89 300TE MA emissions test failure - PeachParts Mercedes-Benz Forum

turner · #1 12-01-2003, 09:55 PM

I have a recently acquired 89 300TE with 210K on it and it failed the MA emissions test. Specifically:

HC gpm 2.31 (limit 2.00) FAIL
CO gpm 85.50 (limit 30.00) FAIL
NOx gpm 0.38 (limit 3.00) PASS
CO2 gpm 207.15 (no limit)

I am taking it to M & J Foreign Auto Repair in Rowley MA on Wed for diagnostics and repairs.

It also has a possibly related problem:

98% of the time it runs great, idles from a cold or hot start
just fine, great acceleration etc..

Occasionally I lose all power on a fresh start after a run to the store (engine warm) or at a stop sign. I've never had it happen on a cold start.

When it's from a warm start the idle is rough and I can tell it's going to do it.

If I floor it and release it sputters in the middle.

If I put into neutral I get the same power problem.

It goes away with about 30 sec of playing with the pedal.

CE light came on once while I was having the problem.
ABS light never comes on .
OVP fuses look fine, relay has a 1996 date on it.

Any thoughts/opinions are greatly appreciated!

This sounds familiar to a lot of other hesitation issues other people have posted about.

Although none of them seem to match exactly.

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John Turner
Ipswich, MA (home of the Clam Box)

csnow · #2 12-02-2003, 01:59 PM

By the numbers, it looks like it is running too rich, or you are getting an incomplete burn.

Make sure the motor is fully warmed up before testing. A nice high-speed run can make a big difference.

Also, MA inspection equipment is notoriously inaccurate. There was something in the press about his recently, but folks in the know have been talking about it for years. Apparently, some reporters did an 'undercover expose' and blew the whole emissions testing system wide open.

Firsthand, I once got a high reading on a car that was running very sweet. In disbelief, I went elsewhere, and it passed easily. A number of folks I know were snagged by bad equipment at this particular testing facility, and passed when I steered them elsewhere.

Anyways, sounds like you have some known issues, so this may not be a promising option in your case.

Best of luck.

turner · #3 12-02-2003, 07:38 PM

Yeah There was talk that they were going to suspend the emissions part but it was going to take too long, so now they are going around and retrofitting the shops one by one.

I suspect my problems are related so I don't think a good warming up would help too much, although next time I will make sure to put it through it's paces before the inspection.

I'll be sure to post the results when I get them.

turner · #4 12-03-2003, 01:20 PM

Well the verdict on this was a bad Oxygen sensor. I suppose it makes sense, since when cold, the computer will ignore the 02 settings. net cost $200.

Since I had to have the repairs done by a licensed MA emissions repair shop, this was worth it.

What kind of multimeter do I need to test emissions components? I have a standard electrical multimeter that can test resistance and voltage, but I hear I need one that can test frequency.

Is this some kind of dumbed down version of a Scope?

Recommendations? Sears sells one that includes a thermocouple
http://www.sears.com/sr/javasr/product.do?vertical=TOOL&pid=03482400000

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John Turner

MikeTangas · #5 12-03-2003, 03:34 PM

That Sears model will do the trick. Just remember to use the black lead to pin 3 on the diagnostic port and the red lead to ground. I can't recall the reason why right now, but there is a reason.

pesuazo · #6 12-03-2003, 04:55 PM

Mike, the reason is:
The duty cycle is read backwards on the meter itself (On time, instead of off time). By reversing the leads you get the desired reading.
Key On engine Off : 70%, that is the reading you want before starting the engine.
Some people freak out because they get 68.9% or 71% any number close to 70% is OK. People cannot expect a lot of accuracy from an inexpensive meter.
Hope this helps.