I need your mechanical expertize. - PeachParts Mercedes-Benz Forum

#1 05-05-2002, 08:46 PM

The car is a 1989 260E.,
I, a Mercedes dealer and 2 independant mechanics have tried to diagnose my two problems (probably related) without success.
When cold, the engine is extremely hard to start. I need to crank it for 15 / 20 seconds before it starts. Once started, it runs fine.
When at normal operating temperature, the idle speed is very low (400 / 450RPM and sometimes stalls at traffic lights. Starts right up.
The following recently been recently done:
Valve guides/seals, full tune-up (cap, rotor,wires, spark plugs, all filters replaced (including fuel filter) OVP replaced, temperature sensor. injectors cleaned.
Any idea? Thanks
jackD

pshibly · #2 05-05-2002, 09:31 PM

Ive had the same problem. This is apparently common on the late 80's 124's. Now that youve replaced all that which i have done and the problem is still there, which for me it still is, you now need to replace the idle control valve. Ive got an apointment at the mechanics shop to have him do this. Apparently this is the next thing to replace to diagnose the problem. Another thing you could do would be to fill up with 89 octane instead of 92. Do a search in the archives for this. It is a heated debate as to whether or not lower octane will help ingition. Hope this helps

#3 05-05-2002, 09:51 PM

I have tried different octane gasoline with no result. The Mercedes dealer tried a new idle control valve on the car in their quest to find the problem. It did not make any difference.
Any other toughts??
JackD

Gilly · #4 05-05-2002, 11:07 PM

On the octane, i remember there were some issues like this on 94-95 or so E320's with the 104 engine, but not on the 103's. Good thought though. One thing that I remember mentioning just yesterday on a post, is possibly a plugged catalytic converter? Worth checking, but usually the performance will be bad also. You can just loosen the exhaust pipes from the exhaust manifold to check it. Also are you running the correct spark plugs? It's important on these to use the recommended plugs. With the low idle, this is usually some problem with the idle control system, but either of the previous 2 things I mentioned could cause that, especially the exhaust. I would recommend also to have the mechanic drive it with a fuel pressure gauge installed to see what it looks like when the problem occurs. I'm not sure if this is a single or dual pump. A dual pump system may act like this if one of the pumps is acting up. Also I remember having complaints of stalling being caused by failing fuel pump relays, they might want to think about that, especially if the pressure drops off just prior to the stall. Unsure if I recall a fuel pump relay causing a hard start though.
Gilly

pshibly · #5 05-06-2002, 12:18 AM

i replaced my whole exhaust all the way from the exhaust manifold and the problem is still persistant. i didnt put in my exhaust just because of that problem. It was time to change it. There were holes in it. Im trying to think of anything else that might be causing our problem. Out of curiosity, does anyone know what the proper idling rpm is for our car, because mine idles like its going to die and it vibrates like mad. It sits at around 450-500 rmp. never higher never lower. Then its fine when im driving. I checked my OVP and its not the faulty one. Its the good brand. I cant remember who made the faulty one. But if i have any other ideas pop into mind Ill keep you guys updated. This damn problem is affecting too many of us 260E people and no one can solve it completely. Im tired of sitting in the parking lot or at a light and everyone looks at me when it takes like 10 seconds for the engine to finally fire. And then when its sitting there its about to die and shake apart. Oh well, off to see if the motor mounts could be causing some of the vibration. Everyone keep us updated.

pshibly · #6 05-06-2002, 12:21 AM

one more symptom I forgot to mention. After I get it started and im pulling out of the parking lot, sometimes when i give it some gas i can only feel a few cylinders spark and it sputters. It feels like some of the cylinders arent firing. anyone know what im talking about?

Matt565 · #7 05-06-2002, 05:06 PM

I have a similar problem with my '88 260E. It starts right up cold, but hesitates when starting out sometimes, and if you try to start it 15-20 minutes after it has been running, it takes a few minutes to get it started. Any ideas on this one?

Matt

#8 05-06-2002, 07:06 PM

Looks like the 260E all have the same common problem. There must be someone somewhere who has a common solution.
exhaust: Checked OK. No plugged Cat converter.
OVP: tried a new one on (new model). Not the solution.
Fuel pump relay: tried a new one, Not the solution.
Octane: tried 87, 89, 91: Not the solution.
Checked ( & double-checked) for vacuum leak: No vacuum leak Manifold vacuum reading at 15in/mg at idle.
Outside the starting problem (when the engine is cold) and low idle speed, the engine runs perfectly. It has lots of power (relative), revs happily , has good gas mileage.
I can't believe that no one can find the solution to our problem.
My beloved Mercedes dealer gave me the most stupid arguement I ever heard: '' All those 260E have this problem. That,s the way Mercedes built them'' (An they charged me 7 hours of diagnostic time @ $85.00/hour to come up with this.)
Any help out there????
JackD

haasman · #9 05-06-2002, 07:40 PM

My '91 300E (175k miles) had similiar problems. I was told to run several Techron fuel injector bottles through the fuel system. I had run one about 5k miles before and felt little effect.

So I did. I ran a rich mixture through the system, twice. Cold start dramatically improved, idle rose. I think changed to copper plugs and the idle is now smooth and right at spec.

In a nutshell, it sounds to me like bad injectors, including the cold start. Considering all the other items you have done, injectors are not that great an additional investment. Make sure they are good. Test the spray pattern.

How many miles on your car?

Gilly · #10 05-06-2002, 08:05 PM

Jack:
I did have one customer who fought this problem with his 93 190 2.6, which would be similar to your 2.6L E class. He ended up replacing the injectors incl. the cold start injector and that finally fixed it. He is on mercedesshop, his title here is AKLIM, maybe you could email him and ask about all he did to fix it. Some of the work I did, other work (incl the final fix) he did himself.
Gilly

400E · #11 05-07-2002, 07:58 AM

I would agree that this sounds injector-related to me, esp. the long cranking time (e.g., injectors leaking down.)

The other thought I had was, could it possibly be a bad fuel pressure regulator? I don't know this particular engine, but on the V8s at least, many techs will start with replacing this part when they see an idle problem since they go bad with some frequency, and not too expensive. On the 119 engine, there is a new and improved part which I had to get from the dealer so if you go that route, I'd recommend doing the same (i.e., get from the dealer; some aftermarket sources still carry the OLD style).

#12 05-07-2002, 09:21 PM

After recommendations from qualified members on this forum, I had all injectors replaced today.
Guess what??????
I still have the same low idle RPM problem. (400 / 450 RPM) I don,t know yet about the hard starting problem when cold (iI'LL learn more about it tomorrow morning.
JackD
What's next?????

haasman · #13 05-07-2002, 09:35 PM

Jack,

Are you sure you have low RPM ... I am not doubting what your tach says, I am just wondering if the tach is right? Have you put your engine on a scope?

Gilly · #14 05-07-2002, 10:53 PM

Jack:
Interested in finding out if at least the hard-start is gone. Did they replace the cold start injector as well? There is a test they can do on the idle control valve to tell if it's the control module or the idle control valve. Did they replace the temp sensor for the engine management? There are a few different temp sensors, the one which affects this is the big 4-pin one towards the back of the head. There is a diagnostic chart they can follow for difficult to start cold, and also for incorrect idle. Let us know how it's starting.
Gilly

Stan Pittman · #15 05-07-2002, 11:40 PM

Have any of you thought about the fuel accumulator? From the symtoms i've read the accumulator is the culprit.