Please help! Need "Dr. House" to diagnose this one.

Subscribe
Sep 28, 2012 | 10:01 AM
  #1  
I have a 1996 C280 with approximately 120k miles which I purchased for my son a couple of years ago. The car is great, and runs like a charm out on the highway, however there is a recurring problem with acceleration at low speeds. I have spent a lot of $$ trying to remedy this recurring problem.

In short the car is throwing a number of CEL codes, and conssistantly throws a camshaft sensor code. The cam shaft sensor has been replaced at least three times (by myself and by my local German car indy shop). The indy shop has also spent time with the vehicle and removed the valve cover, inspected the cam shaft clearance levels, and cam gear and tells me they are all within tolerances. At one point they replaced the throttle body actuator as well, but this problem has arose since.

The drivability issues are as follows: Car struggles to accelerate off the mark but only after it is hot. Hot humid weather seems to contribute to it, but the MAF sensor has been swapped out with no improvement. Seems the car runs borderline hot (110 to just below 120 degrees c on average). Auxiliary fans operate ok, I have replaced the aux fan relay and also the coolant temp sensor for good measure. Fans seem to cycle on and off ok. Running the A/C might be making the car run hotter and contribute to the drivability issue but I cannot be 100% sure. A/C has slow Freon leak. After car is hot and turned off, it always seems to have a very noticeable issue with the initial acceleration one restarted and placed in reverse or drive. The ignition at that point is being retarded or restrained by the CPU. When this happens, the gas pedal can be pressed all the way to the floor and the car will barely move. The car also seems to use an excessive amount of gas and sometimes smells “rich”. Once on the road, it struggles at lower speeds and the shifting from 1st to 2nd feels restrained and prolonged with very noticiable rough shifting in low gear.

Codes are as follows:
P1340 CMP Sensor
P0341 CMP Sensor circuit range problem (cam sensor replaced, cam magnet replace)
P0325 knock sensor
067 CMP signal implausible
081 maximum ignition retard on at least one cyl

Items replaced/troubleshot:
Replaced spark plugs, all sp wires, all coils
Replaced cam shaft sensor and camshaft balancer/magnet, physically checked tolerances and lifters, etc.
Sent out CPU for testing rebuild – came back tested good
Wiring harness in good shape
Replaced overload protection relay, aux fan relay, fuelpump relay
Replaced engine coolant temp sensor
Replace throttle body actuator
New battery (voltage a little low so replaced)
Replaced fuel filter
Tested different MAF

Bottom line, I can’t afford to throw parts at this any longer but I know it can be fixed if properly diagnosed.

Any insight into this or anyone with similar issues which they can share would be greatky appreciated!
I have a 1996 C280 with approximately 120k miles which I purchased for my son a couple of years ago. The car is great, and runs like a charm out on the highway, however there is a recurring problem with acceleration at low speeds. I have spent a lot of $$ trying to remedy this recurring problem.

In short the car is throwing a number of CEL codes, and conssistantly throws a camshaft sensor code. The cam shaft sensor has been replaced at least three times (by myself and by my local German car indy shop). The indy shop has also spent time with the vehicle and removed the valve cover, inspected the cam shaft clearance levels, and cam gear and tells me they are all within tolerances. At one point they replaced the throttle body actuator as well, but this problem has arose since.

The drivability issues are as follows: Car struggles to accelerate off the mark but only after it is hot. Hot humid weather seems to contribute to it, but the MAF sensor has been swapped out with no improvement. Seems the car runs borderline hot (110 to just below 120 degrees c on average). Auxiliary fans operate ok, I have replaced the aux fan relay and also the coolant temp sensor for good measure. Fans seem to cycle on and off ok. Running the A/C might be making the car run hotter and contribute to the drivability issue but I cannot be 100% sure. A/C has slow Freon leak. After car is hot and turned off, it always seems to have a very noticeable issue with the initial acceleration one restarted and placed in reverse or drive. The ignition at that point is being retarded or restrained by the CPU. When this happens, the gas pedal can be pressed all the way to the floor and the car will barely move. The car also seems to use an excessive amount of gas and sometimes smells “rich”. Once on the road, it struggles at lower speeds and the shifting from 1st to 2nd feels restrained and prolonged with very noticiable rough shifting in low gear.

Codes are as follows:
P1340 CMP Sensor
P0341 CMP Sensor circuit range problem (cam sensor replaced, cam magnet replace)
P0325 knock sensor
067 CMP signal implausible
081 maximum ignition retard on at least one cyl

Items replaced/troubleshot:
Replaced spark plugs, all sp wires, all coils
Replaced cam shaft sensor and camshaft balancer/magnet, physically checked tolerances and lifters, etc.
Sent out CPU for testing rebuild – came back tested good
Wiring harness in good shape
Replaced overload protection relay, aux fan relay, fuel pump relay
Replaced engine coolant temp sensor
Replace throttle body actuator
New battery (voltage a little low so replaced)
Replaced fuel filter
Tested different MAF

Bottom line, I can’t afford to throw parts at this any longer but I know it can be fixed if properly diagnosed.

Any insight into this or anyone with similar issues which they can share would be greatky appreciated!
Reply 0
Sep 30, 2012 | 02:38 AM
  #2  
Answer
Quote: I have a 1996 C280 with approximately 120k miles which I purchased for my son a couple of years ago. The car is great, and runs like a charm out on the highway, however there is a recurring problem with acceleration at low speeds. I have spent a lot of $$ trying to remedy this recurring problem.

