bheng

So driving back from a date last night...and i felt that the gas wasnt responding anymore. i thought it was weird. then car started to sputter. noticed rough idle.

it died on me at every stop light. somehow when i waited a bit and started again, it was able to roll to her house before kicking the can.

had to get the car towed across a two cities to get home. and todays presidents day so i no go with the dealer. from what i read on the threads, this sound likes a CPS problem.

started it last night to experience rough idle and no gas response from the gas pedal. however, those with cps problems didnt sound like the car was completely unresponsive to the gas pedal so im worried that its more than that.

however, going to kragen to see if they have a cps part available. do you think this would suffice or should i be using a genuine mercedes part?

bheng

mis3

My experience with bad CPS was as follow:

I was driving and the engine died all of a sudden. I stopped the car and attempted to start the car. The car would crank but did not start. i waited a few minutes. cranked again and it started. I let it idle for a few minutes and it died again all by itself. This repeated a few times and I finally called MB roadside assistant. It took the tech 20 minutes to replace the CPS.

bheng

how much did it cost for the job, mis3?

i should have done that last night...but wasnt thinking how road side assistance would destroy me but the towing probably cost just as much.

-___- i should have just called road side assistance. LOL

mis3

I am in Canada so everything is more expensive here.

Cost of the CPS was $99. Labor was $180. Total invoice was $313.
The price included roadside assistance.

Louie D

Call your Benz dealer my service department is open here you might want to check with yours to make sure there closed today if you have not already. Yes go with OEM parts if you can..

bheng

i hope they are open today. if not, i can wait for it tomorrow. i hope they have the part in stock so i dont have to wait a couple of days for it

i prefer oem but the clk is my dd

thanks for all the help guys! will post pics of the install to put up as well

UPDATE: so i called the parts department. the part costs 171. does that seem right?

Glyn M Ruck

This does not sound typical of CPS only. Bad CPS usually causes poor or no starting. Most CPS failure is somewhat temperature dependent. They don't work when hot.

Standard roadside assistance fix is to pour a bottle of cold water over the thing to achieve a start & get the car home or to a dealership.

$25 to $55 at RMeuropean.

mis3

My mistake. Roadside assistant was $99 and the CPS was $179.

Part no: 003-153-28-28

bheng

I would think it would be CPS only because it sounds just as what mis3's predicament. the car was hot when this happened. it does start, then a rough idle, then dies.

I do notice the RPM meter bouncing up and down (slowly) when i tried to start it after i got the car into my garage. also, it does not respond to any gas pedal input.

does that sound like anything.
I think i will purchase an obdii reader today to get the codes and look them up online before i buy any unnecessary parts

mis3

I checked some online places and the Bosch one is $55. Not sure if this is OE.

If you can get it with this price, go for it. I changed mine in Dec-98, the roadside assistance guy said he was surprised that mine had not been changed already. Apparently there was a bad batch in 2003-2004 production cars. If this is true and yours was never changed, you may as well change it now to avoid further disruption.

He replaced it on the spot. The CPS is behind the engine and he had to sit on my engine to replace it!

Glyn M Ruck

An M112 engine won't run if it does not know where TDC is - provided by CPS (other Benz engines like the M271 will run on the cam sensors). It will also not enable start if there is no signal from the CPS, temp sensor etc. Of course intermittent output from the CPS will cause erratic conditions. I would replace CPS as a matter of course but CPS trouble when hot usually makes a restart impossible until the CPS has cooled down.

Good luck

This is the EIS inductively energised key, handshake & start process. CKP is the CPS

Glyn M Ruck

You need to read those codes.

Once you have replaced the CPS - other things to check are:

TPS (Throttle pedal position sensor)
Fuel pressure at schrader valve on the rail is >3.8 bars WHILE CRANKING! (When last did the car have a fuel filter?)
MAF
Vacuum leaks.

Rudeney

My understanding is that the CPR isn't even used to determine TDC - it is used for nothing more than to tell the ECU that the engine is actually rotating. If no CPS signal is sent to the ECU, then it assumes the engine is frozen and not rotating and therefore does a fuel cut-off, for safety reasons. Symptoms of a failed CPS are that the engine just shuts off -like turning the key to position 0 - with no error codes, hesitation, stuttering, etc.

Glyn M Ruck

No - on the M112 it is used to determine TDC. You are however correct for start enable it has to confirm that the engine is not rotating so that you can't engage the starter motor into a spinning ring gear. The ECU in the diagram above also interrogates the temp sensor to establish engine temperature & whether mixture enrichment is required or not for start.

Partial CPS failure usually requires a cool down period before a restart will be enabled.

Total CPS failure will result in no start.

The vehicle should throw one of the following codes. P0335 being the most common.

P0335 = Crankshaft Position Sensor A Circuit Malfunction
P0336 = Crankshaft Position Sensor A Circuit Range/Performance
P0337 = Crankshaft Position Sensor A Circuit Low Input
P0338 = Crankshaft Position Sensor A Circuit High Input
P0339 = Crankshaft Position Sensor A Circuit Intermittent

bheng

so as an update from last time.

Last night I ran the on board diagnostic....read 11.9-12v. the car would crank but not start....great....so this morning, got a trickle charger from a friend, gave it a 30 min charge. took off the trickle charger. it read 12.5v

started the car, it starts! everything is good. except see the rpm drop a bit, then the car starts to shake and my car automatically revs itself up (keep in mind im in 'park'). then i rev it a bit and i feel it bog down again....it was about to stall out but the car kept it going my allowing it to rev again. i think i will allow the car to warm up in park to see if it will die out under some load so i can get it to throw the code because as of right now, there is no malfunction being thrown....

will keep you guys posted and thanks glyn as well as the rest of the members here patiently replying to this thread... id be at the stealership without you guys!

UPDATE: so i let the car run for 18 min from cold start. the temp is warmed up to normal driving temp and it dies...dies when you put it under load, dies when you it in gear. battery voltage when the car starts 12.3v...drops to 11.x...raises to 13.7v and then dies. the annoying thing is that i am not getting any malfunction messages on the dash. and my obd ii reader isnt picking anything up.

Glyn M Ruck

Your voltages are low. Have you load tested the battery?

Mka77

I suspect a battery about to go.

As Glyn said, a load test would do the soul good. Hopefully that's all it is bheng.

bheng

noob question.... how do i do it?

i mean when i used a trickle charger...the power went back up and is holding charge. but im down to do a load test...i suspect to use a multimeter?

Rudeney

Oddly enough, the two times I've dealt with a failed CPS on an M112, there have been no codes. Either the engine dies smoothly, just like switching off the ignition, or during start, it rotates but fails to fire. Go figure!

Glyn M Ruck

Oh! Rodney - I have seen occasions it throws no codes as well. Most recently on a friends S Class. Nada, nothing. zilch! Changed the CPS & she fired right up.

More irritating is the dual failure of fuel system & CPS together & no codes. Shot CPS & shot fuel pump or solenoid & NO codes. OBD are not perfect. Had this recently on a friends W202 C240 & it had a blown fusible link!

bheng

LOL well i two day shipped the cps. once i get it, going to install it and see how it goes. HAHA will def report back after i

mis3

Where did you get the CPS? OE?

bheng

autohausaz

its bosche so oe

and it was cheaper than buying it from kragen....even with shipping for a 2 day ....-___-

Glyn M Ruck

You take it to a battery shop that can place it under load & see how quickly it dumps it's charge. Many batteries will hold a surface charge but the minute you load them the voltage goes south.

bheng

oh okay. i'll call to see if the local kragen will be able to perform this for me