Hi Guys,

Car is a 1987 245. Recently failed Maryland emission treadmill test with high NOx. Numbers for emissions were: HC - .8053 GPM (PASS); CO - 1.6733 GPM (PASS); and NOx - 4.6454 (FAIL - state standard is 2.8 GPM).

Any ideas on where I should look or what I should adjust or replace to get this thing passed ?

Thanks.

Mike

Anyway, here are the numbers on emissions. There have been 3 tests as follows:

First Test:

HC - 1.8468 GPM (FAIL) CO - 10.6388 GPM (PASS) NOx - 4.1271 GPM (FAIL)

Second Test - car was running cool, so put in new thermostat so car operates at normal temp.
HC - .8053 GPM (PASS) CO - 1.6733 GPM (PASS) NOx - 4.6454 GPM (FAIL)

Third Test - added new cat

HC - .2032 GPM (PASS) CO - 0.0000 GPM (PASS) NOx - 4.1760 GPM (FAIL)


Car runs fine with no misfiring, good gas mileage etc.

Here is my canned post on "NOx and Volvo/Chrysler Ignition". It might work for you as it has for several others, especially with a new cat. The first link explains the cause/effect theory. I didn't write the tech info -- just found it on a 'net search.

====================>

You may be able to pass the NOx test by plugging the vacuum line to your Volvo/Chrysler Ignition CU.
For a technical description, see my original post here and a success story here.

Other positive responses are posted in this thread
and this one.
and one more here.
Yet another one .
And another on 2/4/06.

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

Sorry.

I think I've heard that high NOx is caused by lean running??
Air leaks after the AMM will not be compensated by the AMM and it ends up running lean. Typical places are vacuum hoses, the accordion hose from AMM to the throttle body, and the intake manifold gasket. There's also a TB-to-intake manifold gasket. You certainly can check out the accordion hose and maybe replace it. Same for vacuum hoses/tubing.

There's a way to hunt for leaks with an unlit propane torch, with engine idling. I never did it. If you want to do that, better find the right safe way. Apparently the RPMs change when engine sucks in the propane, which is what makes it a nice test.
--
Sven: '89 245, IPD sways, electric rad. fan conversion, 28+ mpg - auto tranny. 850 mi/week commute. '89 245 #2 (wifemobile). '90 244 (spare, runs).

CO at 0 sounds lean to me. Probably air leaks.

The accordian probably has cracks...most do. Mine had rubbing spots where it had been rubbing and cracked through.

A good recap on the hc/nox/co relationship:

http://forums.turbobricks.com/showpost.php?p=620058&postcount=5
--
forums.turbobricks.com
Parting out '84 DL auto, many cheap parts available

About a month ago I went thru exactly what you are going thru. I am in NJ. I failed for NOx being too high. I wrote into Brickboard and it was suggested by Lucid to remove vaccuum hose/line to ignition controler and plug it up. This hose/line is under hood behind passenger side headlight. It is white colored ending in black rubber. It pushes on/pulls off metal nipple. I plugged it up with a fat nail. Anyway after doing this went back very next day to have it re-inspected. Passed with flying colors ! This trick lowered my NOx over 1000 ! I probably need a new catalytic converter but hey this trick is a hell of a lot cheaper then a new cat ! Good Luck.
--
' 86 manual sedan nearly 200,000 and ' 87 auto sedan about 120,000

Hey, its me. We met at the dyno. looks like we both failed, you should check out turbobricks.com some time.

Make sure your son takes the receipt with him because i would guess
the amount you spend on a cat will be enough to have Maryland exempt
you anyway.

If you spend more than $450 the state will waive it
anyway if you don't pass.

Karl

~200 installed if you buy a cat at fcpgroton and go to midas to have them install it. BTDT with my '87
--
forums.turbobricks.com
Parting out '84 DL auto, many cheap parts available

I failed the Maryland emissions too with my 88' 245 but I didn't read
the back of the slip that said to run the car at highway speeds for 20(?)
minutes before taking the test. Went back a week later after
cruising down I95 at 85mph for 20 mins and passed no problem! Not saying this
will work for you but the technician at the emission station was
the one to ask me if i had run the car at highway speed and of course
I had just cruised back streets all the way there!

Guess it pays to read the instructions...LOL

There are some guys that fail the NJ test on here that
block of a tube/sensor and it lowered their reading
below passing without spending the money for a new cat.

Good luck with the next test!

Karl

"...the back of the slip that said to run the car at highway speeds for 20(?)
minutes before taking the test."

When I tested my '90 244 in VA (15mph/25mph dyno), I started it up, drove about 1/2 mile to the station, and was only going to get an inspection. I got talked into the emissions test, and it passed. I was shocked!

I never thought it would pass, but the guy said, "how do you know it won't pass?" Well, obviously I didn't...
--
forums.turbobricks.com
Parting out '84 DL auto, many cheap parts available

Thanks, guys, for the comments and suggestions. One of my trusted techs here also suggested the new cat, and that is being put on today. Everything else is basically good with relatively new O2 sensor, plugs, wires, cap, rotor, air filter, oil change etc. Number 1 son will take it for emissions check this afternoon after cat install. Wil let folks know results.

Mike

My wife's '89 245 failed NOx, just slightly above the limit (I think the local Connecticut limit is a bit lower than the Maryland limit, but that's not really an issue here). The car's other emissions were well within limits and passed.

This was with a fresh tuneup already done.

I tried the "plug the vac hose to computer" fix with no improvement. Also tried dumping in large amounts of gas-line antifreeze (basically alcohol) which was another cheap fix suggested by a mechanic. No improvement that way either. A new catalytic converter got the NOx emissions well below the limit, like maybe 1/4 of what's allowed or even less.

I really didn't want to spend the money, but every tech that I asked said that was the likely solution, and it was.

The oxygen sensor is likely screwed into the driver's side of the cat converter assembly (have a look). If you want to change the cat yourself, you'll have to deal with that too. Working under the car without a shop lift I was not able to get good leverage to remove and reattach it. So be forwarned on that.
--
Sven: '89 245, IPD sways, electric rad. fan conversion, 28+ mpg - auto tranny. 850 mi/week commute. '89 245 #2 (wifemobile). '90 244 (spare, runs).

On the other hand, my 84 245 flunked consistently until I replaced the intake manifold gasket. This big air leak was accomponied by poor running when cold, so if everything else is OK, May be the CAT is bad.
I use an O2 socket to remove the sensors from the Cats. My motto is if I can't get enough leverage with my arms, use my feet. if that doesn't work get a longer breaker bar (I've been known to put pipes over the breaker bars, eventually something has got to give.....
--
744 & 745 16v 4+OD, 245 SE auto, 242Ti 4+OD, 745 8v auto (new), 245DL auto parts car