BajaRunner

FIXED!!!!!! Got new Cat and O2 sensor. Nox went from 966ppm to 0ppm


Tried to smog today, didn't pass due to high NOx. I think I need a new cat, even though its only 4 years old? It only has 31,000 miles on it!?

EGR is working correctly, from what I have gathered. I cleaned the crap out of it, and tested that it functions with testing the vacuum at the top of the EGR when warm and RPM > 2500.

Both high speed and low speed test failed with high NOx and low CO! The tech said something about it running lean.

HC(PPM): 34ppm max is: 95
CO(%): .03 max is: .52
NO(PPM): 966ppm Max is 386ppm

The high speed test is about the same exact readings except the HC and CO went down.

I have a lack of power still, and I feel it might have something to do with the cat being bad, clogged or whatever.

The EGR temp sensor has soot on it, confirming the EGR is opening.

BajaRunner

EGR Modulator might be going, but I honestly don't know if I'm testing it correctly. Its not labeled so I don't know if its hooked up right either.

If I put the "R" port directly to vacuum, and rev the engine, while testing vacuum at EGR, it kind of jumps all over the place...in fact, vacuum is higher when the RPM's are low.

tried4x2signN

I don't have NOx, so I don't think I can help you...

I just want to offer, are your plugs the correct heat range, and is your converter a Toyota cat? (from what I understand, Toyota has has/had the highest quality of platinum. A friend told me when the cat picken was good, scrap dealers wanted Toyota cats, or were paying more for them...)

tim a.

Nox is formed by high combustion chamber temps.If your cat was bad you would most likely be failing all three gasses,but not always.Check cooling system,thermostat,fan clutch operation.With the lack of power I would honestly look at fuel pressure regulator.That would cause a lean condition if stuck closed.

sb5walker

If iron EGR tube that leads into plenum is hot when motor at op temp & rpm at 2500 then EGR is working.

Other things to check are ignition too advanced, vacuum leak, low fuel pressure (clogged fuel filter, bad press regulator, wires to pump corroded), clogged injectors, out of range air meter. Check that there are no cracks in the bends of the rubber air hose between air meter & throttle body.

For the injectors the only in-the-tank products worth trying have polyether amine. Only two that still have it that I know of are Red Line SI-1 Complete Fuel System Cleaner and CRC's "Guaranteed to Pass Emissions Test Formula". Techron, Gumout Regane & BG44K no longer have it. Stuff works good.

BajaRunner

The cat was replaced but not with a Toyota....

My mechanic buddy told me that the aftermarket ones usually are cheap and the metal that converts the NOx usually goes first in them. Can anyone confirm this?

The fact that EGR is most likely working, it then also could be a fuel issue? I do have a misfire when idling. My mechanic friend also told me he thought I had a lean misfire...but has never mentioned the fuel issue. (Well he told me to put 2 bottles of injector cleaner in a 1/4 tank of gas).

The fuel filter is brand new, but its been bugging me since I didn't do it myself. I can see that its new though, but I am really hoping the person who put it in didn't screw with it.

The air meter seemed to check out fine via the FSM test. Same with the ECT. I'm thinking it might be a slightly clogged injector in one of the cylinders?

The fact that at both 15mph and 25mph tests the NOx was WAY off the charts, wouldn't it conclude that it would be something else besides running a tad lean (hot combustion) and the EGR maybe not opening all the way or whatever?

I still think that the cat plays a large role in decreasing the NOx out of the tailpipe.

sb5walker

There are enough signs that it is running lean to focus on that first. Lean running=high nox. Even a new cat may not be able to convert all the nox created from lean running. Most injector cleaners don't do anything. Among the in-the-tank products, polyether amine is the only chemical that has a decent chance of making a difference. Check closely for vacuum leaks. Check fuel pressure & volume.

How many miles on the O2 sensor? Is it a Denso or NTK (NGK)?

BajaRunner

Thanks for your help. I have read a few threads that you've posted on and so I've gained a lot of information from you

Ok. I have no way of testing fuel pressure. The regulator isn't dripping gas through the vac line or anything, thats the only test I've done. I've replaced all the vac lines, 1 by 1. I have also used a water spray bottle and a propane torch to look for vacuum leaks. My vacuum gauge shows a high, steady (15") vacuum reading as well...(not sure if it would be low if there was a leak or not?)

