400E strange hesitation/acceleration problem PLEASE HELP
 

Hello all. After do much searching, I was unable to locate anything on my problem. So I will give it a shot here.

The car is a 92 400E. What it is doing is on heavy acceleration (mostly WOT), the car will start jumping, like someone is turning the ignition key on-off-on-off-on-off (vroomm..pause.....vrooomm.....pause...)very cyclical in nature. If I keep on the gas, it will eventually go away after a few seconds and start acceleration very powerfully and linear like it should.

I have tried my best to narrow down the problem and this is what I have found. The car hardly ever does it in second gear. Always in 3rd, and in 4th too at high high speeds. It always seems to occur over 4000 RPM. If I hold it in 3rd gear, at about 100, then give it gas, it will do it religiously. If I ease off the throttle then get back on it smoothly, it wont do it. Problem is always present at 100+MPH. And I might note that when it does this, the car barely accelerates.

One thing of note also, is that I think I have been noticing during hard acceleration, and I hit a bump in the road, it will send it into this weird "mode" momentarily.

Some people have suggested that I replace my Mass Air Meter. But I dont think this would cause this. Would it? I know that my wiring harness isnt in the best shape. But I dont want to go throwing parts (read: $$$$$$) at this without a method of narrowing down what it could be.

One thing I brainstormed up is could it possibly be one of the sensors on that tranny that retards the ignition during WOT shifts? Im out of ideas guys. Please advice.

-Andy

My 400E had very similar problem before, at highway speed, if I kicked down for max accerleration, the rpm wouldn't past 5000 rpm, as soon as rpm reached 5000 rpm, the rpm went into a kind of violent oscillation. ABS and cruiser control also didn't work.

I found out one of 4 10A fuses in the black computer box was shot, after checking the schematic, I found that fuse protected throttle control module and ABS module.

A 50 cents new fuse sloved these 3 problems, the computer box locates at the passenger side just behind the firewall.

carman850,

I appreciate the response. Unfortunetely, I already check all of them. I was hoping one of them would be broken. Anyways, I might play with it a little more tom. When the ASR is in limp home mode, does anyone know the % of throttle is allows the engine to get? Cause when its in limp home mode, the electronics (I think) and shut down, and u are manually moving the throttle via the cable like a normal car. I might put it into limp home and see if it still does it. Just another thought.


-Andy

Ok,

I just tested it and it DOES do it in limp home mode too. So I guess I can rule out the fluctuation is not due to the throttle butterfly moving, correct?

-Andy

UPDATE!! 1 step closer
 

Ok. I think I narrowed it down!! I took apart part of my console, so I could access the main harness plus for the transmission. I unplugged the transmission plug (behind the radio) and the car DOESNT DO IT ANYMORE :D . Not only does it not do that hesitation thing anymore, but the car goes like HELL!!!!! It feels like its 500 pounds lighter. Right when it hits 3500, its like a turbo kicks in. Very strange. Ofcourse I have no speedo, reverse lights, etc etc. Maybe I should just leave it unplugged and get a GPS to monitor speed. :eek:

My question is, what output out of the tranny is most likely causing this? There also could be a short in one of the wires going thru the gromet, since I did notice that hitting bumps aggravates this.

Someone with an knowledge of this tranny please shed some light on the subject. What are the certain sensors on it for? I know it has a ton more than my old 420SEL.

Thanks,

-Andy

forgot one thing
 

I forgot to mention that for some reason, ASR still functions normally with no speedo.

Do you have a full size pic of the one in your avatar?

Maybe, as long as your not a trooper ;)

Check in the archives for 500E. I remember that some one was struggling with a limp home problem that originated in the transmission. Other than that, I can't remember the solution.
Tom
92 500E

I had a similar problem in my 260E. I recommend checking your transmission fluid level. My fluid level was low.

It's a long shot, but it might be the issue...

update
 

Well, I cleared out all of my codes in the computer today, then drove it 30 miles. Then rechecked them. The computers spit out 4 codes:

code 8 (Ignition module): Tranny overload switch does not close

code 5(ASR): Stop Lamp switch (S9/1)

code 6(ASR): Starter lock-out/backup lamp switch (S16/3)

code 14(ASR): Closed throttle position contact switch (S29/3)



Could any of these things make the car behave like it is? The tranny switch seems like something I should target. hmm..


Anyone anyone???

