97 E320 Running Very Rough
 

Need help
The car was in an accident, has approx 13,000.00 miles
After I start the car it runs almost smooth but when pressing on the gas pedal it starts to backfire and stalls. There was no damage to the engine.
While trying to start the car I disconnected different sensors and plugged them back, disconnected and connected the battery.
What could be the problem?
Thank you

Look to the air piping between the Air Mass Meter and the throttle assy. Sounds like you have a big air leak.

Thank you
I will look at it this afternoon

Thanks Steve

How can I tell if the Air Mass Meter is working properly?

Its pretty hard to do without some equipment. The prefered way is to look at the adaptation values and test to be sure they are not something else.

If an AMM is the cause of your problem it is pretty bad. The adaptive values should be near the max. Lower partial around 1.25 or above.

The actual output voltage can be read but a 10% skewed AMM would be about impossibly to condemn from the results and it could cause such problems.

I looked at the engine compartment, it looks like no demage anywhere to the engine but when the car is running I hear a hissing noise (like some air leak) on the right side of the engine (i can not see anything there the car does not want to run
( BEFORE IT HAD AN ACCIDENT AND I WAS TRYING WITHOUT RAD JUST COOLING PIPES CONNECTED TOGETHER)
the car has about 12000milesdoes not want to run smooth and when pressing the accelerator it back fires

please help

When I start the car it is running but rpms are going up and down from 500-700rpm.
When I press on the gas it starts to backfire and or just shuts down, I checked for air leaks but do not see any broken parts anywhere.
What are the possible couses for this one.

Thank you

Why not have the OBD scanned?

Not sure what is obd but the car is out of town and I need to tow it to the shop ,but I was hoping that I could fix it myself

This sounds silly but check to make sure your exhaust isn't plugged or bent. A flow restriction like this will allow the car to start but as soon as you increase flow the car will cut out. Worth checking if the cars been in an accident.

all exhaust looks untouchedind in perfect shape but maybe the catalityc converter is plugged from overflooding, someone told me but I did not check it yet , is it possible?

Vacuum hose is off?

I am going to put the car on the hoist today and look very closely at all vacuum connections.
Any other ideas greatly appreciated

Is it possible to check for air leaks with vacuum preasure tester and how would I do it?

I would just check the vacuum connections first and see if something came undone. That's what I thought of when you said "hissing noises". I know many on here recommend the miti-vac or something like that. I haven't used one yet, so maybe somebody will chime in.

The OBD is the Onboard Diagnostic Computer that monitors the CEC's, (computerized emission controls) of which your vehicle has many, such as the AFS, cat, evap,O2 etc,etc

If any of these have operated outside of the parameters set in the computer that would cause the vehicle to exceed 1 1/2 times the federal emissions standards it sets a hard code,ie. MIL light, if they operate outside of the range for a brief time, it stores a soft code.

However, the intent and purpose of the OBD computer is to eliminate guesswork as to why a vehicle has running problems.

All the advice given in the above posts, if indeed any of them are the problem, would be stored in the computer and would generate a code that is retrievable witha scan tool. This tells a person for instance, if the O2 sensor is malfunctioning, even for a brief period.

The DLC, ( diagnostic connector link) I believe is located on the right rear side of the firewall inside the engine compartment, it is a plastic narrow rectangular fiting about 2 inches long and 1/2 in. thick with 16 pins in it.

But, a special scan tool is needed to connect and read the codes. Some auto supply stores ( autozone) will scan the OBD for a small fee. A good web site is www.obdii.com for explanations and advice.

Good luck

Absolutely great explenation.
The diagnostic connector I belive is under the steering wheel (it looks like it).
At different times I connected and disconnected air mas flow sensor, and other sensors, also tried to start the car with the blown fuse in the black box close to right fender and after replacing it. Tried disconnecting the battery. the rearview mirror was disconnected.
Is it possible to clear the codes on my own without the special tool or it must be connected to the special tool.?

