does anyone own an e280 apart from me

[mr rosher]

hi everyone on the forum, i must say a big thank you, to everyone who has helped me with my ? pain of an e280 so far, so far i have changed god knows what parts and still the same problems, has anyone got an e280 1993 that they can take some pics of the vaccum pipes for me as i think i may of crossed one somewhere when doing the head gasket, i've looked at diagrams from the forum but can't figure out if i've got them wrong where the pipes lead to????? this problem started on 8th oct 2006.
rod (now slowly going mad )

 

[124coupe]

Hi, to save us reading back over old stuff, what's the problem and symptoms?

 

[mr rosher]

Hi, to save us reading back over old stuff, what's the problem and symptoms?

hi 124 coupe, start her up when cold runs nice auto choke comes off and the idle is all over the place, 600-900 for a few minutes then dies, restart her she goes 600-900 then 400-700 600-900 then dies, go for a drive its great, as soon as you stop same again, i've been getting this problem since head gasket was changed in oct, this is what i've had done and changed so far, head reskimmed decoated new valves and seals pressure tested, new harness on top end, new o.v.p.relay, new mass, new plugs, another throttle body good one, new gaskets and seals top end, new lambda, new charcoal canister, had camshaft timing reset by local dealer, been recoded by dealer and scaned comes up with code for air mass, even he's lost ?, checked and cleaned regen valve all works fine, only thing i can think of now is somewhere i've got a vaccum pipe on wrong, went to local used car sales today as there was an e280 1995 for sale so thought i would have a look but the vaccum system was different then mine, taken plugs out and she's running rich, im starting to run out of things to change and money ? so far stands me in about £1800 ?? checked with dealer as was told it may be the temperature sensor or the crankshaft sensor but he disputed it and said this would not cause the problems im getting, any thoughts,

 

[124coupe]

Hi, if the car has a code set for "Hot-Film Mass Air Sensor", then it will be using a default "limp" map which is not going to result in good running.

There is a lead from ECU to MAS that provides a regulated 5v input and also returns a voltage between 0 and 5v that represents the volume of air passing over the MAS. If this voltage is missing or "implausible", then the code is set.

The code could have been there from you either unplugging the MAS while running the engine or starting with it disconnected? This would make it a red herring!

Eliminate this one first as it fits the symptoms but shouldn't apply with your new harness and MAS.....


Do you have a blink tester (to read and reset the codes)?

 

[124coupe]

There are test specs to eliminate the air intake and coolant sensors (if you have a thermometer and a meter to measure resistance) both of these, if faulty, influence the ECU towards rich mixture.

Post if you want them.

 

[television]

There are test specs to eliminate the air intake and coolant sensors (if you have a thermometer and a meter to measure resistance) both of these, if faulty, influence the ECU towards rich mixture.

Post if you want them.

These sensors both measure the same near enough, when cold in excess of 5kΩ when hot 85c near enough 0Ω removing the wire would enrich the system in both cases.

malcolm

 

[124coupe]

Sorry but that's not true, for the E280/E320 HFM W124 here are the specs for the two NTCs:

Air Intake Temp Sensor ("IAT")

20c 6060 Ohms, 30c 3900, 40c 2600

Engine Coolant Sensor ("ECT")

20c 2500ohms, 30c 1700, 40c 1170, 50c 830, 60c 600, 70c 435, 80c 325, 90c 245, 100c 185

Within spec is the above + or -5%.

If they read colder than reality then rich running results (at colder temps the ECU lengthens the injector cycle).

I have the feedback voltage specs if you prefer to test them in situ from the ECM plug contacts assuming you can get a temp reading to compare against.