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i had my car inspected 4 times and i tried a number of things to pass. i passed the 4th time. here in texas, you pay for 1 test and if you fail you have a 2nd try for free within 2 weeks. the 2nd time, i failed but the computer crashed, no official printout, and i got a 2nd try for free and i failed again.
here are my emission results for 3 of the 4 tries and what i did to pass.
1 16 dec 2005 (p=pass, f=fail) failed emission
high speed low speed
std reading | std reading
HC ppm p 162 96 | 167 128
CO % p 1.04 .59 | .94 .63
NOx ppm f 1163 1746 | 1273 2161
what i attempted to fix high nox:
1) replaced dist w/ new rebuilt on my shelf & guessed at timing--no timing light
2) checked flametrap --good
3) checked amm term 2 & 6 readings, good
4) checked plastic air ducts to amm & tb, no cracks, holes--good
5) checked dipstick gasket, seems tight enough, but put extra oring on.
6) switched dipstick from my 92 245 to my 86 245
7) checked electrical connections & grounds in engine bay, all good
8) spliced vac from tb to charcoal cannister with supple vac hose.
9) replaced vac check valve from intake man to engine compartment
10) checked valve cover--no oil leaks, no air leaks
2) 25 dec 2005 test failed but no printout so i get a second free try.
how to cut nox again:
1) new spark plugs, dist cap & rotor, air filter
2) checked injectors, readings ok per bentley
3) cleaned amm filament very carefully with carb spray, resistance in range
4) iac cleaned w/ new iac hose to manifold, iac resistance in range
5) o2 sensor heater checked per bentley, good
6) o2 checked, in range per bentley
7) injector resistance, good
8) change ecu w/ spare, no change, both ecu's good (544 & 554)
9) muffler no apparent leaks --checked up & down exhaust
10) change amm resistance from 800 ohms to about 300 ohms
11) did not change oil
12) checked for loose things in cat. nothing loose, no sulphur smell.
13) checked for exhaust manifold leaks
14) checked for intake, injector leaks with propane test-all seemed ok
and tightened intake man bolts to about 15 ft/lbs torque.
26 dec 2005 tested again --results: failed
score:
high speed low speed
std reading | std reading
HC ppm p 162 96 | 167 121
CO % p 1.04 .64 | .94 .59
NOx ppm f 1163 1388 | 1273 1991
Now, I'm getting worried, what to replace? o2, cat? dump the car?
again more work:
*1) new intake manifold gasket from shelf--noticeably oily, poor condition
2) new oil breather, o-ring gasket
3) new water temp sensor to ecu, old sensor still in resistance range--now have spare.
4) put rebuilt 70 amp alternator back on, better charging than old volvo 80 amp.
5) replaced brake booster check valve
6) bought timing light, tach & dwell from ebay,
set timing about 9.5 deg BTDC
set dwell within 20-70 deg
tach about 740 rpms, good enough
*7) muffler shop checked hairline fractures in exhaust pipe--not a problem, but found a hole in pipe on top of pipe where you can't see it, but leaking exhaust deflected flame--patched up.
31 jan 2006, another test, dramatic results
a) waited for cold day in jan to test but warm jan
b) last day before inspection expires.
**1) plugged ignition vac hose to manifold
2) high octane gas
3) cool morning, 45-50 deg ambient temp
high speed low speed
std reading last | std reading last time
HC ppm p 162 18 (96) | 167 47 (128)
CO % p 1.04 .17 (.59) | .94 .46 (.63)
NOx ppm p 1163 380 (1746) | 1273 827 (2161)
Qualitative Conclusions:
1) intake manifold probably a major leak, but probably had few earlier other small air leaks, but i checked manifold leakage with propane test earlier and didn't notice a difference in rpms.
2) plugging ignition vac hose probably highly effective.
3) followed brickboard advice to the letter:
a) if cat not rattling or plugged, don't replace.
b) o2 sensor only had about 40k miles, most likely still good, don't replace.
4) a combination of things helped, not just one single item, but i was able to eliminate possible problems and found new ones. injectors, cat, o2 sensor were all good, so was probably the plugs cap, rotor, but last 3 replaced (cheap)
5) intake manifold definitely toast, probably original.
Can probably pass Cal specs!!
My car's birth: Feb 1986, what a birthday present, happy 20 years & to 20 more. I'm now homing in on a 300k mile badge, please no wrecks.
Hope this helps those who have Nox problems and to give ideas where to start and save headaches & money. these were my problems and solutions.
thanks bb & members for sage advice.
byron golden
86 245
92 245
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"5) intake manifold definitely toast, probably original."
What leads you to blame the intake manifold? What could go wrong? New gasket may have helped—but IMO, plugging the ICU vacuum is what dropped the NOx from 1388 to 380 (which is consistent with other reports).
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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hello Bruce,
i took photos of the intake manifold, soaked in oil all the way through, from the inside intake ports edge to the other edge. i couldn't get the propane below the int/man to some ports to test for any leakage. i didn't hook up a rubber hose.
i've read that others replaced the intake manifold, replaced injector o-rings, etc and passed, if i recall, without unplugging the ignition vac.
I did a number of things. but probably neither high octane nor a moderately cool, dry morning contributed to lowering the nox.
wihout isolating it, i can't be sure which contributed the most to lowering the nox.
what about the leak in my muffler pipe? just a thought.
i poured through the archives, but i haven't seen that many posts showing an avg drop in nox produced only by plugging up the ignition vac line. i think you wrote one could expect an avg drop of 400 ppm with an old cat and 700 w/ a new cat. my drop was closer to 1000 ppm drop with an old cat.
can't say for sure for my test, unless somebody can test it.
there may be a high correlation, but no one has tested for cause and effect.
regards,
byron
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2) plugging ignition vac hose probably highly effective.
