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PLEASE HELP! FAILED SMOG 5 TIMES - HIGH NOX - Done Everything I Think Of

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PLEASE HELP! FAILED SMOG 5 TIMES - HIGH NOX - Done Everything I Think Of

Old 12-26-2018, 04:06 PM
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Lets see what I can remember from emission testing in Colorado decades ago. CO is partially burnt fuel. So co will be high if it is running rich. HC is unburnt fuel. So if you have a miss hc will be high. Nox is high on an efficient engine- high compression ,advanced timing ,etc. An egr valve is for reduction of nox. It does this by letting exhaust gases into the combustion chamber. Exhaust is cooler than what is going on in the combustion chamber and it takes up space so it reduces efficiency. They also achieve this by reducing compression and running less initial and total timing. Your compression test looks rather high to me depending the altitude you are at. Maybe high compression pistons with a stock cam? Hope this sheds some light on what is going on.

Last edited by rsmdon; 12-28-2018 at 03:53 PM.
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Old 12-26-2018, 04:30 PM
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northoak,

Thanks bud. I appreciate the offer. I may take you up on that. I actually have a 3 port Toyota OEM modulator that I ordered by mistake some time ago. According to the not so friendly and rather gruff smog guy I cannot use that modulator and block off the R port. Whether that's because it won't pass visual or won't function properly was not disclosed to me. I would need to do some more looking at the exact nature of that modulator to see if it would work.

toyospearo,

Thanks! I'll be outta town for the next little while so no rush.

13Swords,

I also thought they looked pretty good. not ideal, but pretty good. But... that creates a bit of confusion in my head. They don't look (to me mind you) like plugs from an engine that's running super lean. I don't know much about the lamdba but it seems to be a trusted source amongst many yotatech folks. Lambda says I'm running really lean, NOx suggests I'm running lean, but plugs look close to the right color, see what I'm getting at here?

Good idea to double check on those jets, I'll do that. I haven't had the chance to try and tune it via lean drop (holiday madness). I'm gonna be outta town for a minute so I'll definitely try that when I return.

That's good to know about the AAP and the #1 cylinder as I'm sure I'll come across that again at some point. I had no idea it would effect that cylinder primarily.


So in lieu of my planned wheeling trip, I'm headed out for some fun in Mexico with some buds. The truck is parked for now but I'm sure I'll be right back elbows deep in it as soon as I return. I'll keep y'all posted.

Thank you everyone for your ideas, opinions, and support.

Sam
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Old 12-26-2018, 07:05 PM
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The only thing better than the lambda to tell you how your engine is running is to get the lambda before the cat. The cat can clean up and artificially lower some of the numbers. It's science vs guessing like guessing what color your plugs are
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Old 01-12-2019, 06:09 PM
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Hello Everybody!

So I'm back stateside and had a few moments to mess with the truck.

13Swords,
I confirmed that the carb does have stock jetting and went through the "lean drop" procedure. Ended up pretty much back where the carb folks had it set. Their setting was 5 5/8 turns out mine is 5 1/2. The carb guy said to try and see if I could get it to idle at 500rpm or below and that if it could its "not that lean". Not sure what he wanted to determine from that but I did it anyways (willing to do almost anything at this point haha) and it would idle below 500. It wasn't happy to do so, but it did it.


So,

Some interesting (or confusing depending on how you look at it) developments through testing and brainstorming are as follows:

1. As I mentioned before, the O2 sensor when tested just reads 0.7V. The signal does not cycle back and forth between 0.2 -0.8 as it is supposed to. In my understanding, 0.7V is the rich side of the cycle.

2. The air injection system is not functioning properly (which potentially shouldn't matter, see below)
- EACV Not responding properly:
When I tested the original EACV it would not switch the flow of air from the "closed loop" through the air cleaner (off position), to the exhaust side (on position) even when the temp sensor is jumped as per FSM. I replaced it and the new one does switch when the temp sensor wire is jumped but not at any other time. The FSM says that it should switch to the exhaust side when the coolant is between 64 - 109 degrees F. It does not do this. Between 131 - 208 degrees F (not sure what happened to 110 - 130 haha) it is supposed to switch back and forth at the bidding of the O2 sensor. Considering the O2 sensor is reading rich you'd think it would keep it on the exhaust side. Alas it does not. there are a few other EACV tests that the FSM mentions that it also does not do properly but I can't say if that's correct because it's baseline seems to already be way off. I think this may be because of a bad thermo switch 1. Regardless, according to the smog guy as well as my logic, this shouldn't really matter because the system is stuck in the off position and isn't adding any oxygen to the exhaust.