Same Problem
 

I recently replaced my trans due to failure and have the same rough idle and acceleration as AMG. Prior to the new trans my car accelerated and ran smoothly. Since the new trans, my cars feels like a junker upon start. This problem usually goes away after 30 minutes of highway driving. I returned the car to the dealer and their diagnosis was engine mounts. Can this really be the source of my problem(s)?


AMG....

Since I am from Syracuse maybe I'll stop by and compare notes the next time I am in town. Whatever you do, don't take your car to Romano Motors. They claim to be experts but provided me with novice like service......

Brian:)

Brian,

Next time your in Syrause, drop me a line.

As far as Romano Motors, yes, I have had TERRIBLE experiences with them. I had my car there last August with this problem, and they never fixed it. I can honestly say that I know about 10 times as much info about mercedes than the service managers do there. I would constantly prove to them how they are wrong. They didnt like this.

I ordered a new transmission overload sensor and pray that it is going to solve my problem. I have cleared out the codes 3 seperate times, and this one constantly comes back, the last time, all by itself. Say a prayer.

Your rough idle could be the engine mounts, although, if its really rough, could be a combination of things.

-Andy

Andy,

Please let me know if the sensor fixes your problem. I am curious as to what may solve mine.

Where did you get the 2.82 diff?

Brian

ITS FIXED!!!!
 

I FIXED IT!!! YAHHHHHHHHHHHHHHHHH!!!


I put the new sensor in it today, and presto, the car runs like a dream.

I had to drop the pan to get the appropriate leverage to the sensor, and then had to run all around town to search for an O-ring, good thing my hardware store had metric ones.

I also notice that my WOT shifts are like glass. Im so happy its fixed.

-Andy

Where did you purchase the sensor from?

Brian

Brian,

I got the sensor from The Benz Bin

www.thebenzbin.com

However, by the sounds of your problem, this might not cure it. But its not expensive ($60) so its worth a shot. Have some small thick O-Rings on hand, your most likely going to rip the old one getting it off. Please dont hesitate with any question. You might want to check your codes before you order anything. see if anything comes out. If you dont know how, let me know, I can walk you thru the process. Its quite simple. Just make sure you have an analog volt meter.

good luck

-Andy

Andy,

Searched thebenzbin site and couldn't find a trans overlaod sensor. Please specify part name.... I will purchase the analog volt meter ASAP.

What did you use to get the computer sides?

BTW, picked up my car from the delaer and it still starts with sputtering idle when cold and it ceases after 20 -30 minutes of higway driving. The technician stated that I have both a defective crankshaft position sensor and a cylinder misfire in engine position #4. What do you think would be the quickest fix? I would like to learn more about my 400E and do the repairs myself....... Can the above fixes be done in my garage or would you reccomend the dealer.

Again thanks for your time,

Brian

Brian,

The sensor from the benz bin is as follows:

AT Protection Switch
J3065-106756 $60.72


From what you stated, do you mean that cylinder #4 is mis-firing, instead of position #4? I think thats what you meant. This could be cause by a number of this. It is most likely a bad wire. If thats the case, you just replace it. Not a hard job. It also could be a bad wiring harness. How is your wiring harness? Im sure your aware of that issue with these cars. Mine isnt in the best condition, but it works for now.

The crankshaft position sensor I dont believe to be bad. If it didnt work, the engine would not run. So I would rule that out, unless anyone has experienced intermittent issues with one??

How many miles are on your car? If I were you, what I would do is start from scratch. Clear out all the codes. Start it up, drive around the block, then recheck them. Chances are, something will tripped and it will spit out a code. These computers are very precise in narrowing down things. Once you get the codes we can go from there.

In the meantime, you might want to framiliarize yourself with the computer interface and the various computers. Here is a web page that I learned how to do it from. Its a great resource and a convenience and hats off to the maker of it. Its is...

http://pages.prodigy.net/jforgione/MB_S500.html

Those are for a 95 S500 but the majority is the same for our car. Your going to want to scroll through sections 2, 5, 6, 7,8. Print out the X11/4 Pin Map (round) in section 2. You will need that for reference when you pull the codes. We will only be using pin #'s 4, 6, 7, 8, and 17. Does your car have ASR? When you buy an analog volt meter...pick up a few short wires with alligator clips on them. They will make things alot easier in the future. And get something that will fit into those metal pinouts on the round connecter, like a metal pick or something small. I dont know if the volt meters ones will fit, they are usually too thick. Pull the cap off the computer box and check it out for yourself and you will see what im saying. They are quite small. In case you dont know where this port is, its where the battery is supposed to be, on the passenger side firewall. Its a big black box with a round plug on top that you can unsrew, kinda like a radiator cap.


