Help! Failed Emissions!

[Love My Westy]

I just took my '86 2.1 into get it inspected figuring it would pass no sweat because it only has 3400 miles on it since the last inspection a year ago. It passed on safety but failed emissions.

The results were that the HC (PPM) had risen from 48 at 15 mph and 53 at 25mph last year to 247 at 15mph and 275 at 25 mph this year.

Also the CO(%) was .12 last year at 15 mph and .13 at 25 mph last year and this year it was 2.45 at 15 mph and 5.30 at 25mph.

They said I needed to take it to a shop and have it fixed, but I'd I'd like to understand why it changed so much in so few miles, especially since they were mostly highway miles. Has the Oxygen sensor failed?, Or maybe the Catalytic Converter? I know it's about time for a tuneup and I have been thinking about ordering a tuneup kit from GoWesty of VanCafe. I haven't had any problems with the way it is running.

The first thing I am going to do is not worry about it until I get back from one last trip to So. Utah while the weather is nice. When I get back I'll do what is needed. I can change out a lot of parts rather than pay the high price that a mechanic will charge me, but I don't have the knowledge or the equipment to do the necessary adjustments so I will be taking it to the shop for that.

Any suggestions would be welcome.

Thanks, Rich in Salt Lake City

[fredn]

You need to do a tune up and then set the timing. There is a ton of unburnt fuel there, or oil. you need to find out why and where it's coming from. The answers could be timing, burnt valve, dropped lifter, bad rings, .......

[thummmper]

hc is your cat failing.
mine tested 1300 ppm at 15 mph with a 1000ppm limit. [hc] changed out the cat and lambda [oxy sensor] and retested at 563 ppm for a touchdown without doing anything else. I also had no spark when i bought it and switched brains for the solution. it got a jump that was done wrong and it damaged the spark signal of the bosch unit [brain].

[fredn]

doesn't say anything about NOX. Just HC and CO.

[Love My Westy]

The NOX was 467 at 15 mph and 328 at 25mph, higher than last year, but still well below the allowable limits.

Does this mean the Cat and the Ox Sensor are ok?

[bluebus86]

the Van cafe tester (rental unit) will help diagnos the probelms you have, it can test the O2 sendor, the throttle switch, coolant temp sendor etc.... My coolant temp sendor went intermittant, and this rental unit was able to pinpoint the problem. I found several problems with this tool, low voltage, bad O2 sendor and intermittant coolant temp sendor, after all replaced (with NO guess work) the van runs better than ever.

get the van cafe ecu tester and give it a go. You will find all sorts of little issues that will get your van running better.

[Brungeman]

check the throtle/Idle position switch. lemme see if I can describe this, with the motor off, put your ear down close to the throttle body, if you listen closely to the throttle body as you open the throttle by hand, you should hear a slight "click" of the throttle opening and coming off the idle position. if you can't hear it, take a few minutes and take the throttle body off and turn it over. You should find the switch on the bottm with a cam that operates the switch, make sure that the cam is in adjustment. If this switch isn't working clean it up as best you can, and adjust the arm of the switch to make it work, it will change the amount of fuel in the system and run rich. This process wont take money just time, and in my mind, it will pay dividends not just at the inspection station, but in your MPG's

Once that is done move onto the O2 and a new cat. You would be suprised to know how clean (relatively speaking) a van can be with all of those systems running properly! (I know this from experience)

[thummmper]

sorry--hc is the cat I was eating knachwurst at the time
HI ED!

[Love My Westy]

What I have done so far is to replace the spark plugs, wires, distributor cap and rotor. I washed the engine off before doing this and later found a wire disconnected that came from the oxygen sensor which I reconnected. I don't know if it was undone at the time of the emissions test or whether it came undone when I was pressure washing the engine.

When I move the throttle, I can hear the TPS clicking when the throttle is rotated about 1/8". I am reluctant to take the throttle body off until I get a new gasket to replace the old one.

Between the failed emissions test and cleaning the engine and replacing the plugs, wires, etc. I drove the van on an 850 mile trip to So Utah and back and it ran great. The OXS light on the dash never came on.

