IR thermometer suggestions

[davebugs]

I'm working on a Toyota RAV4 of my aunt's.

 

Had a miss fire (one coil pack and 4 plugs - old ones actually looked o.k.) and it was fixed for a week.

 

Catalyst below effeciency. Seafoam works for a few days.

 

About to try non-fouler but vehicle isn't here so unsur e if there is room.

 

My real question is how high of degrees F do I need to ba able to read before and after cat to see if cat is actually clogged a bit?

[Idasho]

It should be pretty obvious. Pre-cat will be considerable hotter. A properly functioning cat will produce the opposite.

[davebugs]

yea - but what temp gun do I need?

 

Don't know how high of temp reader I need.

[Crazyeights]

In my opinion something that will measure up to 650 - 700 degrees F should work.

[Idasho]

Any run of the mill temp guns will work.

 

This isnt a turbo-diesel. And you are checking temp at idle, without a load on it.

[davebugs]

Any run of the mill temp guns will work.

 

This isnt a turbo-diesel. And you are checking temp at idle, without a load on it.

 

Actually I do have 2 turbo diesels but no need to check either of them. If I suspect a cat problem on either of them that's easily solved.

 

I thought cat's themselves run way hot - like 1,000-1,200 degrees. But I just wan tto check the pipe before and after.

 

HF has a cheapie that I didn't think would read high enough. Reads to 968F onsale for 19.83. So you fella's think that'll do for this Toyota and most gassers?

[Crazyeights]

The HF one should work fine. I have used it many times.

[davebugs]

The HF one should work fine. I have used it many times.

 

Thanks. I ran out of patience to stop there this evening after hitting 2 lowes to find the tool set on sale to be able to see the contents since they aren't listed on the website.

[GeneralDisorder]

The way to check this is to plumb into the O2 sensor port with a pressure guage and check for a build-up of pressure before the cat - there should be almost none. Maybe 1 to 2 psi. Any higher and the cat is likely clogged. Temps are not always a reliable way to check for a clogged cat.

 

Though in every case of a clogged cat I've seen the car would barely drag itself down the road and fuel consumption was heavily impacted. Last one I did was a late model Chrysler van and it struggled to get up to 45 MPH.

 

GD

[davebugs]

I got the IR reader and some of my rechargables are now charging because I think it said they were low. LED screen worked but no laser dot or readings.

 

On this toyota the cat is on the front of the engine jsut after exhaust manifild and between engine and rad assy.

 

Seafoam didn't work. I was gonna pull the second O2 sensor on whichever bank and add a non-fouler. Car has 138k rust belt miles on it. Have to think what heat shield fsteners I'm gonna break and what shape O2 sensors may be in as far as removel. I replacement Walker is like 600 bucks and replacements never seem to last.

 

I may ignore the car until tomorrow. I had assumed cats were under the car.

 

This thing is stupid layout. Throttle body is half way down engine between engine and firewall facing upwards.

 

I try to stick to VW's and Subaru's even for friends and family. But sometimes I get other vehicles that folks ask for help with.

[GeneralDisorder]

The O2 port you want to do the pressure test on is the one before the cat - should be up near the engine if the cat is right after the header.

 

Don't use a non-fouler - get some of these:

 

http://www.ebay.com/itm/251151741085?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

 

They work with more certainty. I've had non-foulers not do the trick on some severe cases. These 90 degree units have the benefit of being able to orient the sensor in any direction that's convenient and then lock down the threaded lock ring. For the price, no need to drill them out, greater effectiveness, etc they are a no brainer. I stock half a dozen of them at all times. These will work with NO cat. Many aftermarket "racing" exhausts come with a similar welded-on 90 degree "bung pipe" for this purpose.

 

GD

[davebugs]

Thanks.

 

I've seen you post about these before.

 

I didn't have the car when I picked up the non-foulers that are in stock local.

 

I'll read the code(s) tomorrow and see if I can get to the downstream O2's.

 

2 up top (one each side), 2 on bottom(one each side). Catalyst bekow effeciency means it's the second one in the stream.

 

Looking like a project for tomorrow. Can't wait to see how disasterous getting the heat shield off will be. Then I can see if access form the top or bottom will be easier.

[GeneralDisorder]

My experience with Toyota's is that they use a flanged O2 sensor and the stock one's don't have threads as the flange is swedged to the sensor body. That makes it impossible to use non-foulers unless it has aftermarket sensors with threaded flanges - I've had to buy new sensors in order to get threaded flanges or order the threaded flanges separately to complete a bung-pipe install on a number of Toyota's. Check the pictures of the sensors on Rockauto for that specific model.

 

GD

[davebugs]

I see the top ones have nuts, and a garage already replaced an O2 sensor so I'm thinking it's one of them.

 

I did find a diagram and it looks like they are all threaded. I'm mostly wondering about access.

