Hi,

I bought an 87 wagon with 230K on it. It passed safety, but failed emissions. Hence the post. My post is long. I have tried to anticipate your questions.

Based off of posts here, I think I know part of the problem.

On the passenger side of the engine (the engine is marked B230F), there is a shield on what I think is the exhaust manifold. This shield of metal mounts on the piece of metal that has four pipes that mount right beneath the spark plugs. The shield of metal has a crack on the seam that at the widest point (about 1 inch) is wide enough to insert the tip of several playing cards. Further, there is a hose that mounts to this shield and the hose is ripped around at least half of the circumference of the hose (where it mounts onto the shield).

Based off of posts here and my research elsewhere, I have learned the following:
The oxygen sensor analyzes the exhaust and sends adjustments to the engine. If the cracks permit ordinary air to enter the exhaust system (by sucking it in), then the oxygen sensor will send a false signal to the engine and this may cause an emissions failure.

Note that prior to the test that I ran the car for 45 minutes in highway and suburban driving. It sat for about 15 minutes at idle before the test. I have a 93 240 sedan and that temperature gauge is right at 9:00 o’clock within 10 minutes of ANY driving. In the 87 (the one that failed), the temperature gauge is at 7:30 most of the time and occasionally at 8:30 (these results were based off of several trips around town for 45 minutes or more with the temperatures at 50 to 60 degrees. I was driving in stop & go and at highway speeds).

Here are my test results. I live in Arlington, VA which is in the Washington DC metropolitan area; the standards are probably fairly stringent.

15 MPH:

HC ppm: limit=120; reading=135; result=fail
CO%: limit=.48; reading=.51; result=fail
NO ppm: limit=1565; reading=3093; result=fail
RPM=1725; result=valid (I do not know what this means)
Dilution =14.3; result=valid (I do not know what this means)

25 MPH:

HC ppm: limit=217; reading=158; result=pass
CO%: limit=.70; reading=.61; result=pass
NO ppm: limit=1522; reading=3101; result=fail
RPM=1744; result=valid (I do not know what this means)
Dilution =14.3; result=valid (I do not know what this means)

What now? Fix the cracks by replacing the parts and retest? What test or tests is/are effected by the cracks? Can I add any additives to the fuel to improve my odds?

Kreg

Paragraph 1 — no problem. Good in fact. Search on Air Box Thermostat. You don't need hot air to the air box anyhow. And when thermostart fails it defaults to hot air all the time, which is not good for the Air Mass Meter (AMM).

Paragraph 2 — true. And may be affecting your HC and CO%, which aren't extremely excessive however, in my opinion.

Paragraph 3 — sounds like running on the cool side, which is generally not a good thing for fuel efficiency or emissions. Aside from a possibly bad thermostat, try a new post on this for more ideas.

But your really gross offender is the NOx at almost twice the limit. What follows is my "canned reply" to high NOx on certain 240s...

NOx and Volvo/Chrysler Ignition
You have the Volvo/Chrysler ignition used on 240s from mid '81 thru 1988. It's been found that the V/C Ignition can contribute to High NOx, and that plugging the vacuum line to the ICU can reduce NOx levels, with little or no effect on normal operation. Note that this is NOT a guaranteed fix, but worth a try if your other numbers (and cat) are good.

This might work for you as it has for several others, depending on the condition of the cat [and that cool running, KREG]. This is not my personal theory -- I just happened to find it on a 'net search in 2004. For the technical description, see my original post here, and the resulting success story here.

Other positive responses are posted in this thread and this one,
and one more here.
Yet another one .
And another on 2/04/06.
Here's the latest, from 3/12/07.

--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.