my car has suddenly gotten rather slow...
 

Hey guys. The other day, on my way to school, I noticed that my car was running very slow. I would floor it (not hitting the switch) and the car wouldn't pull out of the 2-3k rpm range. I was rather alarmed but because I had school, I just parked the car and went on with my day. On the way back, the car wasn't nearly as slow as it was in the morning, but it was still slower than usual. This has been going on for the past couple of days. I timed my car today, and its running 0-60 in the high 9s. About a second slower than the mercedes specs... It doesn't seem nearly as responsive as before, and im having to hit the floor switch in order to maintain speed up hills. This slowness has coincided with some cold weather around here (Austin) In the mornings its around 32, and by the time I get home its around 55. I had 10w40 oil put in my car a few weeks ago. (Somebody had suggested 15w40, but the guys at jiffylube, my dad had it changed, said that it was used for diesels) Does anyone know what the problem might be? I have never driven the car with this oil cold before, could it be the oil? Even when the engine/oil warms up (15+miles), the car is as sluggish as when cold. Any suggestions would be greatly appreciated.

Its not the oil unless you don't have any of it.

hehe... not to worry there, its all topped off. here is another idea, could the spark plugs be gunked? The car is making a rat-tata diesel-eske noise when you get real close to the block. You can't hear it without your head outside the engine bay. I have no idea when the plugs were last changed....

plugs could be fouled or your cat could be plugged.

if you've got an old cat, the ceramic can break loose and lodge sideways almost completely cutting off exhaust flow. i had this happen to me. it killed my performance.

Hmm... the car is a 92, and its supposed to have an aftermarket cat on it (the words of the tech to my dad, I haven't been able to gleen anything else) It does have fuel enrichment controlled by a thermostat. I had this thermostat altered with an iniline resistor in order to increase fuel enrichment to complement the r-16 resistor modification. I suppose it just got too cold and the car was dumping in too much fuel for the car's old plugs and wires to burn effectively. I connected the temp sensor back to normal, and the car seemed to chug along just fine. Ill have a better sense in the morning though, and ill keep you guys posted.

doubt thats it,,,, i run my resisted temp sensor in negitive degree weather. seems faster in the cold to me (air is more dense). I would recommend checking the ignition system or maybe replacing your R-16 resistor if your engine really sounds like a diesel. you definately don't want preignition. what octane fuel are you running?

Just a guess... I have heard a similar description of this problem (not in a mercedes) and it turned out to be a deffective lambda sonda...

Right now I have chevron 93 octane in the car. I tried putting the r-16 back in, the sound was still there, but the car was even slower.... I seriosly think its something with my spark plugs or ignition system, because when I set the fuel setting back to normal, the car ran fine... a little slower than before, but quite a bit faster than with the fuel enrichment on, I suppose I will get the alternator, distributor, and spark plugs checked; I might as well just get a spark booster too...