Let me know when your ready and I can help ya. Good luck.

-Andy

Very Interesting
 

MCELROYB , AMG280,
I too have a 92 400E(188K mi) which exhibits a rough idle upon cold start up. Once the car warms it idle smoothly. I am NOT experiencing the problem exactly as AMG280 described(my acceleration at all speeds under all throttle positions is smooth albeit a bit stiffled) but the car continues to idle roughly despite having changed out the TBA , EGR, Plugs, Wires, Caps,(No Coils yet) Rotors,Most vacuum tubing and the Intake Manifold "O rings". It does not appear to have a vacuum leak but its really unnerving to see the car running so poorly. I'm hesitant to take it to the dealer for the reason you both mentioned...They put on a witch hunt to the tune of $85-$100 / Hr. Hell if i wanted an EXORCIST performed, I'd stop by the Church:eek: . Anyway, I read about the brake switch and the tranny neutral switch from the 500E board and am not sure they will help.
MCELROYB, your problem seems to be more like mine. Have you had any success??
AMG280 - I'm gonna go get a Analog Volt meter,read/print the article and hopefully hit paydirt soon

Albert,

Does your car only idle bad when its cold? Apparently, this is a common phenomenon with 400E's that I read about. Mine sometimes idles rough too, even surges up and down for a few seconds, but smooths out eventually. It looks like you replaced everything that it could be. Alot of 400E owners just live with it. How bad is it?

As far as the Tranny switch and the brake lamp switch, they really have nothing to do with your idle. Does your 400 have ASR? Those parts are only under a microscope if you are having ASR problems, such as ASR light coming on and/or limp home mode. They dont affect idle smoothness.

I see that you went for the "hammer" look for your car ;) , thats exactly what i want to do. Can you send me some pictures? Where did you get most of the parts, like the AMG skirt, headlights, etc.

-Andy

Yeah she misses pretty badly on start on
 

Pings too.
For pic's just click on my www . right below
AMG stuff was sourced from RennTech, but is available directly from the MB Dealer as of 1996 or so.
The Analog Volt meter. That just one with the long needle pointer that sweeps across the face like a speedometer needle right?
Where's the best place to source one? And will any ol' cheapie do?

Albert,

I checked out your mods and they look great. Can I just drop my brilliant silver W124 off with some cash and pick it up in a couple of weeks ready to roll back to MD.

I am slowly trying to mod my car as to look more aerodynamic/lowered (500E). I would also like to know where you got your parts and what should I expect to spend for the tire/wheel package? Did you roll the fenders or what?

Andy/Albert,

I am leaving the office now to pick up an analog volt meter. After receiving my E-Class Bible a few moments ago I feel much better. Andy, I even considered drving up to Syracuse to drop by while visiting my parents. Perhaps you can give me a call later this week (410-590-0912) and just walk me through a couple of steps or I will call you, whenever you prefer. Nevertheless, the next time I'm in Syracuse I owe you lunch or dinner.

Thanks again,

Brian :)

Albert,

I am going to Radio Shack to pick up my meter.

Brian

Wheels/Tires
 

The AMG AERO's I wear are out of Production/No longer available. I did see a set on EBAY a few month ago go for ~$1000. The tires in 235X45X17 run anywhere from $100(Kumho) to $270(Mich.Pilot Sport) ea, depending on the manufacturer.
As for all the 500E Parts, the Fenders,Hood,Headlights,Side valences,Fog lights, bumber cover etc. all came from the dealer(with MBCA discount of course). I did roll the fenders in the rear, but not necessary in the front due to their being 500E spec.

Brian,

I think thats very cool that your slowly modding your 400E. Im doing the same, one part at a time. I priced some wheels via the tirerack. 17 x 7.5" AMG monoblock II (C36 style) with 215-45 Bridgestone pole position SO2's (best tire period) and it came out around $1,500 with shipping. Im sure you can find a used set cheaper, but ive had bad luck in the past with slightly bent rims. I dont want to take no chances, want her to cruise nice and smooth on the freeway.

