OverG

Hi all,

New here, thanks for the site. I have researched this enough to conclude that egr may be my problem. Daughter's 88 5000 non turbo, auto, failed NOX emissions twice, but passed HC and CO. Numbers here for latest test: HC 1.45 (limit 2.0) pass; CO 8.72 (limit 20.0) pass; NOX 4.49 (limit 4.0) fail.

First test had similar CO and HC numbers, but 4.8 Nox reading.

Second test was after oil & filter change and can of BG44K treatment(always works in my old Italian and British cars dammit!) with about 75 miles on them, 30 mins on freeway prior to test. Tune up done (not by me or during my ownership) about 10k ago.

Can someone guide me to the egr valve, its related components and its cleaning? My research points me to this as my next and most likely culprit. Car runs great, no stalling etc.

Thanks in advance!
Greg / Denver

V8QinNJ

For cars with a EGR valve I'd agree, but this isn't that kind of animal. I'd look at timing, overall engine temp...

OverG

Thanks! That jives with everything I've found in my search. Very happy to know that I am not blind nor as dumb as I thought because I could not find anything that resembles an EGR valve on this car. Haynes mentions it (big woop) and I needed to make sure I am not missing it somehow.

If I play with timing, will that affect the other two readings, CO and HC? How much / how far can I go?

Engine temp always seems fine, pretty much dead center even in hot August and Sept. Doesn't lose coolant (but is losing the more expensive Pentosin from the ps pump, another day's problem). Don't know how old the coolant is, if that's a factor. It's still bright colored, not dull and old looking, though, if that makes sense.

How about this: tank is full, and I just inquired and found out that it is full of 85 octane regular fuel. Could this be a factor? Fuel filler door says 91 octane. Should I drain and refuel with higher octane?

Thanks again!
Greg

OverG

Okay, I'm at my rope's end with this car. I have gone though all the checks to make sure the fan is working fine, replaced the thermostat and coolant to try to get engine temp as low as possible, replaced all crankcase hoses and vacuum lines, new plugs, cap, rotor and wires, oil and filter and air filter. Still fails NOX by anywhere from .02 to 1.4. Highest reading was the latest test after replacing all of the vacuum lines and crankcase hoses, which were shot once I removed them and could get a good look.

Car runs fantastic, but I now have five tests at $25 each, plus all of the above invested into a car I cannot renew. If anyone out there has a magic potion that will reduce NOX readings, I'm all ears. If anyone who does not live in an enhanced emissions area is interested and would like a very nice '88 5000S, make an offer. It is currently driveway art for me and I would love to not have to look at it anymore. All trades considered! Older vehicles preferred. Bay window bus anyone?

V8QinNJ

Have you read / done this:

http://www.sjmautotechnik.com/troubl.../10vo2sen.html

type44

Too bad the waiver is so high in Denver , its over 700 bucks. Only 150 here in Wa. I believe there was only an EGR valve on canadian models...If car is running excellent as you stated and has no vacuum leaks, my guess would be a bad o2 sensor causing it to run lean which raises combustion temps and thus nox levels, or a bad cat.

OverG

Thanks guys. I've been on the sjm site a bunch. I haven't replaced the o2 sensor or cat because the HC and CO levels are passing easily. Would either of those components those not cause it to fail in one or both of those categories?

This process is driving me Absolutely &*^king nuts. I dug through receipts and paperwork from previous years tests, and turns out the car is testing just about the same as always, but this year the limit for NOX was dropped from 6.00 to 4.00. This car has always tested just over 4.00. Is it possible it's not capable of getting better?

Our waiver threshold here for this car is $725, all must be from an 'approved' repair shop and it does not include the cost of tests and retests. I'm sure this is meant to force us to purchase newer vehicles, but I'm going the other way!

Thanks for the tips and advice, I've got a 93 Eurovan up for testing next!

chris43230

try a full tank of dry gas, passes all the time! lol

type44

A bad 3 way cat can cause nox to be high while still reducing co and hc, and while not as common a bad o2 sensor can cause a lean condition which favours reduction of co and hc but raises nox levels, running rich has the opposite effect of reducing nox but raising co and hc. If someone smarter than me knows of a way to get the cis to run slightly rich that would prob solve your problem since youre well under on co/hc.

Number68

first off, these cars do not have an EGR to the best of my knowledge..

When was your o2 sensor last changed? that can affect how hot your cats are running..

I would go ahead and pull codes, just for peace of mind. then take a trip over to sjmautotechnik.com and look up how to adjust to test your o2 sensor, and how to check your idle mixture adjustment...

how old are your injectors? sometimes the seals around them can go bad(they are air-shrouded) and cause some funky running issues. It might not hurt to replace them, I can show you my walkthrough if you want to go ahead with it.

for ****s and giggles, check your base timing as well, you can find a how to on sjm's site as well. having your timing too far advanced can cause high NOx as well...

if all these check out, it is possible you just have a bad cat, I would suggest taking it for a really spirited drive (IE WOT as much as you can get away with) to get the cat really hot. I always recommend taking a car for such a drive right before a emissions test anyway,

I used to do inspections and emissions repairs all the time BTW...