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94 s420 98 s420
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Discussion Starter #1
Two days ago the car was driving superb. weather was 58 degrees and i went to refuel, the following day the temp outside dropped to 18 degrees and the car started to hesitate on acceleration. The car would not accelerate unless I gradually give it gas, once i reach 3k RPMs it seems to operate alot better then at500-2500. Could i have gotten bad fuel? iam waiting till i finish this tank and refuel from another gas station. There is also no check engine light, however iam still getting code 19 (Fuel injectors-open or short circuit or Emission control system adaptation at limit) with the blinker under the hood. I received this code before and the car ran fine, not sure if its related at all. Again the car started to hesitate after an immediate drop in outside temp and refuelling at a new sunocco gas station, any advise? Can i add injector cleaners? why isnt there a check engine light? Thanks again on any feedback.
 

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1997 S600 (sold)
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I'd suspect the air mass meter and/or its associated intake air temp. sensor.

I'm guessing that the "adaptation at its limit" code refers to fuel trim issues. When an air mass meter starts to go, the ignition computer gets the wrong signals for how much air is being taken through the intake and falsely adjusts the fuel delivery. Your air/fuel mixture gets way off and results in your poor running situation. Eventually, due to the faulty air mass meter signals, the fuel adjustments hit the limit, and the computer generates a fault code. Some have been able to salvage their air mass meters by cleaning the hot-wire or hot-film element with spray electronic contact cleaner or by rinsing well with isopropyl alcohol. You could try this first before replacing the sensor.

Brett
 

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94 s420 98 s420
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Discussion Starter #3
Thaks for your input,when I purchased this car it had a K&N filter installed. Could the oil used to lubricate the filter be the cause of such problem? also would you happen to have a diagram of where the meter is? I noticed a sensor on the inside of the air tubes but its before the filter. I was curious what this sensor was. Iam tottaly blind without a manual. Thank you once again.
 

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1997 S600 (sold)
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I think the oil could be the culprit, and so do many Boxster owners on

another forum. Although K&N disagrees:

http://www.knfilters.com/massair.htm

I believe the sensor before the air filter is a thermocouple temp sensor. That is for reading the intake air temp. You must have an earlier car. My 97 model has the temp sensor after the air filter. The air mass meter is in a housing inline with the intake after the air filter and before the throttle body. The part of the intake with the air mass meter is a single plastic part with a large electrical connector connected to it. In my car there is a single security torx screw that holds the air mass meter in the housing. You can simply unscrew this one screw and pull it out.

pcmaher's pics in his wiring harness thread show the air mass meter. The electrical connector that has all the destroyed insulation is the air mass meter connector. Look for that same connector.

I recommend a subscription to www.alldatadiy.com. Great value for US$25/year. It is essentially the W140 CD on the web. Or buy the CD for around $150 from various sources, or pirate a copy from someone for free.

Brett
 

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Discussion Starter #5
I just priced and viewed an image of the meter, god its $748 for a bosch. I will defintely clean it first. Do you think the oil from the K&n filter could have possibly contaminated the sensor? I think I over did it 2 months ago, not thinking it could leak into sensors. Iam waiting for a warm day here in north jersey to investigate further, dont have my own garage. what other sensors would trigger an emission adaption code, thanks again.
 

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1995 S600 (sold)
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Get rid of the K&N's! Quick! Sorry to hear you're having trouble. Follow Brett's advice, and carefully try to clean the inside of the Mass Air Flow (MAF) sensor using a cleaner specifically meant for sensitive electronic components. Isopropyl alcohol is good, but it doesn't dissolve all contaminants well. Some electronics cleaners come in spray cans that spray the solution out under a good deal of pressure. Be careful with the force of the spray, but it may just be what's needed to clean off any crud on the wire. I'm attaching a picture below showing the MAF, it's the part between the air filter box and the rubber intake runner. The connector is off in this photo. Brett is also correct about that sensor in front of the air filter box. It measures incoming air temperature.
 

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Discussion Starter #7
Thank you for the quick replies, K&N airfilter is coming out and will stop by radio shack tomorrow and get the presurized electrical cleaner, I will keep you posted how it goes, just waiting for a nice day to work on it. Thanks again for your professional input.
 

