1st Gen P0170 lean bank after cat theft attempt

Thanks to this fourm I was able to crawl underneath to test the O2 sensor with multi meter.. it tested at 13.1 oHms.

Last Oct cat theft was attempted. I had shop weld the pipe back together.
before weld the P0170 lean bank was on (check engine light)

after welding the engine light went off for a little while, then came back on .
It seems to have a bit of a rough idle sometimes. and occasionally I smell exhaust.

funny thing when the rains hit hard in california there was a few weeks where the check engine light went off.

I couldnt tell if this cut was clean though the exhaust pipe.. I am attempting to test it using some High Heat JB Weld.. i hope that isn't a mistake ?

I saw a video of a guy using a shop vac on the blow setting into the end of exhaust pipe and spraying soapy water on the manifold ( cold engine) to determine where leaks are.

any help would be great! I am a bit over my head and need to get past smog in a couple months. (wont happen with the light on)

really glad I was able to rule out the oxygen sensor!

thank you!

 

I’ve used a vacuum before to find leaks, but they are usually really noisy and make it difficult to track the sound. An air compressor is better, just make a plug that you can put the air line on at the tailpipe and then feel around for air leaks. You don’t need much psi, maybe 10?

 

Ah air compressor! I like that idea! I dont have one available. I am hoping that little slice just before the cat is the culprit.
I won't know unless i reset the check engine light and see what happens.

 

There’s usually some black soot around leaks. It’s hard to tell with that one, but you could just run the truck and hold your hand near it and see if you feel anything. The larger leaks are easy to find.

 

I need to get some ramps. I can just barely squeeze underneath.
i put the high heat jb weld over that little gash.

I dont really have a good spot to work..mostly doing it on the street when I get some room.
good ideas!
thank you

 

I pulled it up on the curb again so I could get back underneath somehow i found the "downstream" ox sensor.. (the one closets to the muffler- is that downstream?)

I tested that- it tested fine. darn!
still not bad for a girl that only learned to change a tire and oil growing up 50 years ago ..

I did notice (not sure why i didnt have it on saturday) this leak coming from gasket I presume.

It isn't supposed to be wet like this is it?

I am trying to save my pennies and I dont think I could do a repair like this on my own.. especially after reading some other posts here on the fourm.

dang.. my old 2000 ranger is needing some work.. and now the 98 taco . ranger was my baby..then someone stole her.. and because health issues I have alot of medical appts at a distance. was lucky to get the tacoma just before the pandemic.. and sure enough.. highway patrol found the ranger!

it's great to be learning new things with these two old beauties : )

 

Yes, it does look like that gasket is bad.

The thing with the sensors, is that they can test ok, but might not work. I know the sensors are expensive, but replacing them with Denso/OEM (these sensors are brand / quality critical, cheaper ones don't work) would be the next step once you've ensured that the exhaust isn't leaking.

 

what would be the easiest way to test exhaust being an aging woman with health challenges..some days are easier than others

I guess fire it up and put my hand under that gasket?

I read the receipt from when the check engine light happened before and that mechanic used a "smoke " machine and determined the EGR solenoid valve was bad.
when I asked him about it a few months ago he said " if it runs fine I wouldn't worry about it.. those are really hard to diagnose" I need to be getting a smog in the next couple months though so I need to find the source.

would an exhaust/ muffler shop be a better option to diagnose leaks in manifold exhaust etc?

I am willing to try and find it myself ..I have very limited experience though.. willing to learn .
thank you

 

I doubt the gasket itself is causing an issue. Mine looks about the same right now. It's on the list, but low priority since it's not throwing a light. That cut you still had in the exhaust pipe is more likely an issue, as exhaust lost between the sensors would read as inefficient cats.

You may have to reset the ecu with a code reader once you get the exhaust pipe resealed, and wait for all the monitors to run before you head in for a smog.

 

I was trying to find an app to reset the code .. I have windows 10 and an old

$11 elm327 bluetooth OBDII OBD2 diagnostic scanner CAN ELM 327 scan tool check engine light car code reader

elm327 I got from Amazon end of 2019 for $11. I was able to get it to work before and now not sure but I am having a time finding an app that will work with windows that doesn't cost alot. I do have an iphone 8 that is old someone gave me.

I put high heat jb welt over that cut.. but from the looks of the photos i took using a shop vac and soapy water..there are alot of bubble around that jbweld "patch"

I also sprayed soapy water on the gaskets and they blew some big bubbles!! really big! i didn't have much room to get a better shot..the curb was in my way so I and to really squeeze underneath .

I looked up the gaskets and they seem to be about $7 each.

would the little leaks in gasket cause the p0171 code? what you are saying makes sense to me about the gash before the cat causing it to throw a code.
and just curious about the gaskets.

is the high heat jb weld any good? my plan was foiled! plan was to use the high heat jb weld I had on hand.. then reset the code and see if that temporary patch had solved the problem. then get it a permanent fix.

will you be replacing those gaskets yourself?


thanks.

 

The EGR valve can get stuck, especially with all the oily gunk that makes its way through the PCV valve. Did the EGR get replaced? If not, that is probably the cause of your problem. Sometimes you can just clean them, but at that point and the age of it, it might be worth it to replace it. There are also a bunch of vacuum lines that run to it, and at about 15-20 years of age they start to break down and fail. Leaks on these can actually cause the EGR valve to not function, so it could be as simple as replacing those vacuum lines. This is why your mechanic said they are hard to diagnose.

This is most likely where your problem is. Small leaks on the exhaust pipe will not typically cause P0170. Are you sure that was the code? It wasn't P0171 was it? The Factory Service Manual actually doesn't list P0170 as a fault code, just P0171 (system too lean) and P0172 (system too rich).

P0170 is for fuel trim malfunction. There are many things to check, not just exhaust. Have you checked your MAF? I know you are responding to this code because of the theft attempt, but it could be a coincidence. You still want to solve your exhaust leaks, but it could just be one part of the problem and sent the fuel trims over the edge that threw the code.

https://www.google.com/search?q=P01...V_8C9oQrQIoBHoECA8QBQ&biw=1918&bih=1447&dpr=1

 

This is alot of great info. Thank you! I did have the EGR valve replaced a couple years ago. I was also looking at those rotting ole vacuum hoses thinking I should replace them myself.

I was thinking about getting the same size and the auto store and then cutting them to fit. I can't remember why I didnt do it. I think I also looked online and I believe they sell them as a set. ?

I also notice the smell of exhaust sometimes when driving..another reason I was thinking about the exhaust.

I got lucky today and drove it over to a small independant muffler shop (place that put the rebar and cables around the cat) and was just gonna have them look at the gaskets and give me a quote. He ended up fixing that little gash just before the cat. He also reset the engine light. and told me what you just said that often those little leaks are normal.

I am going to "assume" the EGR sensor is still ok since it isn't very old. Less than 5 years. (fingers crossed) Over the next couple days I will look up MAF and what that looks like.

I can also check into replace those vacuum lines myself.

I think you are RIGHT! It must have been P0171. He even told me today at the muffler /exhaust shop and my brain already lost it.

Thanks for the homework!! This is good! much appreciated!

 

NZ !! Great artwork!!!

 

I wonder any wire harness damage from the cat being stolen that could be causing more problems.