toyturtle

Ok- so read through the relevant threads I could find, and leaning towards next step being related to the EGR...but still would appreciate thoughts- especially as I had issues with HC as well as nox

So- background. 1992 Toyota pickup, 4wd, manual, 22re 4cyl. Engine was professionally rebuilt ~7 years ago- maybe 60k miles on it since. Catalytic converter and both oxygen sensors replaced ~6 years ago.

Haven't had issues with smog since except when timing was off.


Of the most recent tests I failed the first time with the timing being off and failing both the 15mph and 25mph tests:
15mph: rpm:1598 CO2:14.3 O2:0.7 HC:139 (max is 95) CO: 0.35 NO:1337 (Max is 1058)

25mph (passed) : rpm:2516 CO2:14.7 O2: 0.4 HC:104 CO 0.33 NO
810

After fixing the idle and timing, as well as replacing plugs and a fairly worn rotor/cap, passed on the timining. (rpm warm ~750 and timing 11-14 BTDC, jumpered 5 BTDC, as it should be. (and with timing being visual, not exact, probably the fluctation going high rather then low)

So second test results again failed on 15 MPH. At both 15 and 25mph HC went down and NO went up.

15 mph (failed): RPM:1555 CO2 14.4 O2 0.7 HC: 129 (max 95) CO 0.32 NO 1454 (max 1058)
25mph (passed) RPM 2521 CO2 14.7 O2 0.3 HC 97 (max 115) CO 0.27 NO 848 (max 918)


Am I on the right path with the EGR being the next step? Does the HC going down/NO going up tell us anything? And sorry- yes- I messed up...normally (in the past at least) the report told me where the timing was off- this one didn't. And I replaced the plugs, cap and rotor before checking the timing again, so can't say for sure what the timing was 1st time (though timing had been done not to long before, but plugs had been replaced with ones gapped wrong (like .029 rather then .032...never again will I use a worn disc/slider gapper- lesson learned)

And a side note- I used one of the onlie Lambda calculators- which only used the 25mph results (the ones I passed). It showed a Lambda of 1.004 and CAT Efficiency of 36.88%.

yotajakes

as far as my understanding of the egr system, it doesn't operate at idle. only under load. if the egr was functioning at idle your engine would want to die. if it idles normally then your egr is functioning properly.

one thing I found when I failed my smog check on my new build, my o2 sensor was not flush on the mount. old gasket material left behind. allowed air to seep in. so I would thoroughly check your exhaust for leaks. then test your o2 sensors. if you want it to pass firsthand, then worry about the fix later, you can always add a bottle of isopropyl alcohol to the tank and retard the timing.

another thing to check would be the pair valve.. if you have one.

scope103

Correct: EGR doesn't operate at idle, but toyturtle's tests were not at idle.

High NOx is almost always caused by a malfunctioning EGR system. That's what it does; that's ALL it does. Run through the diagnostics: http://web.archive.org/web/201501160...ne/19egrsy.pdf

The High HC (and high NOx) could be caused by a lean condition (leak in the vacuum system, for instance). http://www.cygnusx1.net/Media/Supra/...taTech/h56.pdf But your NOx numbers are so high I would resolve the EGR first.

How high? The average passing numbers in California (I assume that's where you are) are HC: 17ppm, CO: 0.04%, and NO 53ppm. At 25mph.

Punchy

EGR works under cruise not load.
PAIR valve is suppose to only open during decal, If its stuck open it will melt the hose under load and will backflow inert gasses into the air intake, If stuck close then it does not let air flow in that burns unburnt fuel and helps exhaust velocity (a little tiny bit).

Normally HC should go higher during the cruise cycle as EGR opens to cool the burn

Dropping HC and NO at higher RPM is a sign that the CAT is heating up but its efficiency is so low to do its job, So bad CAT

You smog tech should have told you, AutoZone has a nice CAT for about $300 bolt up.

854x4

In California smog techs should never offer advise on fixing vehicles that fail emissions. All we are supposed to say is it needs to be diagnosed. This keeps us from getting sued or getting a call from the BAR.

I would start checking EGR, Vacuum leaks, Lazy O2 Sensor , Exhaust leak upstream from O2. Looking at your numbers your converter might be worn out but you need to check everything else first.

Terrys87

iTrader: (1)

I see Emission Test fails on here about once a week and might try to see if there is a thread we could create about how to fix and pass the test. Most seems to be a complete tune up, plugs, wires, rotor, cap, timing, valves, functioning EGR, hoses cleared of carbon, hoses routed correctly, a high quality catalytic converter, O2 Sensor operating correctly. Even though the pictures below are of a 22re, most applies to the 3.0 as well.

The Emission Test does seem to get problems found and fixed to where it is better then what it was before. I have to figure out as I have no machine to tell me where the problem could be as I have to test and guess what the issue is.

After it is apart, I use a drill bit, screw driver, nail, clothes hanger to get all of the carbon out. It is rock solid in places. You can put vacuum on the hose and see and hear the plunger moving and operating inside the EGR, the goldish part. I just use the vacuum of my lungs to test and hear the EGR operating for testing purposes.

While cleaning the Plenum, I got a big chunk of carbon out of it. It is at least a 1/4 inch thick. It was dirtyyyy. It was all through the Plenum and had hoses blocked.


When cleaning the EGR, this pipe will usually be plugged.


Here is one of the metal pipes that was clogged. The carbon gets hard as a rock. I use a drill bit with my fingers to help break it loose. The carbon on my finger is only half what came out of the pipe.


This is the same port that was clogged. The rest were clogged just as well. This is normal as to what you are going to find on a 150k mile or more trucks.


I worked on the EGR. Here is another picture that may look like the wrong way to do this, but the screw will strip if you use a screwdriver. Get a good firm grip, but not so hard to distort the screw.


With the screw out, get another bite on the the pipe to get it out of the EGR. Leave the carbon in the pipe at this time as it will help keep the pipe round. The carbon is hard as concrete. Slowly work back and forth to get the pipe spinning inside the EGR tube and to start breaking it free. Could take up to 10 minutes but just be patient.


I cleaned the valve to the EGR. It is marked on the sides with "Q","R","S" on the brown part as well for correct reposition. The cotton like material is easy to clean, just need to be careful with it. I also got the metal lines that connect to it cleared. One was clogged. The black top just comes straight up to remove. Will need to check the plastic lines are clear as well on it.


This line had a hard clog in it. I took a clothes hanger and air hose to it get it clear. I have fixed several code 71s just by cleaning all of the above and never had one come back yet. The tabs on the bottom willget it back into proper postition.

Terrys87

iTrader: (1)

I subscribed to this thread and if you guys that deal with California emissions can add suggestions, I can pull up more pictures or information that may help.