky injector can cause fuel in the oil. System still has pressure when it gets turned off, fuel drips into combustion chamber and pools, as the engine cools the rings contract, fuel seeps into the oil. Saw it on an astro van I had with the 4.3. Might not be the case here, but fuel in the oil isn't always a trashed block.

Yeah good point. During the rebuild I had the shop install the updated mpfi ACDelco 217-3029 units I hope it wouldn't be having issues suddenly. My fuel pressure gauge has gone from ~60 down to 20psi in 13 hours of being off. Good? Bad?

 

[94burbk1500]

Yeah good point. During the rebuild I had the shop install the updated mpfi ACDelco 217-3029 units I hope it wouldn't be having issues suddenly. My fuel pressure gauge has gone from ~60 down to 20psi in 13 hours of being off. Good? Bad?

My truck is tbi, so I'm no expert on the vortec motors. I wouldn't think that would be an issue though.

 

[Schurkey]

The downstream o2 sensors got removed at some point with a black bear tune that set them to like 45 or 045 I will worry about severe damage if that comes into play at some point

You think you have a misfire, and you're surprised that the computer isn't setting codes when important sensors for detecting catalyst damage have been disabled?

What ELSE did "black bear" screw up?

 

[454cid]

You think you have a misfire, and you're surprised that the computer isn't setting codes when important sensors for detecting catalyst damage have been disabled?

What ELSE did "black bear" screw up?

I wouldn't think eliminating the second pair of O2s would be a big deal. GM did it themselves in 2000, at least for the 454.