Not much Power off line? - Mercedes-Benz Forum

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post #1 of 3 (permalink) Old 12-30-2006, 02:22 PM Thread Starter
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Not much Power off line?

I have a 72 280 SEL with a 4.5 I have owned the car for about 12 years. In that time I have never been able to get any real power off the line with this car. It is so bad sometimes that I have to pump the pedal 3 or 4 times to get it going 45. Once the speed is up, 65+ it runs smooth. The engine has been tuned and does not miss. I have tried changing out the filters but it seems to still have trouble getting enough Gas fast enough. I am guesing the PSI to be about 15.

Even though the 4 door car is not worth much, I love it as a driver when all of the filters are new. It just doesn't take long for me to notice I am pumping the gas pedal again. Any idea's would be of great help. Maybe I should just change the engine out?
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post #2 of 3 (permalink) Old 12-31-2006, 07:21 AM
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Before y ou change out the engine, I would suggest a compression check. Since the car doesn't miss, I'm guessing the timing isn't too awfully off. Do you smell gas at the tail pipe? Is the exhaust blue? If the engine is good (good compression, no blue smoke), then you have a problem with your fuel delivery or an associated sensor.

This is an interesting one - keep us posted!
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post #3 of 3 (permalink) Old 01-01-2007, 10:47 AM
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Mounted on the throttle body is the TPS (throttle position switch) a large black plastic box. With the key on, engine off, rotate the throttle linkage slowly. You should hear 20 distinct clicks from that switch. Each click tells the computer to open the injectors longer and longer to provide the right amount of fuel in relation to air intake. If this switch is dirty, worn, or electrically open then fuel delivery will be affected. The black cover can be removed while the switch is still attached and the strips of copper can be cleaned with a pencil eraser. You can also watch the finger of the switch swipe across the contacts. You also should remove its multiwire connector and clean the contacts then apply di-electric grease to the contacts and reconnect. Also some of these engines will perform better if the air temp sensor mounted in the air cleaner inlet snorkle is left disconnected! Report back!
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