In trying to fix my limp mode problem, I changed the conductor plate and refilled tranny oil. With my Autel Diaglink I read and deleted fault codes but now the engine will not even turn over. I turn the key and and everything on the dash lights up (radio, dash lights etc) but there is no engagement of the engine at all. I get nothing. Okay fells what did I do wrong and how can I get the start again. Have I wiped out my codes. I have been using the Mercedes software for the 320 SLK

 

SrWilliams, I had the same problem a month ago. All dash lights worked normal but when I turned the key to start there was nothing (the engine did not turn over). My problem turned out to be a bad battery. My battery passed the load test at AutoZone but the readout said that the battery had only 50% capacity. AutoZone put it on their charger for 45 minutes and the battery passed the load test again but still the readout said that the battery had only 50% capacity. I tried the charged battery and the engine still didn't turn over. I purchased a new battery and the engine started right up and everything has been fine since. You may only have a bad battery. Get it checked. Hope this info helps.

 

Tbirdtony:

You are so right on as I sent the night reading all of the car forums who experienced this problem with n o start after clearing codes and consensus was bad battery. I trickle charged the battery over night and got it to 100% but I did not try to start the car. But instead took the battery over to auto zone and it is being charged by them as well. In a couple of hours I will try to start the car with the battery. If it does not turn over I will use a battery from one of my other cars to see if that will start the car.

I just cannot believe simply erasing codes with an OBDII will cause a car to start. the way others in other car forums explained that spending two days reading and erasing codes probably caused the battery to drain. I think a good indicator of this is even though my dash lights were working and the headlights came on yesterday, the spoiler was stuck in an up position and would not close. Instead, the spoiler warning button was flashing, which I read somewhere indicates battery issue

 

SrWilliams, If the battery is a few years old you may want to replace it. I tried charging my old battery with an 8 amp charger, with an over night trickle charger, and AutoZone tried to charge it too. None of the charges gave the battery enough of a charge to work in my car even though the battery passed a load test. It seems that the Crossfires need a good strong battery. Hope your issue is corrected with an easy battery replacement.

 

Man I am praying it does. This whole limp mode mess has been a nightmare for me. I am so close to chucking this car over the limp mode matter. Now I am to the point where the car will not even start all because I was erasing fault codes. I will get the battery back in an hour or so. Please cross your fingers for me

 

I noticed that mine was running down the battery and would not start. Of course I tried charging it, and the tester on the charger showed it was back in the green, but then it lit the dash light, fobs opened the door, but no start - just the radio came on and lights worked, but no start. - just the typical SKREEM symptoms - two quick starts and kill, then nothing. I disconnected, reconnected after ten minutes, and same thing again. It was the SKREEM failure. It took a long time to find the solution for that. I put in a new battery - still the same thing. So then I spent months trying to find a solution, and MDP was what I came up with. I sent them the SKREEM module, the two keys and the ECM and they fixed it in one day. They sent the parts back and it was a simple plug and play - fixed, starts right up every time, no codes - so you may have a non-functioning SKREEM module, which MDP can fix. Perhaps the combo of low battery power and clearing codes does something to the SKREEM module. If you get a good battery in it and you still get a no-sart, then it may be a SKREEM problem.

 

Wolfstaker, I think you are correct in that the low battery power can do damage to the modules on not just Crossfires, but most Mercedes. A battery left unattended over the winter could cause a variety of module failures as the voltage goes down slowly over time.

 

My car cuts out at 2000/2500 rpm.
Car would start when cold, but not when hot. Got fault code for Crank sensor. Replaced sensor, car started but same problem. Replaced sensor again. Replaced battery. Car started but when revs hit 2000/2500 rpm car just dies. Restarts but won't rev.
I'm now thinking faulty O2 (Lambda sensor), clogged/collapsed Cat', or possibly blocked fuel filter. But where do I stop chasing the fault !!!!
I even thought it could be power relay module or ECU, so bought them but now I find out that without specialist software you can't reprogram them, and you need do do SKERM & Keys at the same time, and I cannot find anybody local in UK to help.

