How to test a catalytic converter on the vehicle

2 ways to test a catalytic converter is with a heat gun & by pressure.this test shows it is burnt out and not pluged. When you do the heat test you need the o2 sensor in so it doesn't dump fuel in to the engine because it can't tell how much fuel it needs without the o2 sensor also get the vehicle up to normal operating temp before you do the testing.

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[Nessaja1]

1st method i agree, 2nd method is a totally waste of time, don't you know how to read scan tool??? all the information you need is there, you just gotta know where to look it up :)

[jones1inc]

@Nessaja1 The scanner don't always list it on all cars. Also there are other things that can set the same code like multiple 02 sensors you should always double check your work along with the scanner otherwise you will start replacing parts that don't need to be replaced.

[isantimn]

how long should i let it run before testing?

[jones1inc]

@isantimn 10 min.

[DJDevon3]

@Nessaja1 Gotta love all the OBDII owners. Try working on something older than 96 and see how effective your scanner is.

[1MtnBoy]

I can remember 98 octane still around when I was a wipper-snapper, I can also remember doing valve regrinds and ring jobs on a regular basis too, something most shops no longer do anymore ( for some good reasons too). Aaah the good old days of opening up the points, retarding the timing and trying a colder plug after Goober resurfaced the head .030 or bored it .020 over.

There are some definite benefits from low compression ratios and a quicker burning fuel as opposed to high comp & octane.

[1MtnBoy]

Be careful of praising the mighty octane god too much it has a dark side ! (R+M)2 is only rating the fuels resistance to knock. The higher the octane, the slower the burn during combustion. This slower burn leaves more time for carbon deposits to form. Almost all of Ford vehicles for example are labeled 87 octane to reduce carbon formation. Many EFI systems rely on a knock sensor to control timing w/CKPS circuits. You do not want carbon effectively raising the compression ratio.

[DJDevon3]

@craigkorb Yup I agree. Higher octane helps with pre-detonation. It can help if you're having a trivial misfire issue. Knowing about octane can certainly be handy in a pinch. :)

[DJDevon3]

@Nessaja1 No offense intended but that sounds like someone's point of view who is very young and never worked on an OBD-I car. Some OBD-I cars don't have live data ports. On a related note some MECS or EEC systems do have live data ports but still no scan ability. This video will be very helpful to DIY owners especially pre-1996 ones but will work for any car. Please educate yourself before saying it's a waste of time. Good video.

[1MtnBoy]

@imjustpassinthru pre-OBD-II vehicles should be pre-conditioned prior to a smog test etc. a good brisk ( not ballistic ) drive for 5-10 mins is usually enough for most older cars. Some Oxidation cat's on older cars can take a lot of punishment but take a while to heat up and stay hot. You shouldnt see any of the exhaust or cat glowing orange after a romp or yes it may be reducing flow creating excessive heat. If the substrate up front starts to melt it will block exhaust flow.

[1MtnBoy]

@DJDevon3 Yup, old school, gimme a DVOM a continuity tester and a couple of T-pins to back probe. I'll tell you exactly what circuit is not operating properly. Several of the imports were using Bosch EFI, the 280Z had the Bosch L-jetronic EFI in 1975 with No OBD at all. I had to use a DVOM on everything all the time, TPS, MAFS, OX, CKPS etc. you have to know the basics first before the scan tool data stream can make sense.

[1MtnBoy]

@craigkorb Actually I was referring to the low quality of the refining process in unbranded gasolines, Not the Octane rating, sorry.

there is a maximum sulpher content allowed by the EPA in motor fuels. Major name brands typically refine the sulpher to a lower level than is required to allow for higher quality and reaction with proprietary additive packages used, such as Techron.

it is the excessive sulpher in the fuels (like Thrifty ) that is the source of the problem.

[craigkorb]

@1MtnBoy amen! i did my own research, i get more for my money with 93 grade gasoline, over the 87 grade. i try to tell people, but everyone thinks their car shouldn't run on higher octane concentrations. WHATEVER PEOPLE, hahaha!

[craigkorb]

@vanda219 thats pretty common in mechanics, hahaha!