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2004 E320 Wagon
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23 Posts
Discussion Starter · #1 ·
Ok, my first post here. Since I bought the car a few months ago the forums have been very helpful on some odds and ends things with the car. Today though I ran into an odd problem. I did a bit of of a search, but didn't find anything specific to this.

Car is 1997 C280 about 132K on it. Car was a one, possible two owner vehicle. Over the past couple of months I have had the cam position sensor replaced (was getting a CEL refering to this), the magnetic cam positioner, coolent flush, oil change and a couple of the fuel vapor lines replaced back by the gas tank. Soon, will get a complete transmission service and control arm bushings done. Overall it has been a very good car.

Today when doing a couple of errands had driven the car a bit and when I left the store car started fine, put it in gear and it started bucking, almost like the brake was on. I slowly drove it around the lot after checking that the parking brake wasn't on. Put it in park and when I gave it some gas the RPMS wouldn't go much over 1K and the car felt like it was running on 2 or 3 cylinders. It did idle just fine. Got out and checked what I could to see if any loose wires or anything. Also tried disconnecting the MAF to see if that was a problem, but it made no difference. Tried on and off for about 45 minutes and the car still had the problem. The weather here has gotten a bit warmer and I was running the A/C before this happened. Prior to this happening I had been getting around 18-19 mpg mostly city miles.

So just curious what I should be looking for on this.
 

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2001 CLK55 AMG, 2002 C32 AMG
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1,637 Posts
well, if it felt like it wasnt running on all cylinders then it probably wasnt haha. i recommend having the codes read on the car. this can tell you if it was actually misfiring and which cylinders it was.

when was the last time the spark plugs were changed. you said that you checked the wires, did you remove the spark plug cover and check them? i doubt its the wires. if it is misfiring its most likely the coil pack.

i think you are on the right track with all of the other maintenance you are doing and the stuff you want to get done. keep it up :)

like i said, before replacing anything i recommend having the codes read, and then let us know how that turns out. good luck.
 

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C 230 1997 42000 miles
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265 Posts
I'll second the coil pack.

One of your coils may have a hairline crack in it. This happened to me and the crack was barely visible to the eye.
 

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2004 E320 Wagon
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23 Posts
Discussion Starter · #4 ·
Thanks guys for your help!

Later this year I'm driving to Disneyworld for vacation, so I'll get to see part of the south, that is why I'm wanting to make sure all is well with the car. I now have one frustrated mechanic! He ran tests from front to back and back again. No codes in the system. MAF checks out ok as well as all fuel systems, pressures, etc. All the ignition, wires, coils everything ok. However he finally noticed a tiny little drip from a heater hose and pipe that was leaking on to the crank position sensor and getting it wet. He removed it, cleaned it and the car ran fine. Tomorrow he'll replace the hoses and possibly the sensor since he'll be working in that area. I think here in the desert there may be parts that just dry out from the heat and lack of humidity. I did see some water under the car, but thought it was from the A/C and not a leak.

Perhaps this will help someone else if they have an odd running problem.
 

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2001 CLK55 AMG, 2002 C32 AMG
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1,637 Posts
usually people with cps sensor problems have issues starting the car when its hot, right after they turned if off, and they have to wait 30-few hours to start the car again. i guess coolant dripping on your cps could cause your symptoms. sounds like an easy fix :) good luck.
 

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2004 E320 Wagon
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23 Posts
Discussion Starter · #6 ·
Got the car back tonight and fingers crossed it's running smoother than it did before. Never had any problems starting it hot, though we've not had any real warm weather yet. Give it another month. Leaving the garage tonight, in stop and go traffic with the A/C on the temp gauge read just a little above the 80 mark. Good news from the garage, the bill was lower as the sensor they initially ordered by my VIN was more expensive. The one they used matched that in the car and it was less expensive.
 

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1994 C220 (W202) Classic and 1998 C240 (W202) Elegance
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342 Posts
I hope you're car keeps running, but how come the sensor indicated by your VIN and the one that was in your car is different? Did the previous owner replace the CPS with a non-standard one to save cash?

Could this have anything to do with the longevity / durability / efficiency of the sensor?
 

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2004 E320 Wagon
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23 Posts
Discussion Starter · #8 · (Edited)
I called the garage back today and asked about the different sensor. Their explaination was that they will order parts by VIN, however sometimes what will show up may be different due to MB part numbers. As a side note, I work in a vacuum shop P/T and Hoover has changed all their belt numbers, making it a pain to cross reference back to an old belt. The sensor that came in was for an older vehicle without the electronic fuel injection. The mechanic said the sensor that came out of my was was marked as MB and not a non-standard one. It may have been replaced in the past, but he was not able to tell. The prior owner was very picky about maintaining the vehicle, as it was his wife's car. He bought her a new 300 for Christmas, thus selling this one.
 
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