small engine cats

[DavidBarkey]

The 3 major causes of "cat failures" is actually not the cat its self but rather bad O2 sensors, Dirty Mass Air Flow sensors , and leaky exhaust manifolds . Understanding that a 5-10 year old Cat. may only be running at 75% efficiency and dropping below the threshold setting a code . Where a new cat will bring it above threshold and "solve the problem ".During my 17+ years in drive clean repair I "repaired" many , many faulty Cat.s by cleaning the MAS and running Sea Foam through the engine and out the exhaust . 1 in the tank and 1 dripped into the intake behind the throttle body . No disassembly required and not a mosquito to be found for miles . lol The other is the broken bolt syndrome not unlike my own truck at the exhaust manifold ahead of the O2 sensor affecting the O2 readings and the mixture as a result . An exhaust leak ahead of the upstream O2 sensor will kill your fuel economy as well . For every pulse out is a vacuum and false air leak in skewing the O2 sensor readings too the lean side causing the PCM to riches up the mixture .
Dave

I run seafoam in the gas 3-4 times a year,will have to try it down the throttle body. I changed the o2 sensors, but have not cleaned the MAS. Thanks


Gordy

Be careful cleaning the thermal resister in the MAS they can be damaged easily . What you are trying to do is remove the dust jacket off the thermal resister . Seafoam down the throttle body need to be metered to a drip like an IV . Too little wont do anything and Too much will choke off the engine or if way too much can hydro lock Ouch the engine . Engine need to be warmed up and held at a fast idle .

Dave