The intake tube appears to be good. I cleaned the plenum out and replaced it with a new gasket.

The O2 sensor is a Denso, it looks like the original. I tested the heater circuit and the alternating voltage of it through the diagnostics box. I may try replacing it regardless. I have 144k miles.

Maybe I should order 2 bottles of the Red Line SI-1 Complete Fuel System Cleaner?

Like I said as well. I do have a misfire, but only in neutral when trying to hold the idle steady at about 2500 to 3500 RPM. I don't notice it when driving or under a load.

BajaRunner

Another thing is that my water pump, thermostat, radiator, radiator cap and coolant is all new.
I don't think my engine is running hot, but I really don't know. The temp gauge in the cab reads right down the center @ operating temperature.

Seriously, here is a list of new parts:
Head, valves, gaskets, fuel filter, water pump, entire cooling system, TPS, plugs, distributor cap, rotor, wires, headers, muffler, tail pipe, PCV, vacuum lines.

Cleaned:
EGR system, plenum, TB, IACV, EGR temp sensor

Checked:
Timing (5* base, 12* advanced), mechanical timing, valves (exhaust were tight), compression test (160 across the board), Air flow meter, ECT, O2 sensor, TPS (new), all VSV's, TVV, vacuum system.

The only things of my concern are: O2 sensor, Cat, Injectors and fuel pressure...all of which could cause NOx problems, I'd imagine

BajaRunner

Another thing to note:

The head gasket blew sometime before I bought it. I've read that coolant in the cat will foul it pretty quick.

Also, when I plug the tailpipe with my foot, the engine cuts off quick. Could this be a good indicator there is too much backpressure in the exhaust, being caused by a clogged or fouled cat?

sb5walker

This post may help with the fuel pressure testing: https://www.yotatech.com/forums/f116.../#post51210586

It is possible for an O2 sensor to still switch okay (what you tested in the check connector) but for the readings to be inaccurate. 144k is a lot of miles for an O2 sensor and a new one might be needed. If you get one, get another Denso. Check sparkplugs.com and using the Denso part # from there search amazon for denso and the part number - that might be a bit cheaper (sparkplugs has very good prices but expensive shipping).

Assuming EGR is working properly and you have no vacuum leaks nor air leaks in the air hose, then I think clogged injectors is next the most likely cause of your lean running. Red Line's SI-1 is a very concentrated product. It contains 30-50% PEA. Using one bottle in 2/3 to 3/4 tank will probably clean the injectors quite well. If you get a second bottle you can add 1/10 bottle at each subsequent fill-up to further clean the injectors. The stuff really does work.
http://www.toyotanation.com/forum/sh...72#post2868772

Don't confuse combustion temp with coolant temp. Even if combustion temps are high from lean running, if the radiator and water pump are functioning okay the thermostat will still keep coolant at the normal operating temp.

Yes, I've read the same thing about coolant in the cat. But fix the lean running first not only to pass emissions but to protect your exhaust valves from burning and to put less heat stress on the head gasket.

If you do buy a new cat, I've had excellent luck with my Magnaflow direct-fit. Sure, it won't last as long as an OEM but then it's only like one tenth the cost. It should work fine for 5 years or so. You can get the part # from their website & then find a good price on ebay: http://www.car-sound.com/

scope103

One thing to consider is that your plenum (or the EGR pipe inside the plenum) is so clogged that even though the EGR valve is opening, nothing is going into the plenum. sb5walker suggested the temperature test; is the iron pipe (which connects at the plenum to the tube inside the plenum) hot? If not, disconnect the EGR line from the plenum pipe, and pull the plenum pipe out. If it is covered with "crud," you'll probably need to remove the plenum and clean it out. A messy, time consuming job, but doesn't cost anything and can't be done "wrong."

BajaRunner

Alright. I'll try getting my mechanic buddy to see if he can test the fuel pressure first.

