Catalytic Converter

What is a catalytic converter?

A catalytic converter, also referred to as a 'cat', is installed in your engine's exhaust system, it is designed to convert toxic gases and pollutants to less toxic pollutants.

What type of catalytic converter is used on Astro/Safari vans?

Three-way:

    1. Reduction of nitrogen oxides to nitrogen and oxygen: 2NOx → xO2 + N2(precursors to acid rain and smog)

    2. Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 → 2CO2

    3. Oxidation of hydrocarbons (unburned and partially burned fuel) to carbon dioxide and water: CxH2x+2 + [(3x+1)/2] O2 → xCO2 + (x+1) H2O (a combustion reaction)

Are they all the same?

When they started installing them on OBD2 vehicles, the requirements increased, so don't put one from a GEN1 A/S van on a GEN2 or GEN3 van. High performance universal catalytic converters are available and are usually the cheapest choice for replacement. You can also get direct fit converter for a bit more money. Usually the cheapest is to buy the universal and have it installed at a muffler shop.

My cat died, what could have caused it?

The main causes of catalytic converter death are contamination, meltdown/overheating, faulty sensors, and road damage. The cause(s)/problem(s) need to be repaired before replacing the failed converter.

      • Contamination - Coats or plugs the working surface, rendering it unusable.

        • Excessive oil consumption or active leak

        • Excessive fuel additives(once in a while is ok, not every few tanks)

        • Gasoline additive MMT

        • Silicone sealant used in exhaust(silicone good for 700°F and exhaust=1200°F)

        • Internal engine coolant leak

        • Oil additives

      • Meltdown/Thermal failure - usually caused by raw/unburned fuel entering the exhaust

      • Ignition system problems, spark plugs/wires/distributor(cap/rotor/drive gear)/coil/ICM.

      • Leaking fuel injector/regulator

      • Severe misfire conditions

      • Thicker than recommended oil viscosity

        • Excessive oil consumption

        • Engine coolant leaks

      • Faulty sensors/components

        • O2 sensors - off-center calibration, sluggish, silicone contamination

        • fuel injector - leaking or metering too much fuel

        • MAF sensor - Rare but can affect the mixture

        • Vacuum hoses - Affects the proper mixture

        • EGR valve system - Faulty increasing exhaust temperatures

        • Exhaust manifolds - Leaking

        • Spark plugs - Incorrect plug, wrong tip or heat range

Does my replacement catalytic converter require a break-in period?

According to some manufacturers the answer is yes. And as it doesn't take long, it wouldn't be a bad idea even for converters that don't specifically recommend it. http://www.easterncatalytic.com/education/tech-tips/proper-break-in-can-prevent-future-problems/

    1. Start engine(don't rev engine) and let it idle to warm up.

    2. After 5 minutes, increase the engine speed to 2500 RPM and hold for 2minutes.

    3. Allow engine to cool down.

I'm getting a P0420 code, what does that mean?

See the P0420 page.

How do I test if my catalytic converter is working properly?

There are a few ways to test for proper functioning of the cat.

      1. Temperature - Because of the chemical reactions in the converter the temperature will increase through the converter if it's working properly. Using an infrared thermometer http://amzn.to/2qkVT6k you can measure the input temperature and the output temperature, should be about 50-100f temperature increase. If the converter is contaminated or blocked, you won't see these temperature changes.

      2. Engine vacuum test - Normal gauge reading should be between 16 and 21 inches, increase the engine RPM to about 2500, watch for a low reading, or the pressure to steadily drop. Could indicate a blockage. See Vacuum Gauge Reading

      3. Temporary exhaust leak test - If the converter is clogged, you will notice an increase in performance by opening the exhaust before the converter. Temporarily remove an upstream o2 sensor, or loosen the manifold flange, and go for a very short test drive.

      4. Exhaust system gauge - Exhaust gauges are available that connect to the upstream o2 port, exhaust back-pressure would be less than 3psi.

If I convert to a carb setup, can I keep my 3way cat?

Nope, because closed-loop engine control systems are required for proper 3-way catalytic converter operation.

Should I remove my catalytic converter?

Only if you want to make the world a worse place and violate the law. While there may be legitimate reasons to remove a catalytic converter, I can only think of 1 possible reason(travel in areas with contaminated fuel) and performance isn't one of them. The newer high performance cats are going to cost you maybe(and that is a big maybe) 1% horsepower, usually at the top end, hardly worth fussing over.

    • It is a violation of Section 203(a)(3)(A) of the 1990 Clean Air Act in the USA for a vehicle repair shop to remove a converter from a vehicle, or cause a converter to be removed from a vehicle, except in order to replace it with another converter.

    • Section 203(a)(3)(B) makes it illegal for any person to sell or to install any part that would bypass, defeat or render inoperative any emission control system, device or design element.

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