Not so fast on the CPS Success
Thread Starter
Junior Member
Joined: Nov 2010
Posts: 27
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From: Maryland
C240 Wagon
Not so fast on the CPS Success
So perhaps I have committed the sin of hubris or maybe I vexed one of the Teutonic deities but the net result is the same. My newly equipped with CPS C240 Wagon ain't running. I took it out for a test drive today and it DIED on my street. Then it would crank (most vigorously) but not start. I thought I might have to push it back to my garage but it finally did start and run enough to get it into the barn.
To review: I replaced the CPS with a non dealer item from a trusted local parts house on Sunday. The car started and ran fine in the garage after I reassembled it. My daughter was going to drive it today and said it wouldn't start. I was on a concall so I couldn't attend to it immediately. She came back in and said that it started when she PRESSED THE ACCELERATOR! I know, huh? Later I confirmed this phenomenon. Finally, I went to drive it for a bit and it just quit.
I don't have a scan tool so I'm in question mode. Should I question the CPS itself? Should I tear it down and put in an OEM model? Should I jack up the air cleaner housing and slide a new W203 underneath?
To review: I replaced the CPS with a non dealer item from a trusted local parts house on Sunday. The car started and ran fine in the garage after I reassembled it. My daughter was going to drive it today and said it wouldn't start. I was on a concall so I couldn't attend to it immediately. She came back in and said that it started when she PRESSED THE ACCELERATOR! I know, huh? Later I confirmed this phenomenon. Finally, I went to drive it for a bit and it just quit.
I don't have a scan tool so I'm in question mode. Should I question the CPS itself? Should I tear it down and put in an OEM model? Should I jack up the air cleaner housing and slide a new W203 underneath?
Thread Starter
Junior Member
Joined: Nov 2010
Posts: 27
Likes: 0
From: Maryland
C240 Wagon
Resolved
So perhaps I have committed the sin of hubris or maybe I vexed one of the Teutonic deities but the net result is the same. My newly equipped with CPS C240 Wagon ain't running. I took it out for a test drive today and it DIED on my street. Then it would crank (most vigorously) but not start. I thought I might have to push it back to my garage but it finally did start and run enough to get it into the barn.
To review: I replaced the CPS with a non dealer item from a trusted local parts house on Sunday. The car started and ran fine in the garage after I reassembled it. My daughter was going to drive it today and said it wouldn't start. I was on a concall so I couldn't attend to it immediately. She came back in and said that it started when she PRESSED THE ACCELERATOR! I know, huh? Later I confirmed this phenomenon. Finally, I went to drive it for a bit and it just quit.
I don't have a scan tool so I'm in question mode. Should I question the CPS itself? Should I tear it down and put in an OEM model? Should I jack up the air cleaner housing and slide a new W203 underneath?
To review: I replaced the CPS with a non dealer item from a trusted local parts house on Sunday. The car started and ran fine in the garage after I reassembled it. My daughter was going to drive it today and said it wouldn't start. I was on a concall so I couldn't attend to it immediately. She came back in and said that it started when she PRESSED THE ACCELERATOR! I know, huh? Later I confirmed this phenomenon. Finally, I went to drive it for a bit and it just quit.
I don't have a scan tool so I'm in question mode. Should I question the CPS itself? Should I tear it down and put in an OEM model? Should I jack up the air cleaner housing and slide a new W203 underneath?
I hooked it up and got the P0335 Crankshaft Position Sensor DTC and P0221 Throttle/Pedal Position Swich B Error. I checked the CPS harness and actually removed and replaced the new CPS with another. Now I have a spare for the glove compartment.
I also replaced a cracked PCV hose that connects to the rear PCV chamber on the driver's side valve cover. It connects into the elbow between the intake and the MAF.
On restart, the car ran super rough and threw the P0335 DTC again. That's two CPSs replaced so I'm pretty sure that's not it.
EDIT: As of now, it's running very well. I cleared the DTCs, did the Throttle Reset procedure and drove it around town for 15 minutes. It accelerated and decelerated smoothly and idled quietly and smoothly. Looks like I made it through another DIY fix. *knocks wood* Well, I guess it's time to tempt fate and do the spark plugs this weekend.
Last edited by OldSchoolC240; Jan 26, 2012 at 02:58 PM. Reason: Provide final analysis.
