M104--poor acceleration, and cold start--related?? - PeachParts Mercedes-Benz Forum

Q-Ball · #1 01-07-2004, 05:27 PM

My 1993 300E M104, just recently starting showing some signs during start-up, when weather is below 40 degrees. Will usaully crank the first time, but reluctantly, then it seems ok....only after thorough warm-up. Once i crank her up, i typically let her warm up for about 20-30 seconds, then place in gear and proceed. Just now, outside temp 35 degrees, took 2 cranks to start up, let idle for almost a minute, then drove off. Only this time VERY poor throttle response as i left parking garage. At one point i floored it, and it did not respond quickly. Once warmed up, car ran beautifully down the highway at 80+ no sweat.
My question, are the 2 related?

OVP was just replaced. ( looked at it, and it looks loose. It sits behind batery, and is a silver box, right? It is not bolted to anything, freely moves around. possible problem?)
I don't drive it everyday.
No check engine light, ever.
Has 145K.
Very well maintained.
New harness less than 6 months (benzmac)
EGR clogged? affect? etc..

Thinking about jumping ahead and having Benzmac do a thorough 150k service.

But in the meantime i can live with it. Anyone have similar problem.

Thanks

FQ

dtf · #2 01-07-2004, 10:05 PM

When I had a problem similar to what you are describing it was because I needed new spark plugs. What color is the exhaust once it starts?

Q-Ball · #3 01-08-2004, 06:18 AM

No color to the exhaust upon start-up.
I assume it could be possible about plugs, as well as coils, and spark plug ends etc..

Has been about 15 months, 8,000 miles since last done.

FQ

dtf · #4 01-08-2004, 10:15 AM

My plugs had about 85,000 miles before they went bad. Probably not your plugs unless you're running really rich.

TROVERMAN · #5 01-08-2004, 11:56 AM

It could be this, not sure: the cold start injector. It pumps more gas into combustion chamber when cold outside (like maybe below 40 degrees!?) If this stays on, it will result in very poor throttle response, and if it is junk it may also be the cause for the slow starting. It was the problem we had on an old Volvo.

LV202 · #6 01-08-2004, 01:27 PM

There was a thread a while ago when it first got cold about this. My 104 did the same thing. The tech suggested using mid grade gas to eliminate the problem. Once it was cold my car stumbled and would almost die out on start ups. Once I switched to mid grade it never did it again. It worked like a charm for me.

kamanbosco · #7 01-17-2004, 09:32 AM

FQ:

I have a 93 300e 2.8 and have had a similar problem with starting when temp is below 20 F (it would take 2 or 3 tries to get it going). Also experienced every so often when the engine is still warming up, a lag in acceleration when gradually depressing the pedal at lower RPMs. Aside from that it runs like a charm. I've been living with this for the past couple years because it was just a minor inconvience. But this past weekend with the record cold was the first time that I wasn't able to start the car. Would crank the engine but it was just not catching.

Had it towed to my regular independent MBZ mechanic and he said that the engine was flooded and thought that the injectors may be leaking. He didn't think it was an OVP, fuel pump relay, throttle actuator, or fuel pressure regulator problem. Harness has been already upgraded. He suggested using some injector cleaner to see if it helps, but the next cold morning, he also couldn't get it started. He found a tech bulletin for this year/model that describes hard starts below 5 degress C with no fault codes. The bulletin recommends replacing the HFM-SFI module ($$$) with one with upgraded software. He said that the plugs looked like the engine has been running rich which also is described in the bulletin. Its a shame there isn't a more conclusive diagnostic available for this expensive part. I'll keep you posted if this solves the problem.

Steve

Q-Ball · #8 01-17-2004, 10:30 AM

Thanks Steve.

I would be nice if the was a better solution. but as you stated, you have lived with it, as have i. here in atlanta i obviously do not get the cold you have. But it seems when the temp drops to below 35 or so, the problem arises. Other than that, the car screems for its age, ad runs flawlesly. One solution that has minimized it for me, is put they key in the accessory position, just before start, and i leave it there for about 20 seconds. when really cold, it usually cranks the 2nd time around. I have never had to go more than 2 times.

Let me know how it goes for you, hopefully some of your record cold is on the way out.

frank

kamanbosco · #9 01-24-2004, 02:47 PM

Here's an update. I asked my mechanic to double check the OVP just to make sure it wasn't the $50 part vs. the $1300 HFI module. The OVP looked good (unfortunately), but he suggested that I could continue using the car without the new module considering that the temperature on the day I couldn't start it occurs only a few times a year (and if I had a backup car for those rare mornings). He said that when the temp drops below 20F, the module sends a signal that injects too much fuel. He said that by depressing the pedal while starting allows more air in to compensate for the over rich condition. So far this has worked everytime, right down to 12F. Anybody know if this is harmful in the long run? My mech also said that this could give him and me some time to look around for a used module. I guess this is rare because you would need to find a 2.8 that had the module replaced.

Frank: I too have been using the "leave in accessory position" for quite awhile thinking that the fuel pressure needs some time to build up. If the HFI diagnosis is correct, I suppose its not doing any good, but I've been doing it for so long, its just hard to break the habit. Personally, I think all of this would go away if I moved back to California.

Steve

canada911 · #10 01-24-2004, 03:45 PM

It could be a air leak in the manifold or the throttle body. It would explain the bad cold start and also the lost of response (and power).

'cause if there is an air leak, than air will enter the engine via that leak source instead of passing by the Air flow meter plate (AFM), and the AFM is directly responsable of the quantity of fuel injected (with the fuel distributor). That would also mean that you have the incorect fuel mixture = lack of power. Check for air leaks if the cold start injector isnt the problem, and also check your lamda value with the duty cylce to be sure that you have the correct fuel/air mixture.

Good luck!

Q-Ball · #11 02-21-2004, 09:37 PM

I am still having starting problems, and it has gotten to routine, especially if car sits for more than 2 days. Benzmac will be looking at it next week, and feels it may be a fuel injector issue, or fuel pump issue, loosing fuel pressure over time. He requires the car overnight to check thoroughly. i will give it to him soon to resolve once and for all.

i wil report back my findings.

FQ

suginami · #12 02-21-2004, 09:45 PM

I have been to MB Autowerks when I was in Atlanta on a business trip and met Benzmac (Donnie).

You will be in very good hands.

Please don't forget to post what the problem was.

Q-Ball · #13 02-21-2004, 10:38 PM

Absolutely!!

Benzmac ( Donnie ) has worked on my car for the past year, ,and everytime has been dead on with service ( harness, radiator, OVP,) . plus, they always have performance project cars in the shop. They run a great ship, and are selling Pre-owned MB's and other luxory cars now.
If anyone can diagnose it and fix it, once.....it is Benzmac.

FQ

Rocky · #14 04-23-2004, 07:26 PM

any updates?

TROVERMAN · #15 04-27-2004, 08:52 AM

In my cars owner's manual it states that the engine requires premium unleaded fuel-it is the Euro model. I understand that low grade regular fuel will cause pinging (knocking) under acceleration as well as premature catalytic wear out and less efficient running due to the high 10:1 compression. Can US models run on regular?

I know one thing...Our Range Rover, which requires premium, was not run on it before we bought it and it resulted in the purchase of 2 new cat converters. ($$$!)