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Discussion Starter #8
started the car today and at first i thought my problem was gone, but once the temp rose the problem accured. I first cleaned the air intake sensor with pressurized electrical cleaner and tested the accelration, my problem was still there. I then removed the air filter housing and air filter and had a total view of the air flow meter/sensor. The inner sensors looked very clean, theres one probe that sticks out which had a metalic finish to it with no signs of oils or corrosion, right under that theres a square filament wiring that cirumfranced the meter housing, that also looked very clean. I sprayed it carefully and replaced my air filter back. I test the car and my problem was still there. I can only accelerate with a gradual press of the gas pedal. Once I floor the pedal the car will not accelerate or will stutter into accelration. Can this be an EGR valve problem? Iam leaning towards bad fuel and also remembered a similar problem on a friends car that had a cloged EGR valve Any thoughts guys of where to go next. The car seemed to be alot better when I initially started it, air intake sensor replacement? not sure at all. I also called the previous owner and he informed me he never changed the fuel filter in the 4 years he owned the car. EGR, airintake sensor, fuel filter, any thoughts? Thanks
 

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Discussion Starter #9
Pcmaher I read on one of your older posts you were considering using REDLINE SI cleaner. Have you tried it? what were the results? I Would like to add an injector cleaner not sure if i should or not. so iam asking for your past experience. Car is still running rough/jerks on acceleration. not sure where to go from here. thanks
 

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Yes, I used the Redline Injector cleaner in two tankfuls. I did not notice a difference at all. I wouldn't bother with that stuff. For the record, I also used Techron...same thing, no difference.
 

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1997 S600 (sold)
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What year and model is your car? The electronic throttle actuators (ETA) on some

models can suffer a failure related to the main potentiometer that regulates the throttle. I don't know if the symptoms of this failure are like you describe for your car, but it never hurts to be educated on these things.

Someone (myanmar maybe) posted a link in one of pcmaher's threads to a thread from Mercedesshop.com on this issue.

Also, engine wiring harness are a known issue up to MY1995. The symptoms seem like you describe, a generally rough running scenario, loss of power on acceleration, etc.

Generally, poor running is caused by bad air intake, bad fuel delivery, or bad spark. Might also be caused by bad exhaust system in terms of cats being plugged as Merc600SEC reported recently.

Specifically now (and this is stream of consciousness off the top of my head. The list is by no means comprehensive.)

bad air intake: vacuum leaks, bad egr valve which essentially creats a bad vacuum leak,

bad fuel delivery: fuel injectors and the wiring harness that powers the injectors, fuel pump, fuel filter, fuel pressure regulator, throttle actuator, throttle position sensor, fuel lines

bad spark: spark plugs, spark plug wires, ignition coils, if you have distributor ignition then distributor cap and rotor, timing advance mechanism, if you have fully electronic ignition then the engine ecu, flywheel position sensor.

That's a start. When you have ruled all these out, give us a call back. [:)]

Do you have any other information to provide? More specific details on your symptoms.

Brett
 

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Discussion Starter #12
Well here is my daily briefing, my goal for the day was to remove the EGR valve for a visual inspection. I connected a hose to it and followed the steps for testing it according to a previous post on this forum. No luck in removing it, since I didnt have the proper tools ( metric allen set). While standing under the hood reving the engine using the throttle linkage ( are you ready for this) the lower radiator hose blows out and antifreez gushes out all over. I was in disbelief, here iam trying to fix one problem and a setback with a radiator hose. hose clamp was tightened before the lip not after and the hose slid right off, greatfull it didnt happen on the highway. I tried tightning the clamp from under the hood but was hard to reach, and there was a splash guard under the engine so that was out of the question. I finally removed the towing flap on the bumper and was able to squeeze my hands in and tighten it thru there. The nearest auto store is 15 blocks away, am i risking further damage if i drive there with low antifrees? I dont want to run the pump dry and risk damaging the water pump seal. The previous owner of this car is my cousin and has receipts for the plugs, wiring harness, plug wires ( expensive) and several other expensive maintnance.
some of these items like the plugs are 22k miles ago. I will start with the cheapest first, like the fuel filter, spark plugs (check for abnormal firing),Egr cleaning and take it step by step from there. Iam due for both of these items so i may well go ahead and change them and see if it stops the hesitation. Iam also waiting for the tank to fnish so i can refuel from another station. I tell you what guys iam kinda hearbroken here, the car looks great, it handles great, I feel great getting into it and i probably would never want another car then an s class. However I had more problems with this 94 s420 then any other car i owned. Its a love and hate relationship. I will come back with any updates, thanks for the support.
 

