need help!!!!

[fastdragger]

I recently picked up a 1972 280se with a 4.5 in it. Car ran great for the first tank of fuel. Then one day about a mile from home i ran it up to 70 or so and when i let off throttle it started missing and sputtering.I checked the dist. and points looked fine but noticed the vacuum adv. unit was shot.I replaced that without any luck solving the problem. any ideas what could be causing this? thanks

[t walgamuth]

I would change the fuel filter, after checking to see if it is getting spark.

Or a spray of ether to see if it will run on that, which would indicate a fuel problem.

[fastdragger]

first i need to find a good source for a manual any suggestions?

[Tony H]

Try the Classic Center-they have very reasonably priced CD manuals. You probably should become acquainted with the D-Jetronic fuel injection system since it sounds like a fuel problem. Make sure all the fundamentals are met-fuel pressure, spark, etc. Reading your post on the "other" forum it sounds like it is running very rich. The diaphragm in the pressure sensor may have ruptured due to the high vacuum created by the high speed deceleration. Normally that should never cause a problem but if it were going to fail it would fail under a high stress situation. Hopefully it's something simple.
here's the Classic Center:

http://www.mbusa.com/mercedes/heritage/classic_center/overview?WT.srch=1&WT.mc_id=13009660&iq_id=13009660&utm_source=yahoo&utm_medium=cpc&utm_term=13009660-mercedes%2Bclassic%2Bcenter

Here is a good site for D-jetronic info:

http://members.rennlist.com/pbanders/

Ignore the 914 references-the systems are very similar exept for the number of cyls

Also you should sign up on EPC:

http://epc.startekinfo.com/epc/

Tony

[fastdragger]

thanks for the help tony i'll check those out

[Graham]

Originally Posted by fastdragger

first i need to find a good source for a manual any suggestions?

Try the '73 450SE/L in this link. Should be close to same engine:

http://handbook.w116.org/matrix6.htm

If ignition checks out, it could be trigger points (located at bottom of distributor. No good way of adjusting them, but perhaps they just need cleaning.

Double check all connections including grounds, temperature sensors and MPS (pressure sensor).

Manual in sections 074 and 075 has good diagnostic info on fuel injection and ignition systems.

Check timing and watch and see if centrifugal advance works and that vacuum retard works at idle.

Vacuum at idle should be at about 16"Hg (timing affects this)

Also check the TPS (Throttle position switch) and set it properly so that idle switch activates properly. By the way, the early cars did cut off the fuel when you took foot off pedal - a bit disconcerting, so I think they changed this in later models. Perhaps this "feature" is just not working properly! I posted a write up on TPS checkup elsewhere on this forum.

Fuel pressure may be a problem - maybe fuel pump or relay malfunctioning?

Good Luck - These D-Jets are a lot of fun.

[fastdragger]

thanks graham, gonna try the basics after getting manual. if that doesn't pan out start looking for a good mechanic lol