Byron,
I'm going to count that as another NOx reduction success since I started posting on it some time ago.
For those interested in the technical background, the original post is here.
and a success story here.
Other positive responses are posted in this thread
and this one, and one more here.
P,S. I wish you'd included car YEAR on the Subject line like I did here), since I'm interested in V/C Ignition and NOx (only on '82-'88), and had to search it out at the bottom. IMO, it's helpful to post the YEAR initially, so it carries down thru the thread.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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Lucid,
I'm another success story.
Last year, '82 K-jet w/Chysler ignition failed at about 200k for high NOx in urban Virginia. Sat idle for some months, until I read your suggestion. With the line plugged, it passed easily.
thanks,
--
jds
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Hello Bruce,
yes, i covered your post a number of times and followed the threads. a number of success stories convinced me to make sure that all of the bases were covered. i may have passed without plugging the vac, though, but i'm glad i didn't have to find out.
i think i would have passed fine, but the numbers probably dropped even more after the plug.
about the year, yes, you're right about convenience. i was getting tired and reading off what i wrote in my repair notebook. i did include keywords in the 2nd post i wrote.
regards,
byron
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I had a similiar expierence a couple of years ago. My best estimation of the problem was a bad intake gasket. It was leaking from the bottom so it was tough to find while on the car. I had also picked up a complete low mileage intake inectors and all from the junk yard without a cold start injector and swapped it in. The orginal cold start injector was leaking. I also changed injector seals.
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Egads Byron! With all that rain dance it's no wonder the forecast sez lotsa rain!
Took my 1988 244 in earlier this month. I was worried because I believe it's running a tad rich and the B-Board says rich = burns out cat.
Passed way far low. Where the NOX max is 1273, my score was 11.
Next to inspect is 1986 you saw at the yard. I took it in, and as they drove it for brake check, I saw that the PS tail light was not lit at all. That's a flunk, as is water in a headlight, so I took it home. Right now we have 3 drivers for 2 people, so the 1986 is off line awaiting repairs.
Last time I did a cat job, the one that came off was a straight pipe. No way to tell without pulling it off, so...
Good post, someday we'll all need some of that.
You and clamster pick a place and we'll do a chinwag over coffee, then descend on some unsuspecting junkyard.
Regards,
Bob
:>)
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Wow Bob. I would love to see a NOX reading that low. How was CO and HC? I mean you passed, but were either of them elevated? Get enough of us together and no salvage yard will be save.
Charles Armstrong
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That is pretty good values, Bob.
Charles, I've got a good junkyard in stafford area. I think Bob has one he likes too.
regards,
byron
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Pick a place along the W Sam Houston Tollway, south of Westheimer, and we'll get together. I'm out near Cypress, and the toll road is a must-use option.
Last trip to see bcg and prowl a junkyard, the drive home-to-Stafford was 25 min, low traffic conditions. Now I use EZ-tag, so it will be even quicker.
Regards,
Bob
:>)
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Hi Bob, good to hear from you. we all can meet up your way if you like. i'm all for rompin in your fav j-yard.
got some volvo euro h/lights on with h/l wipers, great stuff.
regards,
byron
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I haven't had a good junkyard scramble in a long time. Mostly hit the three Pick-a-Part locations. Lost track of a number of yards, and many I used to go to won't let you in the yard anymore. Used to have really good success with a place on N. Shepard, and one on Mykawa. Shepard one is Domestic only now and I think the one on Mykawa is gone.
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Geez you went through alot. I live not too far from you, in SW Houston, and with an 87 245 I understand the problems going through the TX emissions test. When I failed high NOX a year or so ago, I did all the basic tuneup stuff, changed the O2 sensor (it was old) and replaced the cat. passed with flying colors. I learned about the Chrysler ignition vacuum trick after I replaced the cat, or I would have tried it. Probably get very low NOX now with a relatively new cat and plugging the vacuum line. I need to get my inspection this week so I'll find out. The statement about not replacing the cat unless it is rattling or plugged should be expanded. When I pulled my cat to replace it, I found nothing inside. NOTHING. Straight pipe. Which would explain why NOX was so high. Not sure how you would know that it was empty unless you pull it and once you pull it might as well replace it.
Charles Armstong
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Charles, thanks for the reply.
yep, couldn't find the problem. i went the minimalist route, until i stumbled onto the problem. which looks like the old intake manifold. my wife bought the car new before i met her, so i don't know what all she did to it before.
interesting about the cat. what i read in the archives was the cat was always breaking down and plugging up the flow--perhaps for others, the pieces were being blown out and nothing was left. luckily, my score shows i didn't need one--just more work for me.
i don't know all about the cat problems, but you're right about just pulling it and looking at it, other than it being plugged. i read that art bernstein replaced his cat and passed brilliantly, so that was my next step and would have expected to surely pass.
i didn't expect to pass this time. I already found a used cat from a donor, and i would have replaced it within two weeks for the next inspection, if i failed.
i live in sugar land. Bob (B.C.) and a few others are in town also. maybe we can try to get a volvo something or other going here.
i think my email is in bb and if not let me know, feel free to write. i think it would be great to get a volvo org going here.
i've got a few manuals you can copy if you need them.
regards,
byron
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