Clogged Cat Issue Video Inside

[Vipervin]

Hi, all. I recently posted about my 2003 Viper feeling sluggish in the higher RPM band. Due to weather, I didn't get a chance to really confirm the issue.

Today, in lieu of a dyno, I decided to do an acceleration run and compare to similar stock 03-06 Viper numbers. After doing a full throttle run in 2nd gear, it's pretty obvious that there's an issue at higher RPM. In the video below, you can see how it hits a brick wall after 5k RPM and I eventually shift around 5500 RPM rather than try to stay on it till redline. The accelerator was down until I let off to shift.

The engine makes good torque and feels strong at low RPM. It doesn't throw any codes. Exhaust outlet temps after driving were identical, but then I realized that the crossover may make this reading null. So, I checked manifold temps 20 minutes later and the passenger side was around 150-155 and the driver's was closer to 115-120.

Any other methods to narrow it down or other issues possible aside from the cats?

Video Link:

https://youtu.be/iIXCcpEYeiA


Thank you

[JonB ~ PartsRack]

Try the "Pants-Leg Dyno" Wear some lightweight trousers

Stand about 12" from Driver's exhasut tip, while someone revs it moderately. Note the pantleg deflections / flappings.

Now do the OTHER side. Compare flapping intensities.

Since 4 cats dont fail simultaneously, the least-flappy cat, especiially if significantly muted, is the suspect side.

Note: Cats are like a toilet...they DONT CLOG THEMSELVES! Feds make em built to last 50K miles.

Failed couple of plugs, failed wire or two, failed coils are common cat-killers. MEEEOWCH!

If you replace or delete cats without repairing the fouling mechanism, you only fooled yourself.

GOOD LUCK

[Grcforce327]

Catalytic converters are against my religious beliefs.

46983

[Grcforce327]

Edited because of no sense of humor by "Country" !

[Vipervin]

Thanks. I appreciate the insight. I do have 47k miles on mine, but I will check the other potential issues also.

[Vipervin]

Did a quick look around and pulled a few plug wires. The one below the oil fill cap started shocking me as I held it. Once I shut the car off, I noticed it was covered in oil. The area around the plug also had oil pooled in it. It appears that someone was sloppy with the oil pour.

The plug electrode looked similar to the others, so i cleaned up the oil and put it back in. The car feels a bit stronger, but still seems to have the top end issue. I'll have to confirm in 2nd where I have traction. This might not be the solution, but could've caused the cat issue.

Pic:
https://ibb.co/BNPTnP6

[JonB ~ PartsRack]

Did a quick look around and pulled a few plug wires. The one below the oil fill cap started shocking me as I held it. Once I shut the car off, I noticed it was covered in oil. The area around the plug also had oil pooled in it. It appears that someone was sloppy with the oil pour.

The plug electrode looked similar to the others, so i cleaned up the oil and put it back in. The car feels a bit stronger, but still seems to have the top end issue. I'll have to confirm in 2nd where I have traction. This might not be the solution, but could've caused the cat issue.


20% of the fuel was not burned on at least that one cylinder bank. You can bet over a short time it ruined the cats on that side. 47K Miles on car/wires/plugs matter. FIX THAT before you add HF Cats. Feds say Cats must last 50K, You used em up anyway!

[Steve M]

20% of the fuel was not burned on at least that one cylinder bank. You can bet over a short time it ruined the cats on that side. 47K Miles on car/wires/plugs matter. FIX THAT before you add HF Cats. Feds say Cats must last 50K, You used em up anyway!

I've always thought it was 80k for the cats.


The Performance Warranty covers repairs which are required during the first 2 years or 24,000 miles of vehicle use (whichever first occurs) because the vehicle failed an emission test. Specified major emission control components are covered for the first 8 years or 80,000 miles (whichever first occurs). The specified major emission control components only include the catalytic converters, the electronic emissions control unit or computer (ECU), and the onboard emissions diagnostic (OBD) device or computer.

Source: https://www.epa.gov/transportation-air-pollution-and-climate-change/frequent-questions-related-transportation-air