Topic: Emissions fail, advice?

[andykrow]

New motor failed NOx somewhat spectacularly. Here in CO this is a dyno test. Results are in GPM (Grams per mile)

HC 0.1397 / 4.5 Limit
CO 0.8557 / 45 Limit
NOx 8.4991 / 6  ***BIG FAIL
CO2 467.0672 ***No limit on CO2, no idea if that's a high number or not

They gave me a graph of the readings tied to speed, and it is apparent that NOx is spiking in the upper third of the acceleration curve range. (No RPMs on the graph, just speed, but you can clearly see how the car moves through the gears. I do not know if the tech was flooring the pedal, hence WOT, or being gentle with it. Seemed to moving through the gears somewhat slowly but I was behind sound proof glass so I couldn't really tell. But it is, like, really spiking. Not even on the chart until the upper 3rd of the acceleration curve, and then top of the chart.

So it seems I am running lean. I plan on replacing all the vacuum hose, testing EGR, backing timing down to 0 or so. I am debating on if I should get into the AFM, and richen the mixture screw and/or the gears. I probably will seeing as how I have so much room to play around with on HC.

Anyone have any other thoughts? I do have a 261C in there and I hope it isn't screwing me. BUT, it does not seem to be a lean idle condition. It's really spitting out NOx at 3k+ rpms. (I think.)

[Toyotadon]

Check EGR first.  It could be failing to work at that RPM, so make sure to test it completely.

Do you ever hear the engine pinging at higher RPM and load?  If so, you could have carbon deposits, a timing control issue, or something else causing detonation.

Are you saying you have a higher temp thermostat installed?  NOx is created at high temperatures, and cooling system "problems" can contribute to failure.

HTH

[andykrow [OP]]

No, sorry on the confusion, the 261C is a cam from Engnbldr. Lately a lot of people talking about lean idle conditions because of it.

I never hear pinging with this motor. It is a new rebuild, only around 300 miles on the clock so far. It runs amazingly well, from a driving perspective.

How would I go about testing the EGR at the higher RPMs? Doesn't the motor have to have a load in order for it to work properly? So I would need to road test it somehow?

EDIT: looked at the FSM and system does not seem to need to have a load to test the EGR. I'll check this out first.

[andykrow [OP]]

The motor does not seem to run hot. Sits just shy of halfway on the temp gauge like most 22re's are supposed to. I know there's a big sweet spot on that gauge, but it seems to be fine. Even so I put the heat on during the test like Big Mike's sticky says. Didn't seem to matter.

[Gnarly4X]

andykrow,

Have you pulled the spark plugs to see how the mixture is firing?

Gnarls.

[andykrow [OP]]

Okay, egr valve fails the idle vacuum test where it should nearly kill the motor. I applied vacuum to the valve and nothing happened. No block off plates. Next I noticed that the lower vacuum nipple on the EGR  pipe was totally open. It should be connected to the bottom of the modulator. Not sure if that would cause faulty valve operation. Ran out of time to test, will see if that solves it tomorrow. 

[andykrow [OP]]

andykrow,

Have you pulled the spark plugs to see how the mixture is firing?

Not yet. I may pull them tmrw.

One more thing, the vacuum on the vsv that connects to the the fuel pressure modulator was hooked up to the charcoal canister. I think this is totally wrong. Shouldn't that vsv have manifold vacuum on the other side? And the charcoal vac line should connect to the E nipple on the throttle body.

I really need a vacuum diagram for this thing....

[Gnarly4X]

This is an 1986..

[Gnarly4X]

andykrow,

Have you done a compression check?

Gnarls.

[Snowtoy]

I really need a vacuum diagram for this thing....

From my '85 FSM

[emsvitil]

A working EGR system will reduce NOx.

Also, the design of the EGR system needs some backpressure to work.

For smog tests,  I add a restrictor plate after the cat to get some backpressure...........

[Gnarly4X]

andykrow,

Have you disconnected the battery since you fired the engine?

If not, you might consider disconnecting the battery to allow the ECU to reset.  The disconnect time is usually a topic of debate, but I'd disconnect it for about 10 minutes.  I would also make sure ALL electrical components are turned off... radio, fan, lights, etc. before reconnecting the battery.

I have no idea as to the what it takes to completely reset the ECU on a 1980's 22RE.  I also don't know how much drive time it takes for the ECU to "relearn and reprogram" itself as it re-analyzes the sensor input after an ECU reset? 

Gnarls.

[andykrow [OP]]

does anyone know if it is possible to tell from the vin if a truck is federal or California? Basically I'm trying to figure out how to hook up to the fuel pressure vacuum nipple. My truck has a vsv that has an electrical connection mounted to the firewall just behind the intake. I was thinking that was the vsv that the cali trucks have. But then I found a picture of 4crawlers hoses and his vsv mounts to the valve cover.

Anyway thanks for the diagrams you guys!

Gonna get back at it in a minute here...