 

http://images.search.yahoo.com/images/view?back=http%3A%2F%2Fsearch.yahoo.com%2Fsearch%3Fei%3DUTF-8%26p%3D2001%2Btoyota%2Brav4%2Boxygen%2Bsensor%2Blocation&w=298&h=300&imgurl=cdn.2carpros.com%2Fautomotive_pictures%2F261618_Noname_324.jpg&size=22KB&name=261618_Noname_324.jpg&rcurl=http%3A%2F%2Fwww.2carpros.com%2Fquestions%2Ftoyota-rav4-2003-toyota-rav4-p1155&rurl=http%3A%2F%2Fwww.2carpros.com%2Fquestions%2Ftoyota-rav4-2003-toyota-rav4-p1155&p=2001+toyota+rav4+oxygen+sensor+location&type=&no=3&tt=114&oid=481fba0110189a6151ffaf7ee17723b7&tit=2003+Toyota+Rav4+Problem+P1155+Engine+Performance+4+Cyl+Two+Wheel+...&sigr=1246hr2ve&sigi=11qc0ksbd&sigb=12hsciiur&fr=yfp-t-701-s

 

After I post I'll see if this huge link even works.

 

I don't use rockauto but I will go look for the 01 Toyota 4 cylinder's cat and sensors.

 

Thanks.

[carfreak85]

...Pressure before the cat - there should be almost none. Maybe 1 to 2 psi. Any higher and the cat is likely clogged.

 

Sorry, but I must respectively disagree. On an OEM exhaust system, if you are measuring exhaust pressure before the muffler, cat, turbo, etc. can be anywhere from 15-45psi from the factory. It just depends on the construction chosen by the engineers. Even on a cat-less, muffler-less racing exhaust system, 2psi is really, really good, if it reaches back to the rear bumper... That is why fitting a large diameter, high-flow exhaust system to a turbocharged car can produce such significant power gains on its own, you are creating a large pressure drop across the turbine, encouraging the hot exhaust gasses through the turbo as quickly as possible.

 

One way to check to see if the cat has plugged up, besides GD's pressure test, is to remove the pipe that has the cat in it and shine a light down one end and look down the other end. If you can't see the light reflecting down that short length of tube, your cat is probably toast. If you can see some light, or a lot of light, your cat is probably still in good shape structurally.

Edited November 26, 2012 by carfreak85

[davebugs]

One way to check to see if the cat has plugged up, besides GD's pressure test, is to remove the pipe that has the cat in it and shine a light down one end and look down the other end. If you can't see the light reflecting down that short length of tube, your cat is probably toast. If you can see some light, or a lot of light, your cat is probably still in good shape structurally.

 

While correct, it's unworkable.

 

I live int he rust belt.

 

Stuff will break and it'll be a general pain in the a$$.

 

If it's coming out it's gonna be replaced.

 

Also the desigh of this has the exhaust manifold in it and I wouldn'e be able to see straight through. Both ends are bent I believe so its not like I can even shine in a flashlight and look into one end's bend and look for light.

[GeneralDisorder]

Sorry, but I must respectively disagree. On an OEM exhaust system, if you are measuring exhaust pressure before the muffler, cat, turbo, etc. can be anywhere from 15-45psi from the factory.

 

That's not been my experience.

 

Here's one informative source:

 

http://www.aa1car.com/library/exhaust_backpressure.htm

 

 

From the above linked article on exhaust back-pressure testing:

 

Backpressure readings at idle on most engines should generally be less than 1.5 psi (10 kPa). This will vary somewhat from one vehicle to another depending on the design of the exhaust system, the size of the pipes, how restrictive the converter, muffler and/or resonator is, and whether it is single or dual exhausts. We've seen some idle readings as high as 2.75 psi on a few vehicles, but for most 1.5 psi or less at idle is normal.

 

A partially restricted converter, muffler or pipe may flow enough exhaust at idle not to cause a problem, but chokes breathing at higher engine speeds. So to test this possibility, you need to rev and hold the engine at 2000 rpm. A "good" reading on most engines at 2000 rpm should be 3 psi (20 to 21 kPa) or less. Again, there may be some vehicles that will read a little higher that don't have a problem, but the reading should not be significantly higher.

 

Pay close attention to what the backpressure reading does while you are holding it at 2000 rpm. If it remains steady, chances are there is no restriction. But if the reading gradually increases, it means backpressure is building up and there may be a blockage.

 

If you want to rev the engine higher, say to 4000 rpm and hold it, the backpressure numbers will shoot up. Most stock exhaust systems will show backpressure readings from 4 to 8 psi (27 to 55 kPa), or even higher. As before, if the backpressure reading is unusually high or it continues to climb at a steady rpm, it usually means there is an abnormal restriction causing an unhealthy increase in backpressure.

 

GD

[carfreak85]

Hahaha, well now you've got me curious! And I forgot to even talk about IR thermometers, one of which I've just bought!

 

GD, on the backpressure topic, I have my #3 cylinder tapped for an EGT probe. The gauge isn't working, and I've been meaning to pull the probe out and test it. While I'm doing this, I will test the backpressure of my mostly stock WRX exhaust.

 

On the IR topic, I bought a Craftsman 1:6 IR thermometer. It reads from -4 to 500*F, +/- 3*F from -4 to 20*F and +/- 3% or 7.5*F from 20 to 500*F. Not a wide enough range to take external readings of a hot turbocharger, but plenty good enough to read tires, exhaust, intercoolers, etc.