M119 in 1995 S500 failed SMOG

[RicardoD]

Hi guys,

Trying to help a neighbor of mine who has a 1995 S500 with the M119 engine. He just smogged the car and failed. Any pointers on where to begin?

 

[emerydc8]

My E420 failed smog last year and prior to the second test I changed the oil, the plugs, and made sure the cats were heated up by driving it for about 20 minutes at 3-4k RPM (kept it in low gear). Right before pulling into the testing bay, I held the RPM at 3000 (in neutral) to keep the temperature up. In Arizona, all 93-95 MBs get to skip the loaded test and only have to pass the idle test, due to the inability to disable the ASR. One of my E420s doesn't even have ASR, but I still tell them it does because they don't know the difference. There's also the Guaranteed to Pass (GTP) you can try at Autozone.

https://www.500eboard.com/forums/showthread.php?t=6045&p=162653&viewfull=1#post162653

 

[TerryA]

The standard method is as emery described. I take my car on the Frwy and take it up to 80mph in third gear for about 5 miles to make sure the CATs are hot before going to my smog man.

I’ve been using the same smog guy whom I trust for at least 20 years. It helps if you find a Mercedes friendly guy and stick with him. My guy will check first and tell if it will pass or not. Thereby avoiding a “CA Gross Polluter” label on the car. Which in this case is to late.

Seek out a Smog Tech that knows our cars. Do you know if they used the roller on the rear wheels? (not supposed to use the rollers it will always fail)

Ricardo, Ask for some advise from the Tech that did all the work on your engine. He more than likely uses the same Smog Tech every time.

If all else fails your neighbor needs to have a Tech look at it before he starts throwing $$$ at it.

 

[gsxr]

Hi guys,

Trying to help a neighbor of mine who has a 1995 S500 with the M119 engine. He just smogged the car and failed. Any pointers on where to begin?

Normally I'd recommend heating the cats as described above by Jon & Terry.

However, those numbers are WAY WAY high. Like, way higher than if tested with no cats at all. I suspect something major is wrong. Bad FPR? Bad MAF? Bad O2 sensor? Ignition issues? Vacuum leaks? I dunno... first step would be to check/clear codes, but I have a feeling it may need diagnostics with live data to get an idea what's going on. I'm also assuming the car is running normally otherwise - but unless you (Ricardo) have driven it, that's an unknown. What your neighbor may consider normal may not be.

Did the car pass smog last time? Was anything done to it since then?

 

[gsxr]

Ricardo, is the test in your area done under load driving on a dyno/rollers, or with the car in park?

 

[RicardoD]

Thanks guys, definitely would like to help my neighbor check clear codes. As a 1995, I wonder if this car has OBDII. I also pointed him to my the shop I trust that pulled my M119 motor for me in Soquel, CA. Circle Star Motors. Maybe my neighbor will sign up to our board. No better place for M119 engine help.

 

[gsxr]

Ricardo, the 1995 S500 is still OBD-1 (essentially identical to the E500E). A blink code reader and/or digital scanner / SDS would be needed to view & clear codes. All the numbers look too high too only be caused by failing cats. I'm curious what he ends up finding out.

 

[samiam44]

Only times I've had issue were really dirty distributor caps, and just not getting the engine/catalysts hot enough.

Independent shops in my area have the equipment (dyno) which the obd2 cars don't need.