I will definitely unhook the battery. I was thinking of running out my tank of gas and putting 91 in there, and I'm sure that would give the ecru time to relearn.

[andykrow [OP]]

Really wish I had more time to be scientific with this and do changes one at a time and see how it goes. Unfortunately my tags expire on Thursday so I have to get it to pass emissions before then. I am just going to do a bunch of stuff and hope it helps.

This morning before it started raining I drilled out the mixture screw on the AFM and adjusted that down 1.5 turns. Factory was 3 turns out. I hooked up the FPR directly to manifold vacuum, as it was apparently never hooked up correctly. (It went to a vsv and from there to the charcoal canister...wrong!) I also have the hose from the bottom of the EGR modulator going to the EGR pipe nipple that is just before the valve, like it is supposed to. It strikes me now that that was a massive vacuum leak as it was just wide open before.

Immediate driving impressions are that the idle is smoother and more steady after warm up. More importantly, I seem to have found a bunch a low end power. I can get the truck moving easily in first gear with ZERO gas pedal, and in second gear at 1k rpm the truck accelerates smoothly whereas before it was really lugging and not happy.

Unfortunately I have no way to know what of the above changes did this.

After I hooked up the EGR modulator correctly I did the vacuum test and it still did not work. With the engine off I can hear the valve moving as I apply vacuum so I think at least that part of it is working correctly. IDK what to do on this front. It strikes me that when this opens up at idle you are basically making a huge vacuum leak which would be the cause of stumbling or stalling, and that is definitely not happening at all.

My plan right now is to get the vac hoses swapped out once this rain stops, get the timing down to 0, and open up the AFM gear and move it one click rich. I will then drive out this tank of gas, put 91 in it and give it another run through the sniffer. If it fails after that I will pull the EGR valve and give see if it isn't clogged up, and make a baffle like emsvitil mentioned.

I am having a hard time believing a malfunctioning EGR is causing the crazy spike I was seeing in NOx. Sure, EGR will reduce Nox but that much? I have known CO trucks to get through emissions with EGR disabled so I don't think that is my main issue. Sure, EGR could get me through but that may just be a bandaid.

[andykrow [OP]]

@emsvitil

Thinking more about that baffle, have you tested with and without? I do not understand why the EGR would need back pressure. It seems like once the valve opens manifold vacuum would suck the exhaust right in, pressure or not. Or is there some sort of exhaust scavenging at work? (Bernoulli's principle?)

[Snowtoy]

I am having a hard time believing a malfunctioning EGR is causing the crazy spike I was seeing in NOx. Sure, EGR will reduce Nox but that much? I have known CO trucks to get through emissions with EGR disabled so I don't think that is my main issue. Sure, EGR could get me through but that may just be a bandaid.

Likely a combination of things causing that high of NOX levels.  Getting everything hooked up and working correctly, along with setting the timing back to stock, should get the NOX levels down.

Did you pull the egr valve and clean the piping?  The small stem pipe usually gets packed with carbon.  If it is clogged don't try to remove it, they tend to snap, best way is to use a small drill or wire and work out dig out the carbon.  Spraying/dripping carb cleaner, seafoam, or gas on the carbon will help it break it up some.


Also check for any cracks in the intake plumbing, under WOT the cracks could open up allowing unmetered air in, the accordion elbow is usually where the cracks occur.

[andykrow [OP]]

Good info. I didn't pull the egr valve yet, it a bit of a pain to get to. Truck is going through emissions right meow, will see how she does. If it fails again I will get that valve out and see what's what. It's definitely running better after some tweaks, hopefully that gets it done.

[andykrow [OP]]

Well, failed again. NOx better, 7.3 / 6 instead of 8.5/6 and the graph is no longer pinning the top of the chart. It's possible on the first test it was way worse and they just couldn't measure it :/

Next step is get the EGR system to work. Should have done that in the first place. Hopefully I can resurrect that valve. I do not want to pay $175 for a new one...

[Snowtoy]

Yah that little tube on the EGR plumbing is a PITA, the threaded fitting usually fuses to the egr tube, learned the hard way trying to remove them and clean them out.  It takes a bit of patience to clean one out, but time is cheap compared to the cost of new.

Did you reset the timing to stock?

[andykrow [OP]]

I actually had it stock for the first test, 5 degrees BTDC with the test connector in. For this one I put it to zero, so less advance compared to stock. Should help lower NOx.

After this test I got a little more HC, but it is still really low. I might go another click rich in the afm. Actually these emissions test are kinda like a cheap dyno pull. Sorta helping me tune the thing. Or that's what I am telling myself so I don't get raging pissed off.

[Snowtoy]

Good way to look at it, as running lean is bad for the engine, and cheaper than buying a wide band O2.

[Gnarly4X]

Does the 261C with 6 degrees of overlap, per engbldr spec, cause a lean fire condition?

I believe my newly rebuilt 22RE is running a lean mixture (based on spark plug readings)

andykrow's newly rebuilt 22RE is running a lean mixture (high NOx per emissions test)

Years back, when a guy who was seriously testing cam profiles for is 22RE reported that the 261C "caused a lean fire condition".