I found an AMG replica body kit from a company called NRauto for 1300 or 1500 w/the factory bosch fogs. Its high strength plastic and not fiberglass like alot fo aftermarket kits. Im thinking about getting it. I dont think I would mold the ducktail lip on the rear end though.

Albert, when you installed your rear AMG valence, where you able to attach the factory chrome strip to it? I want to keep all my chrome in tact. I also am set on getting Eibach springs with Bilstein sports and maybe a #3 or #4 pad all around. I want it to be lowered, but not "slammed". My main goal for suspension mods is to make it handle alot better and dramtically reduce body roll in hard turns. I also want to purchase 500E Ecode Euro lights. They are priced at $475 from a place called Puma. Kinda pricey, but I do alot of night driving, and from what I hear, these things kick ass.

I got my meter at radio shack for 10 bucks, it was on sale. And yes, it is the kind with the sweeping needle.

Brian, I can call you later or in the week or you can call me, doesnt matter. When are you coming to Syracuse again?

-Andy

Volt meter
 

I borrowed my neighbors voltmeter. The schematic from the reference page mentions a yellow wire for accessing the plug 19.
how do you reference plug 19 using the V.meter.

NRAuto's fiberglass kit is fine I guess. The biggest drawback is that it WILL crack/break. NO auto manufacturer uses a fiberglass nose. The paint gets sandblasted off the glass as well because it doesn't adhere as well as it does to polyeurathane. Get the OE from the dealer or RENNTECH, you'll be much happier.

Andy,

Looks like I'll be in Syracuse for the holidays. I will try do drive my W124, unless it snows then it'll be the wife's Landcruiser.

I still haven't fixed my problem. However, I did purchase the meter and await your assistance.

From reading other posts, I have found that there are numerous areas that mat need addressing. Rpley with a time to call or send via e-mail.

Brian

Brian,

Im trying to think of the best way to walk you through the process. After the first time you do it, you will be surprised at how simple it is. I see that you got your volt meter. Your gonna want another wire (probably 1 or 1.5 feet long. An alligator clip would be preferred, just would make it easier since u wont have to hold on to 10 things at once.

I take it you know where the connector is. Here is a picture of it and I highlighted the pins that you will be probing. Please note that the picture is reversed, because that is how we will be viewing it. The higher pins are on the windshield side and the lower number pins are towards the front of the car.

http://www.clarkson.edu/~prentiaa/pinout.jpg

Now, I will tell you how to test. Set your analog volt meter to measure 12 volts (most likely 15VDC).

Before pullin codes, the key has to be in position 2 (dash lights on) and not running.

You have to ground the black plug on the meter, and then put the positive (red) plug from the meter into the appropriate pin your testing (see diagram above). I usually start with 4 and work up. You now need the extra wire. Have one end of it grounded (you can use the same place that you grounded for the meter). Place the red probing pin into the #4 socket in the car. If this doesnt fit, your going to have to get a large pin or bare wire and use it as an extension.

Once in the socket, the volt meter should read approx. 12 volts. (My #17 pin reads less, this maybe normal). Once u have a steady reading (steady hands), take the second ground wire, and touch it to the red probing pin thats in the socket. Hold it there for 3-4 seconds. Note: when you touch the pin, the volt meter should read zero. After you let go, watch the volt meter. IT should start to "sweep" or "pulse" as they call it. It is up to you to count the number of pulses. If it only pulses once, this is good. It indicates no faults. If you have an error code (anything over one), write it down. To find out if there are anymore error codes in that computer, redo the above procedure until the same code pulses. If the second time u do it, its the same as the first, then that is the only code.

To erase the code, take ur second wire and ground out the red pin while still in the socket (just like above), except hold it there for 6-8 seconds. After you do this, try to read the code (re-ground it for 3 sec.) and make sure it pulses 1, to indicate its cleared out. If you have multiple codes, you have to clear them out one by one.

I suggest, to make this process alot simpler, before you do it, get a piece of paper, and write down these:

PIN # ---------------- Web Link

4-----------------------------7
6----------------------------10
7-----------------------------9
8-----------------------------8
17---------------------------5

This will make it easier after the tests to reference your codes. When I say web link, im reffering to the internal links on the this page:

http://pages.prodigy.net/jforgione/MB_S500.html

You will reference your codes here.

I think I covered everything, but if you have any questions, please post them. Good luck and let me know what you find. Make sure you dont mess with any other pins in the connector. Follow the diagram.

-Andy