Classic CPS symptoms. Cheap and very common fault. Located on top of trans bell housing at rear of engine.

 

with a bad maf,it will do what you say it is doing exactly with a failing cps.
About 70 bucks at autohausaz.com for the crankshaft position sensor and diy on benzworld.org w210 section and mercedesshop.com resource section diy articles.
easy if you take your time and follow instructions per above

lastly please stop jumping wires and trying to short out relays to track down the problem yourself.Either jump here first or best to keep hands off an mb relay system anything to do with the das or the ignition,before asking.You can do serious,costly damage,far in excess of the $70 repair of the crank sensor

 

Thanks for the advice, fellows.
I've now read a lot about the CPS, and question whether that is my problem since the symptoms are a bit different.
The car always starts right up when cold, and always within one second of turning the ignition key. It runs about 20 minutes, whether on the road or at rest in Park. Then it dies suddenly with no sputtering. Its like the key has been turned off. When I try to restart it, the starter just turns over and the engine doesn't kick at all. After 20 minutes or so, the car starts right up. Then it runs about 10 minutes and stops again. Then it has to cool off another 20 minutes before starting.
I cracked the fuel line in the engine compartment and no fuel comes out when I turn the starter over (during the "dead" time). This tells me the problem is related to the fuel delivery system. (I suppose a bad CPS is not going to stop the fuel delivery system from working. ?)
But, remember in my first post that when I jumpered the larger leads in the relay during the "dead" time, the fuel pump worked. I think this rules out the contacts in the fuel pump being the problem.
I know the relay is good, since I replaced it with a new one, so the problem lies somewhere in the source of voltage to trip the relay. Right? I understand the voltage to the leg that crosses to the other side when the relay is energized is constant and connected directly to the battery (which is why the fuel pump works when the relay is jumped). I tested that during the dead time, and voltage was there. Voltage is sent to the fuel pump when the key is first turned on, and stops when the system is pressurized. Then voltage is again sent when the key is turned to the Ignition position, to start the car. I need to see if voltage is sent to the relay when the key is turned on during a dead time, but I am sure it is not. Does anyone know what controls the voltage that trips the relay?
The fuse number six that protects the fuel pump is ok. I removed it and reinserted it.

Joe

 

Classic CPS. Gets hot; stops sending signal. Think arc'd points or broken rotor on old ign system.

*edit* when cold, you can hit it with a heat gun and prob duplicate the fault if you wish.

 

Failing CPS from heat is a common issue and since the CPS relays crank speed
values to the ECU to be used to calculate engine rpm,ignition timing and fuel injection timing,if it is going bad at first it may rear its ugly head by simply not starting when trying to start after a short drive and then you sit for a bit and it starts right up.A few weeks later it gets worse and it starts stalling out as you stop at a light and you coast to the curb only to have it start up after 20 minutes.Fuel will not get pumped if the ECU is not getting the signal from the sensor that tells it what it needs to send to the injector circuit.Other sensors come into play like the cam position sensor,but the car will run with a dead or bad cam sensor it just won't run well
failing cps car will start up when cold.Heat expands the design and therein causes the problem,and not a bit different than what you are experiencing
when it goes bad completely,you won't go completely

 

Had mine replaced last night, I'm not good enough for DIY on this. $200 for the job with part. I had the exact same symptoms, had it replaced and now its good to go. One thing to look for is a spacer that needs to be in place when you change it out. Without it you will FREAK out when it sounds like your starter IS GONE.

 

if you diy make sure to read the part added lately about indexing it to the ecu.Very simply done after you replace the crank sensor.

 

Where is the DIY section that explains this? I haven't been on the site for about 4 months and all the DIY stuff was at the top of the section?

 

Had Similar problem in my 96 E320. Would run fine, but once in a while it would not start, cranking just fine but no fuel. I checked every connector I could first, then tried again - it started. Next day, same problem.

Basics of trouble shooting - recheck normal operation. Only problem with that, is you wouldn't be checking anything if it operated normally! When you have a ghost electrical issue, start looking at the condition of wires. A few minutes of replacing old, brittle weathered wires will save you $$ on whole parts that are not bad. I was lucky in that the previous owner had recently replaced the CPS, the starter, fuel pump and relays. His efforts allowed me to find a better solution than throwing tons-o-money without knowing the source of the true problem - corroded wiring.

As for your issue here is what went down under my hood -

Now, the hard part (#1 possibility) - there is a wiring harness that runs from the transmission back to the ignition circuit, including your CPS. Look at it closely for cracks / corrosion at the connectors and any sign of having been too hot at some point. Mine was brittle and corroded beyond recognition in places. I took the whole thing out disconnecting from 3 points at the tranny, one from the starter, and at the terminal at the drivers side front of engine bay. Careful cutting, splicing and solder if you can - then re-wrap after replacing almost every inch of wiring with correct gage. Takes a few hours. Car started right up - until the next day.

