I'm curious about it's possible to check/test a clogged catalytic converter reading ALDL data such as: load, BLMs, temperature, knocks, TPS %, etc. in order to replace or not replace it.


If any one know, thanks in advance,


Denis V.

 

well, for the ecms we use in thirdgen's, It's not necessarily easy, or implemented in any way. I suppose you could try one thing, you'd have to put in a thermocouple prior to the cat and always monitor your exhaust temp, I would think a clogged cat would make the egt higher once it got clogged, but it would be something you'd have to watch over a long period of time. Then use a spare input with a patch to put the voltage output of a thermocouple driver into the aldl datastream.

the later P6 style ODB-II stuff monitors cat life by measuring cross counts on either side(why there are 4 o2 sensors on some LT1s and LS1s), and once they see that cross counts pick up on the output, they know the cat has gone bad. Ideally, the back sensors never see crosscounts, becuase the cat should have burned the excess HC and made the exhaust a homogenous stoich mixture.

if you were good with code patching, using the right ecm with a spare input, you could mimic the later style PCM operation.

 

Supposedly you can test for a plugged Cat or exhaust with a vacuum gauge connected to the intake manifold. I imagine you can use a MAP sensor in the same way.

 

If you're looking for a way to tell because of a problem you're having, look at the map. It is a vacuum gauge. Typically, a restricted exhaust will cause the vacuumto fall off at a steady load. Drive down the road, hold the throttle steady at cruise, the MAP value should stay pretty consistant, if the volts start going higher, you have a problem.

If you're looking for a way to have the computer test it, such as OBD2 does, I don't think you can, at least not very easily.