QuestionQUESTION: When I push my acceleration pedal to the floor my 1989 560sec seems to stumble over itself. The rpm's only reach 3000/minute. This problem only happens if I step on the pedal all the way to the floor. After giving the car a tune-up the car ran fine and I was able to get hard accelerations for only two tries getting readings of 6000 rpm's/minute. On the third try I had the same problem. I changed my spark plug wires again and the car ran fine and gave me good readings again. After about four tries the problems started again. What can make the wires go bad? Is there a regulator for the wires that may make them help.
ANSWER: Brian,
I am curious as to why you would be running the rpm to 6,000 while in a static condition, as this could certainly damage the engine, unless it is under load as in pulling the vehicle down the road.
What condition do you note out of the exhaust pipe? Is there black smoke? Is there blue smoke? Does the exhaust have a sulfur smell?
Exactly what parts were replaced during the tuneup?
Did you replace the spark plugs during the tune-up?
Rob
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QUESTION: I replaced the distributor cap, rotor, plugs and wires. There was no smoke coming from pipes and no abnormal smells. I was running my rpm's to see if the problem had stopped.
IMPORTANT TO NOTE- The second time I replaced the wires I only replaced the wires and the car ran normally. After a couple of hard accelerations the car went back to running a little rough and not being able to give hard accelerations. It seems if it were just plugs the problem would not stop by only changing the wires.
ANSWER: Have you had an emission test done. If the vehicle has high mileage or has had leaded fuel introduced, the catalytic converter my be stopped up.
The new parts may have changed the exhaust emission enough to get through the first couple of test, but as the back pressure returned the computer is readjusting the mixture.
An emission test may turn up a bad O2 sensor or a clogged converter.
Good Luck.
Let me know what you find out.
Rob
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QUESTION: I took the car over to a Mercedes dealer and they drove it and tried to diagnose it and could not come up with anything. The mechanic ruled out a clogged converter because he was able to get it up to highway speeds without problems. He suggested that I change my plugs from platinum Bosch to super Bosch. After doing this the engine ran fine and I was able to get hard accelerations for about five minutes(about the same amount of time as the other false engine remedies). When the engine stops giving hard accelerations the engine gives a deeper engine tone and it sounds like air is not being permitted to leave the engine.
Question- Could this be because a don't put the air filter compartment and connect all hoses? Maybe me leaving hoses unconnected is bringing this problem on and unmetered air is entering the engine.
PLEASE HELP!!!
AnswerBrian,
It is really important that all hoses be in place for any test of this nature. You also want to make sure that your have all vacuum hoses in place and there are no vacuum leaks.
The computer takes reading from multiple points and regulates the air fuel mixture according.
Think of you engine as an air pump.
It must have huge amounts of air going in and that same amount of air going out on each revolution.
A restricted intake can affect acceleration, as can a restricted exhaust.
On the intake side, the Mass Air Flow sensor tell the computer to send fuel to the injectors or not, to match the proper inflow ratio.
Air density is read incoming and the fuel mixture is changed to maintain an sea level equivalent.
This is why injected vehicles will perform at 9,000 feet and carburetor engines get too rich at altitude. Thin air and sea level fuel.
The URL listed below does a very good job of showing the relationship between the various components.
Copy and past it in your search window. Let me know if you if you solve the problem.
http://www.2carpros.com/first_things/why_does_my_engine_have_low_power.htm
I would try to locate an independent mechanic who specializes in Mercedes. Again, have you had an emission test run by an independent facility?