Hard part (#2 possibility) - determined to drive this otherwise fine automobile, I had help crank the car over while I wiggled wires. Wear gloves, short sleeves, and don't lean against the car - including touching anything but the wire bundle you are going to wiggle. With pretty (aka useless) covers from the engine removed for access to fuel injector area routed wires have help turn the ignition over. Be sure to keep air meter sensor wires and throttle body assembly in place to keep the situation real for the ecu. after about 5 minutes of attempts, we got the car to start, then I was able to narrow down to a bundle, which got its sheathing removed, then to a single wire that ran across the back of the engine bay (firewall) into the relay and main connection point at the passenger side rear. There was one wire that was broken from the "natural" bend in the harness. Seems temperature was a factor in allowing the wire to flex ever so slightly, giving a start condition sometimes and no start the others.

After carefully splicing in a new few inches of wiring and re-wrapping, the car has been super dependable.

 

the OP has a 99 not prone to faulty wiring or bad harness problems of the M104.You are making his trouble shooting problem far to troubling
His symptoms are classic CPS it happens to almost every m112 or m113 at one time in their life.$57 bucks and a half hour,fixed.
Your M104 would have been diagnosed in a different manner ,you had different symptoms.
basic trouble shooting M112 and M113 hot start/stall no start, cool down restart. CPS simple as that.

 

They all moved over to benzworld.org w210 section diy stickies and mercedesshop.com
or just ask or search

 

I have exact the same problem. any news from your car?

 

Possibly a clogged cat?

 

long as you blocked the intake hose?Air is getting in someplace it should not be getting in
Look for cracked or broken vacuum lines or intake tubing.Do you know how to search using a propane torch with the flame off?

 

I have a 2000 E55 with 116k miles and in the last 1k miles the car has a hesitation when leaving from a dead stop and also when you press the throttle past the kickdown while rolling. If you ease into the throttle like a grandma it is ok but don't try to pull out real quick or the hesitation will start. At cruising speeds you would never think anything was wrong.

Around 5k miles ago I replaced the plugs, wires, air filters, CPS sensor, and the MAF sensor and the car ran like a charm after that up unitl the last 1k miles. I have no codes showing and need advice as to where to start tracking down the issue. Would a clogged catalytic converter cause these symptoms? Missing the power of the AMG beast.

Thanks in advance for the help.

 

plug wires? They last forever if not abused or set on fire.
What brand did you install and what type plugs did you install. If you used multi tip dump them and install oem. Where did you get the maf from? all likely culprits for off idle acceleration issues.

have you performed a trans adaptation reset to see if that puts a fire under the beast?

 

Used magnacor wires and bosch platnium plugs, Used a bosch OE MAF sensor and have also performed the tranny reset.

 

have been known problem makers and drive people to fits tracking down performance issues when installed. OEM wires usually solves the issue.
NO magna's,no k/n air filters, no multi tip plugs

 

I own a 1999 E320 4-matic. As I have been living abroad for 9 months it has been sitting in my garage since May. Needless to say, the battery was dead upon my return. I tried charging it w/o luck and figured that it was bad. Took it down to Pep Boys and had it checked. No problems were detected, and they charged it for free. The next day I took the car down for safety and emissions, and it failed emissions. BigO told me to do a 50-mile driving cycle to clear out gunk and re-build computer values, which I promptly started. However, after about 3 miles, while very slowly going over a fairly big dip in my neighborhood, the car just died. The starter turned over, but it just would not fire. After approx. 30 minutes I tried it again and it started fine. Drove the 500 feet to my driveway, and it died again. Same thing happened - let it sit for a while and it started fine.

As a non-car guy, I don't know what this could be except for maybe some bad connections in the alternator? Any advice will be very helpful. PS. It's only been 2,000 miles since its last dealer service.

 

It sounds like it may be a Crank Position Sensor (CPS). When they start to go bad the symptoms are not starting when hot but starting after the car has had a while to cool down. It is not too expensive and pretty easy for the average DIY mechanic to put in.

Good luck.

 

Thanks for your quick reply, Richard. I will certainly look into this. Based on your reply, I did a search and came up with this http://www.benzworld.org/forums/w163...t-its-not.html thread. I'm not sure that I understand it correctly, but is it saying that with a long cool down period it is the MAF, not the CPS, or is it telling me that a long cool down period is consistent with the CPS?

 

The long cool down period is referencing the CPS.I would suggest running a bottle of fuel injector cleaner on this tank to clear anything up since it was sitting for 9 months.

 

Try this link for info on W210 (your car)

http://www.benzworld.org/forums/w210...-pictures.html

I don't think the duration of the cool down period is a definitive parameter. Especially when it involves the gradual failure of an electronics part. That time will also depend on lot on ambient temperature -- it's winter in US now.

If you read the link you'll see that some posters reported 30 min before restart that's why I made the suggestion. Good luck.

 

Thanks for your previous help! I ordered the part and located the CPS at the rear of the engine. My new problem is that the nut looks like a specialty part that I don't have a tool for, almost like an inverted torx nut! Looking at some web sites I think the part number is N910142006001. Does MB use specialty parts so that you have to go to the dealer to have these replaced? Any help will be appreciated.

 

possibly the MAF?