Thanks

can you please tell me if this tool will read the codes in my car and help me fix it.?
The link is here http://www.actron.com/cgi-bin/web_store.cgi?page=cp9135.htm&cart_id=8040161_12887

Whether or not you can clear the codes is kinda a trick question, one can clear certain codes after 3 drive cycles IF the problem goes away and the malfunctioning part operates correctly, other codes will not clear until after 40 drive cycles, However, on some US model vehicles, ( I am uncertain about MB) if you disconnect the battery for 5-10 minutes, the code will clear, but the monitors will be at 'not ready' for a length of time, this is only a problem if you are in an area that has OBD emissions testing like here in St Louis, the festering, oozing ulcer on the otherwise beautiful state of Missouri.

That scan tool sounds like it will work, the thing with it is that it reads onlly generic codes like P0101, MB may have some manufacturer specific codes (I am not certain about this), like P1456, some scanners are manufacturer specific.OBD was implemented in 96, so a push was made to have all vehicle manufacturers use the same codes, this is the case in newer models from about 99 on, but alot of 96-98's still will have a few Manufacturer codes.

Hope this helps, another good web site is www.necvecs.com, I think thats the right address, damn, its early and I have only had 1 cup of coffee, can't think, must have caffeine and nicotine, the breakfast of champions...


Really, a scan tool is invaluable for 96 and newer cars. Takes alot of guess work out, they will not exactly ID a problem in most cases, but will point one in the right direction.

Hi

I tried the link but it does not work, please check for the right
one for me.
Thanks

Umm, how about supporting this site by getting one of these: Ottoscan

I sounds and looks great but the other scanner is approx $100 which is about 25% of the one you are suggesting.

Thanks

www.ncvecs.colostate.edu is the correct web address. This is the national center for the study of auto emissions and they have a pretty good web site with a forum.

Thanks for the correct address

I got my codes for my 97 e320 , it just came up with one code p0100.
It looks like the mas sensor , from the list of codes , please confirm .
Is it possible to check that sensor if it is good or bad or can it be fixed somehow?

Thank you

Yes that is correct, either the unit itself or the circuit. There is a way to test voltage on it that tells if it's working or not, I believe it should read around 4-5 volts, you shoold confirm this as i am not certain.

You might begin by checkning the connection to it, clean it etc.

Good luck.

I have it removed, and would like to know if it could be tested on test bench and also if it could be repaired?

Thanks

i would like to jump in here.
i have a similar problem where car is running but wont "go" when accelerating hard. it is worse when cold. NO CHECK ENGINE LIGHT.
i have spoken to different shops and they all say no " light -no codes " .i am sure it is the mas. how do i check it?
there was mention of " soft codes" . are they still there after batt. has been disconnected?

QUESTIONS? QUESTIONS?:D

Any ideas?

DITTO:)

Can somebody help what could be the problem with code P0100

Thank you

What are the adaptation values?

stevebfl

I am not sure abut the adaptation values my friend connected a scanner and gave me a code p0100.
I read allot about the air mass failure but it is very expensive unit to purchase.

I would like to know how this could be checked with the multimeter taking redings between connecting points and also the voltages on the plug to make sure that the power is comming to the mass sensor.

Yor help greatly appreciated

To check with a multimeter you will need a wiring diagram and possibly the specific enabling data on the code in question.

Both and easily available for 20 dollars on MBs website www.startekinfo.com You will be able to print the wiring diagram plus be able to view the connector orientation to identify the proper pins. The code data is also available along with the theoretical description in the WIS section.

This is all new but I probably won't put up with as much lack of info now that it is available.

It looks like you have to become a member on that site .
I was wondering if somebody has checked different values of voltage or ohms on the unit to see if it is good or bad.

My car starts and rpm is surging 500-700 rpm but when pressing the gas the car starts to backfire and or stalls.
The code from scanner only one p0100

After the last post, I thought about writing a separate post about this issue.

I don't mean this to relect on this particular thread but let me put this in perspective.

just what kind of value should I assume people have to my advice when they won't pay 20- dollars for an answer. I have run to the shop before on saturday to get this info for people , but I won't any more. You couldn't pay me a hundred dollars to do that but I would do it for free for someone in a bind on the weekend. But I don't need to any more. Anyone who won't pay 20 dollars for the info after I tell them what they need can settle for web specualtion.