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Discussion Starter #13
Please disregard me driving 15 blocks on low antifreez, I would have done it with some of my previous cars but not with this one. Dont want to ruin the waterpump seal.
 

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bass1175 - 3/11/2005 9:55 PM
I tell you what guys iam kinda hearbroken here, the car looks great, it handles great, I feel great getting into it and i probably would never want another car then an s class. However I had more problems with this 94 s420 then any other car i owned. Its a love and hate relationship.
bass1175, we know what you're going through. Most of us have been there, or are there right now. You said it perfectly; it can be a love / hate relationship. In fact, there is a member of this forum that uses this phrase as his logon. Don't give up. We'll do our best to help you get your baby running right. I wanted to tell you to avoid the platinum type plugs if you're going to change plugs. Stick with the regular old-fashioned electrode type, and make SURE you get the right part number for your model and year. Also, you might want to visit a filling station that can siphon the existing gas out of the car so you can fill up with fresh fuel. Keep us posted, and Hang In There!
 

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1997 S600 (sold)
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I'm sorry bass, but I laughed. Since that clamp was on wrong

that means it has been removed. Unless it came like that from the factory, but that seems unlikely. Does that indicate something in the car's history that you don't know about? Was it simply the hoses have been replaced? Was the radiator pulled for more extensive repairs? Those would be my thoughts, but it may still have no bearing on your current rough running situation.

You say the "wiring harness" has been replaced. Which one? I would still visually check your fuel injector wires. Someone, I think merc600SEC, posted pics of his bad wires several months ago. You may find them in his gallery or by searching the forum.

Brett
 

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92 500SEL to 01 E320T current 2014 lexus LS460
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I scanned your woes, (the tecnical director at the MB magazine "STAR" did not have anything good to say about K&N and the oiling of the sensor) PLEASE leave your comments that for another thread.
I suggest you check your rotors and caps. My 500 was hesitating on acceleration on occasion but would run fine after getting up to speed. They pulled of one of the caps and the contacts were green with corrosion and burning. I definately would not buy them at your local MB you will be shocked. You need get rotors, gasket, and cap there are two one each on on each side.
 

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And just a small point..
NEVER NEVER EVER use the throttle control inside the engine bay to rev the motor.. This could be the cause of your troubles.. If you have done this they could be out of sync now with the acelerator peddle..I am sure others can give you more details.. you will need to clear the codes down and re set..
 

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Discussion Starter #18
Thanks for all the help guys, mysteriosly enough after I added my antifreez today, the problem disappeared. The only difference from yesterday and today was, I sprayed electrical cleaner in my EGR valve. I figured it was quick drying and leaves no residue, so I sprayed lightly inside. I couldnt believe it but the car was unreal after, not sure if that was the fix or if it was an increase in outside air temp (not by much). It didnt hesitate at all, and the acceleration is back to normal, with much power. I wonder if spraying the EGR fixed my problem. I Will keep you guys posted if that fixed my problem or if it returns. I also added new fuel today but the problem was fixed before

Merc600 I only used the throttle under the hood after my problem occured, and thanks for the heads up.

peter what comments are you reffering to?

Love the forum, thank you all
 

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92 500SEL to 01 E320T current 2014 lexus LS460
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Sorry, someone posted the comment about K&N on the Mercedes Club Site and it started a verbal war, of the pros of K&N. I thought this link would get all clutterd up with comments. I am glad you solved the problem, and yes they warn about using the throttle linkage under the hood!
 
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