I have a 1985 240DL with around 174k miles. I replaced the MAF sensor in August with a reman from Bosch. I determined my original was bad after ohm meter testing, unplugging, and swapping out a used one (okay - but not worth keeping).

The car ran great after install. I adjusted the idle, but left everything else alone. One morning, it stumbled and stalled. I unplugged the MAF, it started, plugged it back in and it ran perfect. For about a month and a half.

It stalled again the other day. Same fix. Unplug, start the car, stop it, plug back in and it sounds great.

The last time it failed, I tried simply unplugging then re-plugging, thinking it might be the connector. It did not start.

I checked several other parts (TPS, IAC - removed and cleaned, O2 sensor). Everything else seems to be okay.

I ordered a replacement under warranty that will be here in a couple of days. It's failed twice in two days, so frequency increasing. Is there anything else that might cause this? Today, it did not sputter, just went dead. But after unplug, start, re-plug, it ran fine.

Any chance the ECU could be failing?

Thanks in advance for the help.

that's what my 10 year old reman AMM did this spring
limp home mode-stop-engine off -unplug-plug-run normal for few days
finally it wouldn't go at all
another reman AMM fixed it.

maybe just my story

gc

I think I would go with something else like a "coincidence."
That is, what you are doing is happening at the same time something else is.

It seems to be that something is getting worse so, the AMM is probably not at fault. IMHO

As far as testing with an ohmmeter, that is not reliable! R & R is the only true test!
Keep a spare around.

The wiring on these mid-eighties cars have been know to get flaky. Usually by this time some one has run some new wires.
Also make sure the fuses in the fuse panel are nice and clean. The door jam is a cold zone and moisture from your shoes and mat will condense up there behind the protective kick cover.

Next time you have this problem try jumping the fuses with a jumper wire as shown at the cleanflametrap.com site. This will run the pumps and the car will start if they are the problem. If not it might be relay. Either fuel injectors side or the pumping side.

There is a lot of other good information at the above web site, to mull over, while getting the bugs out of this car.

You should have noticed the connector on the AMM to be working properly by now, so I will leave that alone.

You asked about the ECU. That you need to take a look at and see what number and color label you have.
If it's a pink label, they are know to fail in grounding the fuel pump relay. The fuel pump itself goes or the fuel pumps fail to light off from the relay.
If it's the original pump you are approaching the end of life that is generally 200k. The in-tank pumps are less reliable mostly due to running the tank in the Orange or On empty. "O" my gosh (:-)

The relays are located under the glove box and the ECU on the right side kick panel. Both are easy to get to by removing the fiber underpinning.

In the '86 the relay went to a system relay where two relays were combined into one. It usually has a white cover unless an aftermarket was put in.

My '84 and earlier has two seperate one inch square relays. The '85 is one way or the other, that I cannot answer.
I suggest you get familiar with all these things I mentioned as you will sooner or later.
This area "Ages" just like other cars. Trick is, it's still easier to fix than most other cars and far less expensively.

IMHO
PHIL

Thanks for all the info. I did get another under warranty and will replace. I have a Programma ECU - so could be failing. Don't know about the in-tank pump. I guess I don't understand why that unplugging the MAFM, starting and re-plugging would do anything to correct any of these other issues. But, I'll certainly have a look.

Previous owner promised records, but never delivered :-(

Thanks,

hello chris,
just an observation on your ecu. i believe the 85 ecu is a bosch p/n ending in 544, LH 2.2.

these are robust and reliable. it would be rare to replace the original ecu unless one accidentally damaged it.

i replace my original 544 ecu with 554, but i kept my 544, not ever a problem with either ecu.

regards,
byron golden
86 245
92 245
94 940

25 amp fuse/holder. Fuel pump relay, corroded or loose coil wire dirty throttle body. Doubt very much its the ECU or AMM