This may be coincidence, have nothing to do with the cam profile, or caused by one or more conditions or components.

I'm considering removing the 261C, and install the stock camshaft to simply eliminate the camshaft potentially causing the lean mixture I believe I'm experiencing.

Gnarls.

[andykrow [OP]]

Well, got the egr out, cleaned it up and verified all passages are clear, and had a nightmare getting it back in but it is in. Still no love when applying vacuum. I am sure the diaphragm inside opens up - throttle body cleaner flowed freely between when I applied vacuum.

Next step, exhaust baffle.

I am not quite ready to say the 261 causes a lean condition. I need to get the egr system running and then see how emissions is doing.

Am considering getting a wide band o2 so I can really know what is happening.

Back to wrenching!

[andykrow [OP]]

I should point out that from my wrx days, one would never increase flow without corresponding work on the fuel map. Granted, on a turbo the consequences of going lean can be worse, but I think it would be hard to say the 261 is at fault. My nox spiking seems to happen in the 3k + range. I think if I truly am lean that could be attributed to the higher flow from the head and exhaust.

I should also point out that my previous truck, with the 252 and open exhaust, just barely passed emissions with 5.7/6 allowed. I don't know if those numbers are truly high, or if that is some arbitrary number set by Colorado.

[emsvitil]

@emsvitil

Thinking more about that baffle, have you tested with and without? I do not understand why the EGR would need back pressure. It seems like once the valve opens manifold vacuum would suck the exhaust right in, pressure or not. Or is there some sort of exhaust scavenging at work? (Bernoulli's principle?)

Not back to back.   I just squeaked thru a smog test, and the next time after I added the restriction it passed easily.    The lack of backpressure happens with a catback exhaust replacement...........

The modulator needs the backpressure.      I don't have my FSM at the moment..


Snowtoy,   show a picture of the modulator with the EGR valve.     I think you'll see that backpressure helps with the opening of the valve.

Or it's more backpressure helps force exhaust thru the valve..............

[emsvitil]

Ok,   scroll up.

Snowtoy already posted picture of EGR with modular.   

The backpressure helps the modulator............

It closes off the 'T' that has a vacuum escape at the bottom.   

[Gnarly4X]

I actually had it stock for the first test, 5 degrees BTDC with the test connector in. For this one I put it to zero, so less advance compared to stock. Should help lower NOx.

After this test I got a little more HC, but it is still really low. I might go another click rich in the afm. Actually these emissions test are kinda like a cheap dyno pull. Sorta helping me tune the thing. Or that's what I am telling myself so I don't get raging pissed off.

I don't believe that messing with the mixture or ignition timing to trick the ECU to reduce NOx is a good idea just to pass emissions testing.  How much time does the emissions testers give you to correct the out of spec test?  Are there any penalties?

The 1985/86 22RE is designed to meet Federal EPA standards and certifications, and other emissions requirements.  Lean mixture AFR issues and high NOx are not uncommon for these engines, and other engines as well.

The challenge is to diagnose and then fix WHAT is causing the high NOx reading.

Gnarls.

[Gnarly4X]

Ok,   scroll up.

Snowtoy already posted picture of EGR with modular.   

The backpressure helps the modulator............

It closes off the 'T' that has a vacuum escape at the bottom.   

I don't understand how more exhaust back pressure is going to affect the mixture to go richer?  I ran a DT header and free-flow exhaust on my 22R with EGR valve and the spark plugs always looked great.

How does one determine the PSI of back pressure to effectively change the function of the EGR valve?

At what RPMs does the EGR actually work?

Gnarls.

[andykrow [OP]]

Ugh, baffle in place and egr still doesn't want to make the car stumble. I was sucking on the vacuum to make it do this. If I went at it really really hard it sort of slowed down the idle. Idk. Frustration... does the car need to be fully warmed up for this to work?

Not sure I should try emissions again until the egr test makes the car want to die, like the fsm says.

I should note I am using 7/64 hose instead of 3mm. It is a tiny bit smaller. Would that matter?

[emsvitil]

More backpressure doesn't affect the mixture.

It affects the EGR and modulator.     More exhaust in the intake = less NOx.

Look at the modulator and EGR and hoses in Snowtoy's post.


When the bottom of the 'T' is closed,  full available vacuum is applied to the EGR  (if the BVSV is working correctly,   BVSV is so EGR doesn't work when cold,  you can bypass as smog test is for warm conditions)

Backpressure at the bottom of the modulator and vacuum in the middle will close the bottom of the 'T'

But (this is from memory)  the middle chamber also has a controlled vacuum leak.   So if there's low backpressure and not much vacuum the bottom of the 'T' is never (or rarely) closed.    So you never get much vacuum to the EGR valve to open it up.

Toyota designed the system for the stock exhaust and muffler.     Any changes to the exhaust and you've messed up Toyota's calibration.

The plate I made was just a educated guess and it worked................