Diagnosing Catalytic Converter Issues

[erikvr]

How can one tell if the catalytic converter has reached its end on an 85 1.8 4WD GL?

 

Obviously, there is the smell test (if fumes can be smelled). But other than that, how does one know. And is there just one giant piece to the unit, are there two? I can only find one, but a mechanic told me the one in the front was fine and the one in the back is bad?????? Looks like one giant (and expensive) part to me.

[MorganM]

I really dunno how long the catalyst in side there is good for.

 

What your mechanic is refering to is the second chamber in your exhuast. I belive its called a resinator? The first big chamber is all one piece from your headers upto the resinator. This is yoru "Y" pipe as we all call it. Its your main catalyltic converter and should be fine. They are really tough buggers. The headers and pipes all around the "cat" will rust away before the actuall cat does.

 

Replacing the resinator should be cheaper and easier than the cat. It unbolts from the Y pipe assembly as its own part. A lot of times they commonly refered to this as your 'mid pipe'. It's the resinator and a long length of pipe back to your muffler.

 

I hope this clarifies your exhaust system and you can make a more informed decision on the work you want done.

[rallyruss]

actually a resinator is not a cat. two differnt things. resinators are for noise reduction. nothing to do with emissions.

non CA models did not have the second cat. If I rember correctly from my old 85 gl they used a resinator in place of the cat. but the CA models did have second cats.

 

as for testing a cat.

assuming the car is in good condition. no misfires ect. you can check the O2(if it has one) to see if it cycles properly. if it does and the car still runs dirty then you may have a cat. problem. you can then drill a hole in the exhaust and check the sniffer readings before and after the cat.

 

your car may have air injection. if so that will effect the cat as well.

 

is the car injected or carbed? what kind?

[erikvr]

my car is carbed, EA82, 1.8L non-turbo 4WD. No O2 sensor. Hence my pinch to diagnose.

 

 

actually a resinator is not a cat. two differnt things. resinators are for noise reduction. nothing to do with emissions.

non CA models did not have the second cat. If I rember correctly from my old 85 gl they used a resinator in place of the cat. but the CA models did have second cats.

 

as for testing a cat.

assuming the car is in good condition. no misfires ect. you can check the O2(if it has one) to see if it cycles properly. if it does and the car still runs dirty then you may have a cat. problem. you can then drill a hole in the exhaust and check the sniffer readings before and after the cat.

 

your car may have air injection. if so that will effect the cat as well.

 

is the car injected or carbed? what kind?

[idosubaru]

if it's really clogged it'll get noticeably hot, turn red or glow.

 

i've always disconnnected the converter and let it hang there, go for a nice loud spin and see how the car drives. if it noticeably improves then your converter or exhaust upstream of the converter is the problem. if not, bolt it back up and move on to something else. buy an after market converter and weld it on, that's the cheapest route (i think it is, unless OEM converters are really cheap for your car). i bought a highflow converter brand new from a guy for 25 bucks and welded it right up. taking it to a shop and having a bolt in converter put in would have a been a few hundred dollar affair.

[rallyruss]

my car is carbed, EA82, 1.8L non-turbo 4WD. No O2 sensor. Hence my pinch to diagnose.

ok well your mechanic must have reason to suspect the rear cat. did it fail a test?

 

I just looked it up and alldata. shows all with 2 cats. I thought that was only for CA cars.

 

if thats the case then you have the one where the Y pipe meets and then one behind it a ways.

 

on your car air injection will effect the cat. also loose/worn throttle shafts. and the adjustment screw on the carb(need to drill out a plug to get to it) along with the regular timing/ignition stuff