M103 ('89 300CE) difficult starting solved - not!

[volosong]

Original thread: M103 ('89 300CE) difficult starting solved

I'm still having starting issues. Doesn't matter if the engine is cold or warm. Same symptoms in either case.

1.) Turn the key, slight press of accelerator pedal, engine engine starts, then dies almost immediately.

2.) Will stay running if I keep the RPMs at a minimum of 750 (difficult) or 1000 (a lot easier).

3.) Will die right away if I let up on the accelerator pedal.

4.) If after starting, if I "gun it" to about 4,000 RPM, it will (usually) run as expected.

5.) Engine dies often at stops, or whenever else the engine runs at idle speeds, such as when backing out of a parking space.

6.) I can be driving for an extended time at speeds, say an hour or so; then when coming to a stop, the engine will die. But only sometimes. No definite pattern, but it is happening with more frequency lately.

7.) This one is a new symptom that I noticed the other day, and is easy to replicate. I've noticed that the engine speed oscillates if I keep the accelerator at just the right place. I can watch the tachometer record the engine oscillating between about 750 RPM and 1000 RPM. Constant pattern; up, down, up, down...like a pulsing. I can watch the needle pulse up and down between the two while I'm sitting there. Each cycle takes about a second, but that is a guess, as I didn't time it with a stop watch.

Mechanic thinks it might be an oxygen sensor (or something that I can't remember the name of). Fellow I know thinks it might be the fuel injectors. After describing the symptoms, the immediately said that the injectors were the problem.

After describing the symptoms, does anyone know what's wrong with my baby? Thanks for any insight. I'm almost to the point of dumping the car and getting a Toyota, but don't really want to.

(M103 engine with somewhere around 210,000 miles on it. Can't remember if the injectors were ever replaced. Would have to check the maintenance receipts.)

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Unrelated, when did they change the forum software? I had to re-register and my original post count was lost. Now, it looks like I'm a newby because my original join date was lost. Luckily, I was able to re-register with the same uid, and all my old posts are still here, just the post count and profile didn't get transfered.

[tinypanzer]

Have you thoroughly checked for vacuum leaks? Classic symptoms of a vacuum leak.......

Could be a lot of things, but vacuum leaks is the first thing to rule out. Also, while you're poking around in the engine compartment, check the air meter plate and make sure its centered well and operating freely.

After that, if you don't find a leak (there are probably several small leaks with a vehicle that age), check fuel pressure.....

The 02 sensor is probably not the culprit since it has no function until the car is mostly warmed up.

[J.HIDALGO]

Very similar symptoms.

[mak]

i sorted my stoplight 'stalls' by resoldering the fuel pump relay . the surging idle was sorted by cleaning the air flow intake bore ; at the bottom there accumates oil and dust ,thorioughly cleaning it ant the insides of the iCV sorted all the problem.
I have replaced all the fuses with the correct brass element. no flickering needles now.
hope this will help
regards
mak
89 300se

[tinypanzer]

Those are very good suggestions....

Cleaning the intake bore of the air meter will improve throttle responsiveness and performance in general. It is truly amazing how much crud accumulates in there, especially if you have a K&N air filter. The oil from the filter seems to exacerbate the accumulation of crud. Cleaning the bore is a good thing to do periodically, problems or not.

[ajme]

Our 190e 2.6 (similar engine) had a few more miles (230,000) when a worn airflow meter potentiometer started causing similar symptoms, along with high idle and surging when coasting. I obtained a new (used) fuel distributor and airflow meter. Then the only problem was the hard starting and dying at stop signs.

Eventually, I realized that the new fuel distributor had too great a differential between the fuel pressures in the upper and lower chambers. That was cured by adjusting the new EHA with the secret screw on the back by 1/8 of a turn clockwise. Apparently, that is a tweak disclosed in the 300e owner's bible. It brings the pressure differential back into the range where the computer can control it with the EHA. Anyway, it cured the problem for our car.

Is it possible that your problem is related?

Andrew
1989 190e

[iwrock]

I replaced the Fuel Distributor, Air Meter, EHA (pick and pull) and air filter from autozoo, and it cured my high idle, stalling, wonky acceleration, etc.

[volosong]

Thank you all for your suggestions. I see my mechanic Friday morning and will bring a printout of this thread. Just checked my copy of the "E-Class Owner's Bible", and it could be one of dozens of things. (My copy of the Haynes Manual and "Mercedes W124 1985-1995 Owners Workshop Manual" were worthless. No real troubleshooting guides.)

[SD300]

Pardon my ignorance what is a EHA?

[deanyel]

EHA = http://catalog.peachparts.com/ShopByVehicle.epc?q=1989-Mercedes--benz-300ce-Fuel--Injection&yearid=1989%40%401989&makeid=63%40%40MERCEDES%2DBENZ%40%4063%40%40MERCEDES%2DBENZ%40%40X&modelid=6173%3AMBC%7C1497%3AED%7C10000013%40%40300CE&catid=240621%40%40Fuel+Injection&subcatid=240641@@E%2EH%2EA%2E+Valve&mode=PA

[04 Diesel]

What does the EHA do?

[SD300]

i see the black piece mounted on the side of the fuel distributor.
what is her function?

[Cal Learner]

Volosong, Is this the great Enrique who's stumped by your car's symptoms? I didn't think that was supposed to happen to him.

Parts of your symptoms sound familiar. My 103 lately idles and runs rough at low speed after prolonged high-speed driving. Otherwise, the motor runs great, idles great, accelerates great, only not after prolonged high-speed driving. No CEL. I've hauled out the multimeter and done some basic testing, and I haven't figured it out. So, tomorrow, it's off to my indy. Leading suspects are:
1) OVP (mine's nearly brand new, and I can't see anything obvious wrong with it, and the ABS lamp is not on and the fuse looks good)
2) EHA (Y1)
3) EZL/CIS temp sensor (B11/2)
4) IACV (Y6)
5) throttle valve switch (S29 and S29/2), and
6) airflow position sensor (B2).
While we're at it, we'll check out the coil (it's the original). I don't even want to think about the possibility that it's the KE or EZL control units. So keep us updated on what you find, and I'll do the same.

[Cal Learner]

Originally Posted by SD300

i see the black piece mounted on the side of the fuel distributor.
what is her function?

The black piece fitted on the side of the FD is the EHA, the Electrohydraulic Actuator. Its function is to control the mixture adaptation of: (1) start enrichment; (2) post-start enrichment; (3) warming-up; (4) acceleration enrichment; (5) full load enrichment; (6) decel fuel shutoff; and (7) Lambda control. Pretty much everything involving proper fuel management.

[volosong]

Originally Posted by Cal Learner

Volosong, Is this the great Enrique who's stumped by your car's symptoms? I didn't think that was supposed to happen to him.
...

Yup. Still believe in him however. He explained to me that the problem could be caused by dozens of things and that what he is doing is addressing the most common, and least expensive things first that is causing the problem. I'll go with that. Most stealerships will just replace everything, charge you a billion bucks, hopefully fix the thing, but not really know what is wrong. In my case, it is about a 70 mile drive one-way from home to his shop and as we are trying one thing at a time, it is frustrating having to go back all the time. This Wednesday, I'm dropping the car off to him and I'll tell him to just keep it, drive it a bunch in the city, take it home, until he is satisfied the problem is fixed. To his credit, he hasn't charged me anything yet for the attempts he has taken to fix the issue.