3. Thermo switch 1 is likely bad. It also seems to be part of the system for the "outer vent control" on the carb. Do you think this could be part of the problem? I now need to test that.

4.Talked to the smog tech at Yota1. He has been very kind and helpful. Thanks for the tip Yotard! He said that it could potentially be the EGR modulator as we spoke about. He described "the black dot of death" as he called it on the filter. I looked at mine and it does seem to have a spot but I'd say it's more a "brown spot of something". Going to try and replace the modulator just for good measure.

And now last but definitely not least,

5. I checked for vacuum leaks yet again. While I still need to do a smoke test (need to make a block off for the top of the carb so all the smoke doesn't just escape) I did do another propane test. This is where it got interesting.
I went through my normal procedure of putting the hose near any and all places that could have vacuum leaks. No results. Since I have never used the propane method on this truck and actually found a leak (used it on other vehicles with much success) I wanted to see how the engine would actually react to propane enrichment. I put the hose in the top of the carb and opened the valve on the propane bottle slowly until it was all the way open. Nothing. No change in idle whatsoever. So I hooked the nozzle of the propane hose into a vacuum port on the intake manifold. Nothing. No change whatsoever. Weird. Any thoughts on that?

Once again, Thank you all for you help and support both in the past and future.

Regards,

Sam

Last edited by FourEyes; 01-12-2019 at 06:16 PM.
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Old 01-12-2019, 06:50 PM
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Look at how much 02 is in your tail pipe at smog 2.8% My last passed smog check in October was 0.0 and my lambda is perfect 1.005. Your 02 sensor is clearly not working. That should be saying you are lean. Two years ago I failed to a lean 02 sensor and I was 1.1%. You are way lean and it's really clear your 02 sensor is not working the numbers don't lie it's all right there. You are probably going to have to have your carb dyno tuned at a shop. Then you can start checking your smog system after.

Last edited by Yotard; 01-12-2019 at 06:58 PM.
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Old 01-12-2019, 07:16 PM
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Hey Yotard!

Yeah I kinda assumed that the O2 sensor is bad. just doesn't make any sense otherwise. I did read ( http://www.autodiagnosticsandpublish...r-testing.html ) that you can get a false rich reading on the O2 sensor if your EGR isn't working properly but that seems far fetched for me considering I replaced and tested the EGR. Thanks for the reference point on the O2 from the smog test. I wasn't sure how much it was supposed to be. As far as the propane enrichment question, the only thing I can think of is that the mixture is already sooo lean that the added propane wasn't enough increase in fuel to make any difference? The shop I bought the carb from said they tuned it on their carb dyno but I have been looking around for a shop to tune the carb while it's on the truck. So far, no one seems to want to do it.

Thanks again,

Sam
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Old 01-12-2019, 07:25 PM
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I would send the carb back and ask for another, they insist it's right but chemistry says that it's not.

Last edited by Yotard; 01-12-2019 at 07:31 PM.
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Old 01-12-2019, 07:35 PM
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I'm inclined to agree with you. I brought up the subject when I spoke with them the other day. We'll see where it goes.

Thanks,

Sam

Last edited by FourEyes; 01-13-2019 at 12:19 AM.
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Old 02-15-2019, 06:51 PM
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Hello Yotatech!

So I'm back at it and had some interesting results as of late. After thinking about the factors I mentioned in post #24 I did a few things and did some more research.

Thermo #1 Switch and Outer Vent Control:

Because of my suspicion of a bad Thermo #1 switch I did some more testing. I tested the outer vent control as per FSM. The manual says to blow into the vent when the truck is off and it should flow freely. Then blow into the vent with the truck running and no air should pass through. I did this and tested with smoke and air/smoke was always able to pass through. This made me decide to replace the Thermo #1 switch as it is mentioned in testing the functionality of said system.

I was able to track down a new OEM Thermo #1 switch and installed it. It did not have any effect on the outer vent control.