In the meantime I'll try and hunt down some of the good injector cleaner. (I've used Seafoam, Lucas, STP already heh). I've also seafoamed the engine 3 times. If that doesn't work I'll just pull out the damn injectors. Send to witchhunter?

I'm actually unsure about the P and R ports on the vacuum modulator (the two that face forward and go to the throttle body). They aren't labeled on the modulator so I dont know which is which. ;/ Thats the ONLY thing I am uncertain on the EGR system. If I wasn't getting EGR gasses though, the EGR temp sensor would send me a code 71 like it did when I first got the truck. (EGR valve was stuck)

Being that the NOx was so high at low and high RPM/Speed, I could imagine its not EGR related. However I do agree that I have a lean mix/misfire as well.

BajaRunner

Thanks Scope!

I actually did this 2 weeks ago. I had a code 71, and cleaned the entire EGR system.

I pulled the plenum off completely and cleaned. Took me a few bottles of Carb cleaner, a wire brush and a coat hanger. The port that ran down the length of the plenum was full of black goo. No more code 71 now!

Just re-checked the timing, and the idle is definetly not smooth. The timing is also jumping around. I guess thats due to the unsteady idle. I'll recheck the TPS again I guess.

BajaRunner

Can anyone instruct me to figure out which side the R port and P port are on my EGR modulator? I don't want it to be something stupid like that.

The vacuum diagram on my hood shows the EGR modulator, with the P port on the left side, and R port on right side. I assume that it is showing a true orientation of what it actually would look like on the engine?

See:


So I should connect the right modulator port (R) to the second to front port on the TB, correct? Just making double sure.

Lastly, reading other people's high NOx posts, I see that their max allowable NOx is in the 900's... mines way down in the 300's.... Could a lean mixture really screw me up that bad?

BajaRunner

And once again, another thing to note: The truck runs extremely well when warming up. Once it warms up to operating temperature, it just lacks power, punch and is still sluggishhhhhhhhhhhh ;(

BajaRunner

Well, I got a new cat put on. The old one looked OK inside actually. But, California laws got stricter in 2009 and most likely the old one wouldn't have been able to keep up. We'll see again when I go try and smog it.

I am still working on the lean misfire condition. The O2 sensor is in the mail as well... (Rockauto OEM Denso part was only $55 plus $5 shipping).

BajaRunner

WooHoo!!

The cat and O2 sensor fixed the problem! The smog station was freaking out on how clean my vehicle was. They've never seen a car pass with 0 NOx.

So today:
For 15mph/1600 RPM:
HC: Measured: 4 Avg: 34
CO%: Measured: 0 Avg: .06
NOx: Measured: 0 Avg 74

And nothing changed @ 2500 RPM.

BajaRunner

I am still feeling the engine is running rough, and have followed the procedures by sr5walker in this post:
https://www.yotatech.com/forums/f116.../#post51455996

It runs best during warm up (closed loop). The only thing left to swap is the VAFM. I am going to test the resistance again and do a dynamic check with opening the flap.

Since I've changed the TPS, cat, O2 sensor, all ignition, timing, yada yada yada, I have no clue on what else would be causing it to run worse at warm temps. SINCE its changing when warming up, and I've tested the resistance of teh ECT sensor, couldn't I rule that guy out?

I'm also confused about what O2 sensor I got. I got an "OEM style" Denso plug that I looked up through sparkplugs.com. I don't think my truck is originally a CA emission truck. It only has one O2 sensor before the cat. But, since I am in CA I decided to buy a CA O2 sensor. (Part # 234-4052). A non CA emissions front plug is also the same part#, but there is also ANOTHER part # (234-4072 ). I ask this question because the new O2 sensor (which seems like the most common part #) is much smaller than the one I pulled out!! No codes, and the car runs the same as it did before. Does anyone know which part# they use for non CA O2 sensors, or does it matter?!

BajaRunner

Here's my new O2 sensor next to the old. Mentioned in the post above, I got the part # from sparkplugs.com and bought the same part # on rockauto.

No CEL, and I passed smog, but I don't know if this is correct or not? If I have 1 O2 sensor that means I have federal truck right and not CA?