Need advise for my 1995 s420, it's with my mechanic right now coz we cannot tell whats wrong with it. It drives really well but sometimes it's like choking then goes away. It's hard to tell coz it doesn't happen all the time. Even diagnostics doesn't show anything. All I know is that I change my old air filters with new one's (mann air filters), then I really felt like it started from there, but almost everyone told me that's not it. Pls. help me, do you think it's the plug and wires?I have change all 8 injectors already, I am sure that's not it. Mechanictold me his thinking it's thedistributor, do you think that's the problem? Any idea pls e mail me, I would appreciate any help extended. I really like the car but I spend a lot of money to it already. My wife gets mad at me for spending money on the car but I know that it is the last problem of the car to be perfect. PLS HELP THANX>

 

make sure you didnt drop something like a rag into the air filter housing have seen that before, since you said it started after you replaced the filter, maybe clogged cats?? vaccuum hose or line off ? clogged up fuel filter?? good luck!

 

Hi,
I go along with Chassis 221 as possibilities but need a bit more info on when/how it "chokes" to refine response. Blocked cat is unlikely but possibiy the best fit to the description as it sits at present.. Do you or did you have any rattle from the cats especially when cold?

Problem Definition is EVERYTHING in cases like this.

i.e. Is it a starting problem, idle problem, highway problem and when it occurs what happens. Stops, looses power, changes gear etc etc. Is it easy to restart after episode. Does it self corrects whilst you are driving or do you need to restart etc. Is the engine warm, hot or cold engine. Engine / Road speed? Does fuel tank level play a part in when problem occurs. i.e. Low fuel level?
Anything else you can add?

I do not like non standard parts since these introduce all sorts of unwanted possibilities. Just as an example maybe the airfilter collapses and then regains shape once engine stops. Very unlikely but possible. However it appears that you have been advised that the filter is not the cause.

Its the intermittancy that the key. What can initiate a problem and then correct itself. Is the loss of power total (all cylinders), just some cyliders (need a bit more throttle pedal to maintain speed otherwise OK) or a sort of stop and go (jerkiness) scenario.

Recognising the age of the vehicle and having no info on Service History I wonder whether the filter and in tank strainer are in good order? These can give symptoms similar to what I CURRENTLY UNDERSTAND you are experiencing.

However, just as a Wild Card something suggests coil to me assuming your car only has one coil. Don't have experience on your model/engine so a bit more info here would help. However, don't rush out and buy a coil yet unless you want to give your wife good cause for being cross with you! Just bear it in mind until we are out of ideas. follow a process. we haven't moved from box one yet and already you have spent a lot of money.

Problem Definition / Possibilities / Elimination i.e. Turn problem On/Off (without cost if possible) / Rework / Confirm.

Why on earth did you change ALL of the injectors!

I await your response.

Stuart.

 

Thank you for giving me ideas, I willl check into it. The only thing wrong is that it loses power a little bit warm or cold doesn't matter. NO problem with idle, starting or catalytic converter and coils. The mechanic will check my air filters, fuel filter, ditributor rotor, distributor cap and wires and plugs today and again will see from there. Thanx again guys. Any ideas just e mail me on what else could it probably be.

 

By the way, I change all injectors before coz engine light came on and diagnostics showed that my injectors are damaged.

 

Really!

What was the code that caused the CEL to come on? I can accept one injector going down but all at once. I think not.... unless you just changed them all to be sure.

You haven'y added anything further to the Problem Description...so I am unable to help any further.... and you appear to have overlooked the coil as a possibility.

Step 1 is to better DEFINE the problem. What do you mean by "sometimes loses power". Does it clear itself. If so how long does it take. Do you need to turn the ignition off. Is gearchanging affected. Does the CEL come on etc etc. What more can you add! Is it a total loss of power or just a reduction. etc etc.

Stuart

 

Went to my mechanic again and he told me throttle actuator or throttle pan or something. This thing costs a lot and he also can't guarantee it'll be gone. That's why I have to think a lot. That's what's showing when he diagnosed it. He also told me to change distributor cap and the rotor. I drove it home today and it happened again so I stopped and turned off ignition, then turned it on again, then it ran fine up to this evening it never choked. I am so desperate to tell you the truth, especially when my wife says something bout it. THANX, most probably would be selling it.

 

Hi,

Now you have advised that an ignition OFF/ON clears the problem AND the fact that the OBD points to the throttle butterfly it looks as though the throttle butterfly has got water/corrosion inside it.

This fits with your symptoms and is simple to change but like all MB parts relatively expensive.

You may be unaware but your throttle is partly connected electrically. This is so that the engine computer can modify the amount of throttle set by your foot in order to assist with meeting emmission requirements. i.e. you call for lots of throttle on a cold engine and the ECU says NO. Just part throttle . Get the idea. Of course the electronic throttle data is also used by other systems like the auto trans.

If the servo that opens the throttle butterfly (electric) is corroded the incorrect feedback message MAY be sent to the ECU and the ECU gets its memory/brain confused. A restart resets the computer....of course it could be the throttle potentiometer, the ECU, or other parts of the electronic throttle EA but I think not.

Maybe the car was going into "limp Home" mode but this would (SHOULD) have illuminated the CEL Check Engine Light.

You need to be so careful with your description of the problem which may be correct BUT you need to include as much info as possible. For instance when the loss of power occurred did max speed drop to circa 30mpf with the gearchange going strange and this condition remained till you turned off/restarted the car. IF so this is "Limp Home" mode which immediately suggests EA problems on your vintage of car.

So bottom line.

Looks like you will have to buy a new butterfly servo UNLESS you (or somebody you know) is very DIY in which case a careful strip and rebuild of the throttle servo MAY enable the corrosion etc to be removed since the system is working OK most of the time. You may just be in luck with a bit of TLC. (tender loving care). Great care is required when reassembling to ensure that the mechanical part of the throttle linkage (assuming your car is part electronic part mecvhanical...since I'm not sure what model has what system during the 1990's) is either set correctly or at least replaced EXACTLY as it is at the moment.

Stuart