Ok, my car failed the enhanced smog test in California. High NOx at 15mph (and near failing at 25mph)

1986 740GLE Wagon, B230F Engine (non-turbo), 245K Miles (new catalytic converter 5 years ago)

I’ve read many posts here and elsewhere about typical reasons for high NOx (measures below). They include:

1. clogged /partially clogged EGR Valve
2. clogged /partially clogged EGR pump
3. clogged /partially clogged EGR pump hoses
4. a vacuum /vacuum hose leak
5. injector seal leaks
6. lean fuel condition (from bad O2 sensor)
7. clogged flame trap? (NOT SURE)
8. over advanced timing (or timing is off)
9. bad catalytic converter

- Question 1. Any mistakes or ommissions?

- Question 2. Does this engine have an EGR Valve or does it use the Flame Trap? (7xx/9xx FAQs don’t address this issue directly). Found the Flame Trap on side of engine block.

- Question 3. Where is the EGR valve on a 740 B230F (non-turbo)? How do I identify it? Can't seem to find the EGR.

- Question 4. Does anybody have a photo of this on a B230F engine? how big is this item?


The Haynes book is worthless for finding anything on the B230F engine, as it seems to focus on the 760Turbo.

While I am pretty much a novice in this area of maintenance I am willing to dive in. As another poster said, “I would like to try the cheap/easiest stuff out first before I invest some serious money” Five dollars ($5) on a new Flame Trap? Sure. $200 on a new EGR Valve? Ouch!

One poster suggested uncoupling the entire intake manifold (seems the easiest with 8 nuts to remove). Another suggested removing the throttle body (??).


Here are my test numbers:

15Mph (1769 RPM)
NOX (ppm) 1276 – 1125 max (399 avg) - FAILED barely
HC (ppm) 58 – 133 max (41 avg) – pass
CO (%) 0.39 – 0.82 max (0.13 avg) – pass
%CO2 – 14.7 – pass
%O2 – 0.3 – pass

25Mph (1810 RPM)
NOx (ppm) 935 – 955 max (332 avg) - passed barely
HC (ppm) 36 – 108 max (29 avg) – pass
CO (%) 0.32 – 0.62 max (0.11 avg) – pass
%CO2 – 14.8 – pass
%O2 – 0.2 – pass

Thanks in advance for the help. Hope this wasn’t an over-abundance of info.

Damien


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Similar posts:

[Great photos of all engines except mine. All non 740, non B230F engines]

EGR vs. Flame Trap; High NOX at emission test 200
http://www.brickboard.com/RWD/index.htm?id=704114

I Don’t Have an EGR (excessive NOx emissions -- no EGR 200 1992)
http://www.brickboard.com/RWD/index.htm?id=764876

4cyl EGR questions 200 1991
http://www.brickboard.com/RWD/index.htm?id=343012

EGR - Cleaning and removal instructions
http://www.volvospeed.com/Repair/egr.htm

VolvoClub & Brickboard FAQs posted the same EGR VALVE Service Requirements
http://brickboard.com/FAQ/700-900/EngineSensors.htm#EGRValve

Great Photo for ’92 240
http://www.brickboard.com/RWD/?id=620989