My thinking was that perhaps with the outer vent control stuck open, it was pulling unmetered air into the carb and leaning out the mixture, thus creating my problem. I wasn't able to find any conformation of this in the FSM or the Toyota Carburetor book I have. Still it was a hunch. Then I read the following on a different Yotatech thread:

Nordicwargod:

"Yeah, just looked at an 81 FSM and for CA
The o2 sensor does give feedback to the carb. When the engine warms up, the o2 sensor will send a voltage to the "computer" [if you can call it that]. The carb runs rich by default which is "dirty" and will cause you to fail emissions when the sensor does not work. When the voltage is low the outer vent control valve on the carb stays closed because its lean, when its rich it opens and lets more air come in through the carb leaning things out. It's activated by one of the wires going to a solenoid on the carb. Its that simple. The valve opens and closes several time a minute."



I was not able to find reference to this in the 83 FSM I have but thought that if this is true it would make sense to get my O2 sensor working properly and see.


O2 Sensor:

The very friendly and helpful smog tech at Yota1 recommended a test to confirm that the O2 sensor is not functioning. He said to pull the brake booster hose to create a large vacuum leak while taking a reading of the O2 sensor voltage and see if it leaning it out that much would change the voltage. I did this and unsurprisingly it did not change at all. Next he said to inject propane via the brake booster hose and once again see if it changed the reading. It did not. So that pretty much put the last nail in the coffin for my O2 sensor.

Now the problem became: Why is the O2 sensor not functioning properly? Is it the sensor itself? Or perhaps the wiring to the sensor? I had altered the wiring for the sensor to make it work with my LCE header. This required adding a long wire to extend it. Not wanting to cut into my stock wiring harness, my solution was to cut the female wiring plug off the sensor, attach the wire extension to that (so it stayed in the engine bay) and then on the sensor end of the connection I put a spade connector between the extension wire and the sensor. I learned later that some single wire O2 sensors breathe through a port on the sensor BUT SOME breathe through the wire it self. The tiny space between the wire and housing is actually enough for it to breathe (it sounds crazy I know but I confirmed it with multiple sources). I could not see any port on my sensor so I assume it breathes through the wire. Perhaps my spade connection was limiting this?

To be thorough, I replaced both the O2 sensor (with an OEM Denso) and the re did the wiring connection. Now the wiring connection on the sensor end has the proper wiring connector so the new sensor did not need to be cut at all.

While testing the new O2 sensor it did not at first seem to be acting any differently. I decided that since pretty much the only thing I haven't messed with was the ECM I may as well swap it out with a spare that my friend gave me. After swapping the ECM, Viola! the O2 sensor started cycling! I wasn't entirely convinced that the new ECM had made this happen so I swapped the old one back in and the O2 sensor still cycled! My only thoughts on that were that perhaps the contacts on the ECM were loose or gunked up (looked clean though) and switching it in and out helped. Or perhaps the brand new O2 sensor just needed a little longer to start working? Weird.

So now that the O2 is working back to the outer control valve. While it did seem to have a bit more resistance to air flow I could definitely still blow into it while the truck is running. If I blow alot of air in there I can get the truck to stumble and misfire.

Smog Test:

Even though the outer control valve still didn't seem to be right I decided to go get it tested (unlimited free retests, thank god) It failed but..... the results were interesting:

15mph:

HC: 207 (woah! even more at idle)
CO%: 1.64
CO2%: 14.0
O2%: .3 (much better)
NOx : 1353 (basically same as before)

If you remember from my earlier posts, My HC was always pretty low, my O2% was higher, and my NOx was about the same on the last test. These all resulted in a lambda calculation of 1.146. Way too lean.
With these current numbers the lambda comes out to 0.962 a bit too rich. But my NOx hasn't changed!

Not sure what is going on here.

I did change one other component that I had found to be faulty in all my testing. It is a vacuum switch mounted on the passenger fender wall that has something to do with the deceleration fuel cut system. I'm not quite sure what it actually does for that system but figured that it was worth replacing since it tested bad and I found one that tests okay. Perhaps this could account for my high HC?

It's the one circled below:

Here's what the book says:




So there you have it. That's where I am now in this seemingly never ending saga of smog failure. If any of you out there have any input at all on this or any other of the previous posts please do not hesitate to chime in. I can use all the help I can get.

Thanks everyone in advance for any help you can provide!