[Franklinstower]

[foodeater]

I had an inspection station fail my Vanagon because of the OXS light. He said it would have passed otherwise but since the light was on it failed, it came on as they were driving it into the station. He told me all this crap about ho they were going to need to replace the whole exhaust system (cat, O2 sensor, muffler, headers...etc) in order to turn the light off. I told them that I would fix it myself. I just walked over to the van pushed the button by the wheel to turn off the light, then told them I was all done, everything was fixed. They saw that the light was out and passed the van with no further mention of replacing anything.
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89 Bluestar-2.5 Subaru Powered-RIP
'84 Westy Tiico-daily driver-sold
'82 Caddy diesel-sold
'87 Vanagon Syncro-RIP
'81 diesel rabbit-sold
'82 Vanagon auto-RIP

[tencentlife]

The OXS light is a service reminder which is just switched on by a mechanical mileage counter. It has no relationship whatsoever with the function of the engine, nothing, they live at opposite ends of the van and don't even greet each other in the hallway. The sevice reminder is also a false interval, based on what manufacturers thought the service life of an O2 sensor was likely to be at the time; real experience since then has shown sensor life to be much greater in most cases, which renders the OXS light a useless warning that will only serve to scare you into thinking that something is wrong. Best approach is to go under and unplug the connector at the counter box and be done with such silliness.

Your high HC, following in such a short mileage from your good test the year before, meant that the most probable cause was no lambda regulation was occurring (cats can only reduce a small amount of excess HC so unworking cats don't result in extremely high HC counts, that can only be caused by excess fuel that is not consumed in the combustioin process; meanwhile timing and CO adjustments don't mysteriously drift off while a car is sitting, or even being driven). So when you get high HC the very first thing you go to is the O2 sensor, verify it's function before moving on to other things. Everything else is barking at the moon, until you know lambda is functioning.

Now you found that to be true, because your O2 sensor was disconnected, who knows why or how but who cares, if it's not connected the engine will run rich across the board if the AFM adjustment is anywhere near spec (base CO is set rich by default in order to proviide a richer load mixture when the WOT switch causes open-loop operation; look in the book to understand the specs).

But, for future readers to understand, and for your own future reference, the first thing you should have done if you had found the O2 sensor properly connected, was to measure the voltage output of the sensor to verify that it is producing a signal. For this you need a voltmeter, an analog style with a low voltage range like 2.5 or lower is preferred so you can watch the actual lambda correction cycling, but a digital VOM can be used just to show that there is a voltage present.

To test, pull back the little rubber boot on one side or the other of the O2 sensor conection, the place where the sensor's black wire connects to the fat green wire emerging from the engine wiring harness. Just slide the boot back to expose the connection, do not disconnect the sensor. Clip the positive lead from your VOM to the connector, connect the negative lead to a grounded point, the braided engine grounding strap is a very convenient place to clip onto. If your VOM test leads only have probe tips, two alligator-clip jumper wires can be used to go between the probe tops and the locations you want to clip on to.

Set your VOM in the low DC voltage measuring range ( a digital VOM will usually be self-ranging). Start the engine and warm it up for several minutes. On pre-'86 vans with unheated O2 sensors it may take as long as 10 minutes for the sensor to produce a signal; later vans will make voltage sooner because the sensor is being electrically heated internally. In either case holding the revs up at 2000 or so will get the sensor heated much faster. Before the sensor makes its own voltage you will probably see about 1/10 volt (100millivolt) on the line, disregard this as it is not the sensor signal yet.

As you hold the revs up and the sensor warms you will see the voltage rise, to around 1/2 volt (500 millivolt). This indicates that the sensor is working, the Nernst cell it contains is producing a voltage (the sensor cell is like a small chemical battery that generates its own voltage driven by differential oxygen pressure on the two sides of the cell, one side inside the exhaust tract and the other side exposed to ambient air). As I said, be patient, you may need to hold the revs up for as long as ten minutes before you see the voltage rise.

To see that lambda feedback is working, continue to hold the revs up at a steady throttle opening, and watch the VOM. This will only work really well with an analog VOM. The needle will fluctuate up and down, slightly above and slightly below about 500-550milivolts. The speed at which it fluctuates, and the narrowness of the spread, are good indications of the health of the sensor. A good fresh sensor will cause the needle to cross the center of the spread (i.e. the 550 millivolt point on the scale) about 4 times per second. The spread in that case will be not more than 100mv above and below the centerline.

