Cat Cleaning Citric & Oxalic Acid. CO Emissions

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landtoy80

landtoy80

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North Front Range, CO
Emission tested the 94 LC 417,000 mi and got a FAIL.
1st test O2 unplugged = 6.8 NOx
2nd test plugged in old O2's and added 1 gal denatured alcohol to 5 gal gas 7.3 NOx

I checked the temp of the cats after hwy driving and the cats were the same temp as the exhaust pipes off the manifold so there is no heat being generated my the cats.

I unplugged the O2's a year ago do to rich/lean CEL. Either the O2's are way out of spec (but there is no code after plugging them in) or the alcohol didn't work.

Full test:
1st test
HC 1.8827 Limit 2.0 Passed
CO 17.4154 Limit 20.0 Passed
CO2 720.5633
NOx 6.8742 Limit 4.0 FAIL

2nd test
HC 1.1103 Passed
CO 11.5356 Passed
CO2 731.1560
NOx 7.3277 Failed

I am now going to try and clean the cats with citric acid and oxalic acid.
I have read several good results using the acids.
http://www.tundrasolutions.com/forums/intake-and-exhaust/227234-p0420-p0430-hail-mary-pass-cat/
http://www.subaruforester.org/vbulletin/f88/catalytic-converter-citric-acid-bath-p0420-91379/


I will clean the O2's with the acids too.

I dont have a way to get the solution to flow so I will just soak it and agitate the solution every so often.
 
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1. You probably need new 02 sensors so quit being cheap and replace them.

2. You can get a solution over the counter the will do the same this as your acid concoction it's called Cata-clean. Dump that in a 1/4 tank of gas and it'll clean the O2's and the element in the cats.
 
Cats done cooking. One cat looks good, other cat has a stain or built up in the center of the catalysts about the size of a silver dollar. The rest of the catalysts looks like the other cat. Not sure if another soaking is needed. In the original test study, it seam that the two acids were not mixed so there was a soak in the citric acid and a soak in the oxalic acid so that would be 16 hrs of soaking vs just on 8 hr of the mixed acids. If I dont pass emissions test and there is some reduction in NOx, I will do a second soak.

Nuts, when installing the O2's I found that one wire in plug connector has corrosion on it (green) so I will have no idea if doing a acid soak cleans them or not. The corrosion was not too bad and may of just started cause it cleaned up very easily. They have been unplugged for a year or so so it may or may not been the cause of the lean/rich CEL.

Its off to emission testing next week.
 
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Just curious, did you ever test the O2 sensors per FSM to see how they are functioning?
 
I did not. I gave up testing them. Once they start throwing rich and or lean codes I either unplug them or replace them. Its strange, they will throw codes, I will unplug them and later (weeks or months) plug them in and they will work for months then and then start throwing codes again. You will know when they completly dead as the motor will run so bad it will hard run or start.

These O2's had rich and lean codes when I unplugged them. I will test them per FSM. I drove over 100 miles today with no CEL.

I had planned on never plugging them in again but I moved to an emission testing area so I needed to see if they are just plugged or not working.
 
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landtoy80, just curious… At what point do they stop testing emissions in CO on 20 + YO vehicles? I am not trying to be a smart arse just curious.
 
Understood… Thanks Man!
 
Be careful with the oxalic acid. It is highly toxic.
 
Tested again and almost passed.

Failed on NOx but only by .1444 GPM

Something worked to reduce the NOx as it went from 7.332 to 4.1444.
Not sure how much a lightly corroded O2 connector plug affected but you would think there would of been a CEL but who knows.

3rd test ... 2nd test ... 1st ......... Fail
HC 0.9648 ... 1.1103 ... 1.8827 ......... 2.0
CO 18.6311 ... 11.5356 ... 17.4154 ........ 20.0
CO2 723.6856 ... 731.1560 ... 720.5633
NOx 4.1444 ... 7.3277 .. 6.8742 ........ 4.0
 
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Passed.
Set the timing back to where it was at 3 deg. Aired up the tires to max air pressure 65 psi (one was at 25 psi) others were at 54 psi.
HC 0.5986
CO 9.9442
CO2 555.035
Nox 2.8966

It took two runs on the treadmill so I thought it failed again, they give you a second test if the first fails but when I paid for it I got a pass. The lady was surprised that it passed.

I guess the acid cleaning must of done something and maybe you need to drive to get the residue out of the cat. The acid test did call for a flowing of the acid while the cat was soaking.

I will call this Acid Cleaning of Cats and O2 a somewhat "Yes it works, kinda".
I should of spend more time preparing for the Acid Cleaning buy doing more emissions systems checks but like usual, I got in a hurry and missed a few things. Low tire, corroded O2 plug.

I did the test with fresh G-Oil (vegy oil) with 2 bottles of Motor Oil Saver (oil additive) but it was the 4 cycle small engine motor oil (not sure if its any difference from other G-Oils). The oil is suppose to reduce all emissions.
 
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