In short the car is throwing a number of CEL codes, and consistently throws a camshaft sensor code. The cam shaft sensor has been replaced at least three times (by myself and by my local German car indy shop). The indy shop has also spent time with the vehicle and removed the valve cover, inspected the cam shaft clearance levels, and cam gear and tells me they are all within tolerances. At one point they replaced the throttle body actuator as well, but this problem has arose since.

The drivability issues are as follows: Car struggles to accelerate off the mark but only after it is hot. Hot humid weather seems to contribute to it, but the MAF sensor has been swapped out with no improvement. Seems the car runs borderline hot (110 to just below 120 degrees c on average). Auxiliary fans operate OK, I have replaced the aux fan relay and also the coolant temp sensor for good measure. Fans seem to cycle on and off ok. Running the A/C might be making the car run hotter and contribute to the drivability issue but I cannot be 100% sure. A/C has slow Freon leak. After car is hot and turned off, it always seems to have a very noticeable issue with the initial acceleration one restarted and placed in reverse or drive. The ignition at that point is being retarded or restrained by the CPU. When this happens, the gas pedal can be pressed all the way to the floor and the car will barely move. The car also seems to use an excessive amount of gas and sometimes smells “rich”. Once on the road, it struggles at lower speeds and the shifting from 1st to 2nd feels restrained and prolonged with very noticeable rough shifting in low gear.

Codes are as follows:
P1340 CMP Sensor
P0341 CMP Sensor circuit range problem (cam sensor replaced, cam magnet replace)
P0325 knock sensor
067 CMP signal implausible
081 maximum ignition retard on at least one cyl

Items replaced/troubleshot:
Replaced spark plugs, all sp wires, all coils
Replaced cam shaft sensor and camshaft balancer/magnet, physically checked tolerances and lifters, etc.
Sent out CPU for testing rebuild – came back tested good
Wiring harness in good shape
Replaced overload protection relay, aux fan relay, fuel pump relay
Replaced engine coolant temp sensor
Replace throttle body actuator
New battery (voltage a little low so replaced)
Replaced fuel filter
Tested different MAF

Bottom line, I can’t afford to throw parts at this any longer but I know it can be fixed if properly diagnosed.

Any insight into this or anyone with similar issues which they can share would be greatly appreciated!
It sounds like several issues.

My best advice is take it to the MB dealer for a diagnostic scan with the factory tool.


North America residents can subscribe to the Mercedes Benz Electronic Parts Catalog FREE...
http://epc.startekinfo.com/epc/subscribe.jsp


Here are some possible answers:

Has the camshaft ARMATURE been replaced, it has been superseded five times, the current part is MB# 110510043.

I suggest you remove and inspect the Flap resonance valve MB# 0001400431 for damage, if it is OK, re-install it.

There is a small air hose going from the upper to lower intake manifold, when it is damaged performance is horrible.

It sounds almost as if the catalytic converters or exhaust might be crushed/plugged.
Visual inspection + disconnect the exhaust from the manifold, run it to verify if some of the issues are suddenly gone.

I have dealt with the MB Wiring Harness Failure issue to many times.
Here is a link with extreme detailed data and pictures.
http://www.peachparts.com/shopforum/...s-failure.html

FYI:
* The engine control module has been superseded up to six times, depending on your VIN#.
* There are two fuel strainers in the tank, picture attached.
* The fuel rail pressure regulator has been superseded.

roy@pelicanparts.com


.

Please help!  Need "Dr. House" to diagnose this one.-w202_fuel-strainer_mwxqkf.jpg  

Reply 0
Subscribe
Currently Active Users (1)
 
story-0

6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)

Slideshow: Not every Mercedes design becomes timeless, some feel stuck in the era they came from.

By Verdad Gallardo | 2026-05-12 18:09:07


VIEW MORE
story-1

Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun

Slideshow: Yes, Mercedes built manual cars, and some of them are far more interesting than you'd expect.

By Verdad Gallardo | 2026-05-02 12:36:58


VIEW MORE
story-2

Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren

Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.

By Verdad Gallardo | 2026-04-29 11:19:28


VIEW MORE
story-3

8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine

Slideshow: Before curves took over, Mercedes mastered the art of the straight line, and some of those shapes still look right today.

By Verdad Gallardo | 2026-04-25 12:05:49


VIEW MORE
story-4

Flawlessly Restored Mercedes 190E Evo II Heads to Auction

Slideshow: The 190E Evolution II shows how a homologation necessity became a six-figure collector icon.

By Verdad Gallardo | 2026-04-22 17:53:47


VIEW MORE
story-5

Electric Mercedes C-Class Unveiled: 11 Things You Need to Know

Slideshow: Mercedes is turning one of its core nameplates electric, and the details show just how serious this shift is.

By Verdad Gallardo | 2026-04-21 13:58:06


VIEW MORE
story-6

Mercedes EQS Gets A Major Update: Everything You Need to Know

Slideshow: Faster charging, longer range, and a controversial steer-by-wire system define the latest evolution of Mercedes-Benz EQS.

By Verdad Gallardo | 2026-04-15 10:35:34


VIEW MORE
story-7

5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve

Slideshow: These overlooked Mercedes-Benz models never got the spotlight, but they quietly delivered more than most remember.

By Verdad Gallardo | 2026-04-13 19:35:45


VIEW MORE
story-8

Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping

Slideshow: A well-used 1991 Mercedes-Benz 300D with more than one million miles is now looking for a new owner, and it still appears ready for more.

By Verdad Gallardo | 2026-04-10 10:05:15


VIEW MORE
story-9

10 Most Reliable Mercedes-Benz Models You Can Buy Used

Slideshow: From bulletproof sedans to surprisingly tough SUVs, these Mercedes models proved that the three-pointed star can go the distance.

By Verdad Gallardo | 2026-04-08 09:55:49


VIEW MORE