Regards,
Sam

Last edited by FourEyes; 02-20-2019 at 12:24 AM.
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Old 02-16-2019, 03:34 PM
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It looks like you are using NGK iridium plugs...I didn't notice you mention the gap. If you are using the book gap of .031, you could try Denso IW16 iridium plugs and a 180 degree Superstat. The larger plug gap (.044) will give you a better burn. And, I think the cooler thermostat could lower your NOX...but, I'm not an emissions expert. https://itstillruns.com/causes-high-...s-7619425.html
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Old 02-18-2019, 04:15 AM
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It's unusual to get high nox levels when rich. Usually that means you have a timing problem (too advanced) or your egr is not actually functioning. I know you replaced a lot of the parts but I would test the egr per the fsm. Glad you got the lean condition fixed.
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Old 02-19-2019, 01:33 AM
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Thanks for the replies!

Sorry I'm slow to respond. Had some internet difficulties the last few days.

Chuckross1957,
I am using NGK iridium plugs. I've had good results with them in the past so I decided to stick with the same style after the engine swap. I do have the gap set at the stock setting I believe but I'd actually have to check to be absolutely sure. That's good to know about the Denso plugs! Thanks for the heads up! Since the HC levels are new and are so pronounced but the plugs haven't changed I don't really suspect them as the problem. I am also running a 180 degree thermostat. Not sure if this is the same as the Superstat you mentioned, I'll look into it. Thanks again!

Yotard,
I also think it is quite odd. It definitely raised the smog tech's eyebrow. He was slightly intrigued despite his usual reluctance to get involved (HaHa). The timing is 5 degrees before TDC with the vacuum advance cut and advances to the first unnumbered mark with the advance engaged as per FSM. EGR has been replaced and tested as per FSM. The original EGR tested as per FSM as okay but the smog guy told me it was borderline so I replaced it with a new OEM EGR. The new one tests much better and made a significant improvement in NOx. Just not enough. I'm planning on running through the EGR test again, checking the timing (for the millionth time), as well as redoing a few other tests now that the O2 sensor is working just to establish a new baseline. Thanks, yeah I'm glad the lean issue seems to have partially subsided but still confused as to it's new "rich" condition. I'm still being cautious and keeping the truck parked for now.

Thanks again guys for your support and advice. I'll keep ya posted.

Sam

Last edited by FourEyes; 02-20-2019 at 12:25 AM.
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Old 02-19-2019, 05:35 PM
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HC does not indicate rich or lean. See post # 21.
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Old 02-19-2019, 05:50 PM
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Originally Posted by rsmdon
HC does not indicate rich or lean. See post # 21.

His lambda of .962 is what says he is rich
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Old 02-19-2019, 06:26 PM
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Sorry Yotard I did not make that very clear. In post #29 the OP stated - HC 201 woah even richer. What I meant is that higher HC indicates a miss not if the engine is rich or lean. Also in post #31 he says the timing is set 5 degrees beyond tdc . I dont know if this means before or after tdc. His pickup has an o2 sensor? Does that mean it has a feedback carb?
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Old 02-20-2019, 12:23 AM
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rsmdon,
Sorry that wasn't very clear. I do understand that HC is unburnt fuel but had always thought that was from a rich condition and/or a miss. I did a little reading and I now see what you are talking about. Thanks for straightening that out for me. As to the "even richer at idle" comment, that just meant that the HCs were higher, like around 500. I now see that doesn't necessarily indicate a rich condition so I'll look into that further. Based on the lambda I calculated I assumed that the lower O2% and the higher HC in combination created that. But after playing with the calc a bit I see that it is mostly the 02% and the HCs only had a very limited effect. When I wrote "beyond" I meant to type "before". Sorry, I wrote that post after an especially grueling day in the shop and was pretty out of it. HaHa I know this stuff is complicated enough without my exhausted ass making it even more confusing. Yes, the 83 trucks (CA at least) have a single wire O2 sensor. It feeds info to the very basic smog "computer" (ECM). In my understanding these are not feedback carburetors and the sensor/ECM mostly just adjust the smog equipment such as the air injection and such. That said, the post I mentioned in post #29 indicates that they potentially have some "feedback" like qualities. I have not heard this mentioned anywhere else and am yet to confirm or deny it as the outer vent control as mentioned above is kinda tricky to test accurately.

Yotard,
Thanks for clarifying the rich condition.

Regards,

Sam
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