As sensors age, their accuracy remains but they become slower; you would see fewer crossings per second, and the spread may widen because the correction response is slowed by the slower sensor feedback. But it will continue to work. When sensors fail they simply stop producing any voltage signal.

It is interesting to watch the voltage response if you let the throttle close: V will drop to zero because the injectors are cut off until the engine approaches idle speed, the the V will rise again back into the normal range, but the response time will slow because sensor temp is falling off. Rev the engine higher and you will see the V go out of range, high or low, then come back in and start fluctuating as before.

But the basic things to look for are that the sensor produces a V around 500-700mv once it is fully warmed up, that says you have a working sensor. And that at a steady mid-range rpm, the V fluctuates around a center point, that verifies that the lambda feedback between the sensor and ECU is working.
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Experience is kryptonite to doctrine.

[Love My Westy]

I took my van to Concourse Auto Werks in Salt Lake City and they checked it out for me today. It turns out that my pluging in that wire from the oxygen sensor had solved the problem. They also checked the timing and other adjustments and found everything ok except for the idle speed which is too high do to a worn throttle body which I already knew about.

On the way home I stopped by the original inspection station and had the emissions reinspected. It passed. HC was 78 at 15 mph and 109 at 25 mph, and CO was .35 at 15 mph and .35 at 25 mph.

Next time I get my van inspected, I'm going to check it over for loose wires before I take it in.

Now I can start saving for a new throttle body.

Thanks tencent for all the info on checking out the ox sensor.

[SteelB12]

My 87 failed emissions today. Failed because they said it did not have a catalytic converter. The exhaust gases were within acceptable levels. So where the hell is the CC?? Looking at the diagrams, it should be on the end of the muffler and the O2 sensor plugs into it. Well, the O2 sensor is there, but no Cat. The muffler looks too long for anything to be attached to the end. Is there an old model of muffler with the cat built in?? The only marking I can find on this can is E17 in a circle followed by 59R-015996. I looked underneath thinking maybe someone had attached a variant with the CC in a different spot. No dice. What I don't get is why remove the cat and still have the O2 sensor there.
Please refer to photos beneath:

See how long the muffler is?

Here is the O2 sensor where the Cat should be attached to the muffler:

[Spinal Tap]

Looks like the wrong muffler and no cat. The cat should bolt onto the pipe after the O2 sensor there, and the muffler bolts onto that. Yours seems to have gone AWOL at some point.

Sorry about your luck.
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'85 Westy
'74 MG-B

[SteelB12]

[purplegodzilla]

You need an O2 sensor wether you have a cat or not. The O2 acts as a close loop feedback system for the ECU. If there is no O2, the ECU will not manage the fuel correctly and will go into safe mode . Catalytic function is only to clean up the CO2.
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1995 Eurovan Camper (SOLD)
1971 Westfalia (SOLD)
1991 Westfalia (SOLD)
http://i123.photobucket.com/albums/o292/purpleGORILLA/P1020720.jpg
1985 Westfalia

[tencentlife]

[Cygnus]

have an 86 syncro, I have replaced the cat and o2 sensor, and the cap and rotor trying to get it to pass emissions - It passes high speed fine (17 out of 200) but won't pass idle emissions - they said its "beyond range" (the max allowed is 200 - I think thier ranges is at least 2k) - Haven't done plugs yet but that sounds like its so high that maybe I need to look elsewhere? Adjust the AFM? I have cleaned the Throttle body and the switch is working correctly. I turned the large screw on the throttle body all the way in and then backed out a half turn - It idles at ~900 well. So how do you folks adjust the AFM? Do you glue it back every time while you are debugging or just electrical tape it shut etc?

Any tips appreciated!

Thanks,

-Brian
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'86 Syncro Timbertech Hightop "Cygnus"

[Cygnus]

Success! A close inspection of the AFM revealed that the spring was shot on the "baffle?" inside - replaced with a spare and we passed emissions easily. Yay!

-Brian
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'86 Syncro Timbertech Hightop "Cygnus"