If the shoe fits its CHEAP.

It is not that I don't want to pay $20 it is that even if I got the printouts Iprobably would not know what to do with it.
That if why if I read how somebody checked it makes it very clear for me.
I compare it to reading a book with 1000 pages but all the information is on one page that I need.

Sorry for the wrong approach

i think people need to realize that not all people on this forum are trained mechanics and that sometimes just a little advise is needed. :) is that not why some of us are looking for answers here?

I answer questions where I have valuable info. I often refrain from adding the most important piece of info: there isn't a snowball chance that anything I say is going to help cause most just don't got a clue.

How would you like some guidance next week through brain surgery. The worse is the lack of respect for how complicated this can get.

I tend to go along and give all the info thats asked for even though I know most won't have a chance of using it. I have gotten some real diagnostics out of clothes pins and paper clips for those who really wish to understand. If you really wish to know I'll help. I get 20 personal email a day from people on this site expecting me to look it up for them.

It gives me the right to step on a soap box every now and then. I wouldn't even bother if it weren't for the few who really wish to know. You know how much it cost me to know.... it cost everything. I will expend any amount to know, it's always the way I have been. I don't just learn cause its cheaper than doing it some other way.

I'd rather teach em to fish than take em all to Red Lobster.

The point is that just because you can only understand a simple answer, it doesn't mean there is a simple answer. If I tell you to get a wiring diagram and thats too much for you. I need to be done. I have left more than one post where there was nothing left to add.

If what you want is that 300Es need OVP relays on Wednesdays and fuel pump relays if you didn't get a good nights sleep. I don't play that game and I leave posts that stay there after guidance.

Hi

I just purchased air mass flow meter it will be comming by mail i about a week but I am still not sure if this will fix my very rough running. If the mass will not fix it I will keep it for the future as I hear that there is many problems with those units.
Any other ideas appreciated

Thank you

This is an update on my 97 e320 (13000miles) had been in accident air bags deployed, no phisical demage to engine.

I just received my obd II scanner yesterday.
I read the following codes:

1. IAT SENSOR CIRCUIT P0110

2. MAF OR VAF CIRCUIT P0100

3. PURGE VALVE C FAULT EVAP EMMISSION CONT SYSTEM P0443

4. ENGINE COOLANT TEMP CIRCUIT P0115

After reading the codes I erased all of them, ( I think the codes came in when the engine was running and I disconected various sensor plugs) .

I read the codes again after running the car and there was only PASS no codes.

There is no check engine light comming on.

I removed the spark plugs, they were all with black charcoal on their tips.

The car runs but rpm goes from 400-700 rpm, when pressing on gas backfires and or stalls.

I did not check fuel pressure yet, only opened the valve on the fuel rail to see if there is fuel , it is comming like from water house.

Do you have any ideas what I could do next?

I appreciate your help

Any ideas?

I just replaced 3 resistor ends on the 3 ignition coils.

I replaced the air mass flow sensor.

The car is still runnig very rough

check your other 3 plug wires.
how are the coils....i was not sure how to check mine but it had some cracks and i replaced them....made a small difference.

i realized afterwards that part of my engine feeling rough was the tranny mount which was bad......it obviosly wont solve a idle or backfire problem but can confuse things.
check my old thread with an answer from arthur dalton on fuel pressures.

hope this helps:)

EVERYTHING looks like new the car has only 13k miles

I installed the spark plugs Bosch super f8dc4 today.

The car started running rough and while it was running I disconnected the plug from cam positioning sensor and also from idle stabilizer for a few seconds .

After about a minute or 2 the car started to run super smooth like a swiss watch.

It was running for about 5 minutes temperature 85C, I pressed the accelerator a bit but started very rough and from that moment on was getting worse and worse while idling and then it stalled.

I could not get it started again , it looks like it is flooded, probably tommorow will start again but rough.

The spark plugs that I removed were all black.

Thank you