accuracy

Took my truck in second time to try to smog. First time i failed for too rich, i changed o2 sensor, replaced tps, changed exhaust gaskets to stop leak. and small other various things.

Now second time I failed for NOx of 1600ppm at 15mph, and 1800ppm at 25mph.

I was checking out egr system.

The first simple test, I suck on tube on the valve, the engine died as supposed to.

I put vacuum gauge tee'd into valve: cold i got no vacuum, and warm @ 3000-3500rpm, i get light vacuum. (somewhere between 3-5")

I then tied the R of modulator, to side of plenum (per fsm), and I do get high vacuum as I'm supposed to I believe.



The thing I am curious about is the modulator. I looked at the filter, there is a small black spot/circle on bottom. (may or may not be normal? not sure).

FSM says that If i plug off the two side ports, i should be able to blow into Q freely. Blowing when engine off has slight resistance. But That resistance is the same as when I do the same test at ~3500rpm. (fsm, says strong resistance at 3500, no resistance when engine off).



Is there a more definitive way of testing the modulator?

-Note: I have not attempted to completely remove and clean EGR yet.

truck is 86, 22re manual.

accuracy

Update: I did another test on modulator where I verified it held good vacuum and also held pressure when blowing on bottom. When I blow into the bottom, I no longer can blow through port Q, when P & R are blocked.

Thus, I want to say that means the modulator is working.


So I wanted to verify that at 3000rpm the egr system was applying pressure to bottom of Modulator. I put pressure gauge on the EGR tube where it's supposed to go to bottom of modulator. I rev'ed engine and held it, and I got no pressure reading at all. And also I redid FSM test and I could still freely blow through Q, when I block P & R @ 3000rpm.

The EGR tube is indeed warm.

Anyone have any ideas? Is my egr system working or not. It seems like its passing everything except for not putting pressure on bottom of Modulator. I'm stumped

scope103

On the 3VZE, the tube that enters the plenum can get covered in "gunk" (mostly from the PCV valve). Enough gunk could block the flow of exhaust into the plenum. I hesitate to suggest it, as I would expect a blocked tube to not be "warm". But it wouldn't hurt to pull your connection to see if you have any blockage there.

I can't see how your EGR could be working; those are REALLY high NOx numbers.

accuracy

Ah, I've been avoiding taking it off because it looks like a pain to get to the connection on the engine, and I don't have a new gasket for EGR to engine. I'll try taking a look at it again soon.
But, wouldn't sucking on the valve itself and causing engine to die indicate that the passageway is clear, since it is delivering too much extra air to intake?

And also, isn't the CAT responsible for taking out most of the NOx?

nordicwargod

Well you have verified that the bvsv vacuum switch is working and you are getting vacuum from the valve body/intake into the modulator. When you put a tee into the ERG valve and apply vacuum the engine dies, so the erg valve is opening. If there is vacuum coming from the bvsv and the intake when the engine is warm while the rpm is high and its not opening then the modulator is bad. Did you put a vacuum gauge tee'd between the modulator and erg valve? Get a vacuum reading or see if its getting vacuum? If it is then everything is working. My non professional opinion.
Now, is the erg valve partially clogged? Don't know unless you look. Since the NOx is high then the combustion temps are high. Do you have any pinging? If you do then it still sounds like the egr valve.
You were running rich since your o2 sensor died. Now that its running leaner in closed loop you may get some significant pinging if the erg valve is not opening.

accuracy

No my engine isn't pinging at all. Spark plugs look good. I've driven 60 mile trips (1way) @ 70-80mph with dirtbike & sounds healthy. I haven't owned a 22r before, and I'm not sure how gutless they are supposed to be, but i know in about 3-5th gear, after 3kish rpm, if I go WOT, I don't get any more power, but just steadily accelerates the same as if i only had half throttle. It's quite sluggish up hills and truck eventually slowly decelerates to about 55-60 if hill is very long and big (even in 4th), but that may be expected for such an old truck? Only problem is I have no cold high idle (im assuming bad IACV or cold start injector). I dont' believe it's terribly slow in acceleration though (i tested at about 13.5 sec to 60mph, with stock gearing and 29" tires and i have 4wd truck. it tops out at about 80-85mph)


about testing vacuum between EGR and Modulator, I thought that it's supposed to be Positive pressure between the two, that's why I put on a pressure gauge instead of vac gauge. I did run pipecleaner on the metal tube that goes modulator, but I didn't feel any blockage. Just came out black.

nordicwargod

Kinda sounds like your cat is clogged.
Also during high throttle or WOT as you wrote the erg valve is closed because the vacuum drops [if everything is working] So comparisons of performance may not mean anything pertaining to the erg. Since you are not pinging and the other things check out I would guess its working and something else is going on.

accuracy

Thanks for the help. I will probably get it replaced. I'm thinking when it was running really rich , it caused cat to clog

nordicwargod

Yeah, from what I have researched the cat runs real hot with it running rich and it fails quickly. One of the causes of this is the o2 sensor. If it is not working the engine will run rich in default open loop. Test or replace it. They have Bosch one's on ebay for $15 delivered.

accuracy

Yeah. I had new denso put in right after my first smog. But then... Right after I installed it, I put in 8oz of seafoam in tank, and a bit into brake booster. Not sure if I should put in a second one after that, haha. cuz I noticed it was spewing black crud out my exhaust when I was driving with the seafoam gas. hope i didn't contaminate it.