ON BOARD COMPUTER

[TOPPER]

HI guys new here can anyone here tell me if my 1986 mercedes 300SDL TB have a on board computer i have look and dont see a plug?


TOPPER

[Aquaticedge]

the most you have is a EGR computer. nothing that controls the electronics on your engine other then maybe the ELR

[compu_85]

OBD-2 first appeared on a few select 1995 gasser models, and is on all 1996s. Diesel's were required to have it for 1997.

Your SDL does have several diagnostic capable modules... the EDS, SRS, and automatic climate control modules can give blink codes to help you figure out why they are grumpy.

What are you attempting to do?

-J

[ForcedInduction]

Originally Posted by compu_85

Diesel's were required to have it for 1997.

1996, E300.

[compu_85]

It may have had it, but it was not required.

[ForcedInduction]

No, EVERY vehicle sold in the USA in 1996 was required to have it. There is no distinction by the EPA or SAE for gas or diesel vehicles in the OBD II specifications.

http://www.epa.gov/obd/questions.htm
This computer-based early warning system was required by the 1990 Clean Air Act (CAA) and comes standard on all MY1996 and newer light-duty cars and trucks.

[TOPPER]

Thanks guys the reason for checking was there a computer on the car trying to fine out why when driving on flat ground around 35-40 mph car run well but when when i go faster the car just slow to a craw and when going up a hill i can almost walk faster did some reading on the cause looking for the maf sensor don't think i have one on that year car i will keeping checking and i will find out what is going on with this babby. any help

Thanks again

Topper

[compu_85]

Originally Posted by ForcedInduction

No, EVERY vehicle sold in the USA in 1996 was required to have it.

Sorry FI, you are 100% wrong. Gas cars were required, diesels were not.

You might wonder why / how I know this? 1996 Passat TDIs, as originally sold, are just OBD-D, not OBD-II. There was a TSB in 1997 where many of the cars got their computers replaced with a much more powerful one (12 bit vs. 15 bit) which was OBD-II compliant, but it was not a recall and many did not have the TSB done. Some emissions check stations don't know about the exemption for 1996 diesels and would fail the cars... computer can't talk to it!

Don't believe me? Check out this picture of the emissions tag. Note it says OBD Diesel not OBD-II. (by the yellow line)



I'll try to get one of my friends to get a better picture of the emissions label later tonight.

As I said it was an optional compliance for diesels in 1996, just like gassers in 1995. It's a nice benefit for 96 E300D owners, they get to use a scan gauge.

-J

[compu_85]

Originally Posted by TOPPER

when driving on flat ground around 35-40 mph car run well but when when i go faster the car just slow to a craw{l}

The computers on your SDL don't have much to do with how much power it makes. Your first step should be to check all the small lines between the fitting on the intake manifold and the fitting on the ALDA which is on the top of the injection pump. Also replace your fuel filters if you have not already done so.

-J

[TOPPER]

cmpu85 what about a maf sensor is there one on this 1986 300 sdl t/b

Topper

[compu_85]

Your car has an airflow meter so the computer knows how much EGR to dump in. For a test you can disconnect the EGR valve, and the air re-circulation valve (the device right by the EGR on the turbo) to see if that affects the performance. Note that unhooking the EGR and ARV will make your car emissions non compliant, so this should only be done as a test

Although the computer can tell when the EGR or airflow meter are not working properly, unhooking either will not have any negative effect on performance. (or the only other thing the computer controls, idle speed)

The fuel injection pump, apart from the idle speed, is totally mechanical and self governed.

-J

[compu_85]

Originally Posted by compu_85

Sorry FI, you are 100% wrong.

Is it sad that I'm mildly amused FI hasn't come back to this thread

-J