Any assistance really appreciated.

 

I would try replacing the RCM first. It is the most cost efficient solution.

 

DerrickRL "Got fault code for Crank sensor. Replaced sensor, car started but same problem. Replaced sensor again"
ONLY a Bosch CPS will work correctly. If you used any brand other than a Bosch expect problems.
A know good RCM is always a good place to start as is a known to be good battery.
Throwing parts at is an expensive way to fix a problem; Better to get the car scanned for diagnostic codes and have a starting place to make repairs.
Is the check engine light on? Then there is a code. Often a bad RCM will not activate the Check engine light nor throw a code.

Again from you: "'m now thinking faulty O2 (Lambda sensor), clogged/collapsed Cat', or possibly blocked fuel filter. But where do I stop chasing the fault !!!!" all of those problems you mention will have a diagnostic code. You need to scan the car, before buying more parts.

PS. no programing of RCM required. You just remove the old one and install the new one. However, the "ECU" properly called the PCM, Powertrain Control Module, does require programing; It can not simple be replaced with another as the VIN is specific to the car and it must match up with the SKREEM.

 

Hi,
Car starts but won't run over 2500rpm, Bought second hand RCM, fitted it and nothing worked, so that appears to be a 'dud'.
Working on it today, followed all instructions in workshop manual for checking Crank Sensor, next step tomorrow to pull the CPS again.
Noticed in manual it says replace Tone wheel but i suspect that is a gearbox out job, the tone wheel looks about £/$10 but will cost me a fortune if gearbox has to come out.
Anyone know what the resistance is if you measure across the CPS to check if it is good or bad rather than just spending $60 each time on a new CPS.

I still haven't seen on line anyone else with the rev limit issue? Any ideas?

 

You are diving down a rabbit hole; You can spend $60 on a CPS addendum, but if it isn't the correct part you will never fix your problem.
You can't buy a second hand RCM and expect anything other than trouble.
Did you comprehend post 9 and 10?
Not given you a hard time; STOP and answer the questions. Correct the items above, THEN scan the car.
Are you a member of the UK Crossfire club? Maybe someone there can help.

 

Hi.
Only fault code that shows is for crank sensor P0335 when car stalls and engine light comes on. Codes clear, car starts, ticks over but if revved cuts out and same fault code appears. Second hand RCM was worse than mine so sending that back as was under a 7 day warranty along with PCM. Everyone I spoke to in the UK is baffled by the not revving over 2500 rpm, no one seems to have come across that fault but found a discussion on this sight about the lack of revs and the fix was cleaning the CAT, so i really think i have a number of issues going on.
Spoke to a Crossfire parts specialist in UK and they said 3 possible causes, CPS, Bad connector or cable, bad PCM. I followed all of the instructions in the workshop manual to check voltages, etc and cannot find anything wrong. Manual suggests replacing CPS.
I found a specialist in UK that repairs ECU's (PCM) but they said they have problems with the codes for Crossfires, so said they will look at it for me and if they can't find problem and fix it they will not charge me.
Bought third CPS today, which again is a BOCSH (second was a BOSCH) and will pull that to see if I can see anything that has caused the problem and fit the new one.
The Crossfire is a fairly rare car in the UK so finding anyone who knows how to fix them is difficult. I've had mine 10 years now and always been able to solve problem but this one has me beat. I'll try the owners club, thanks for the suggestion.

 

I'm getting the impression that you are revving the car while in your garage without a load. Yes?
The Crossfire has a programed limit as to unloaded RPMs. I noticed it myself awhile back. My car did not stop running, but it did not want to get much past 2500 RPM. I did not force the issue and try and make it go beyond 2500 RPM. I was doing something in my garage on the car, but I can't remember exactly why I was revving the engine.
I suggest when you have a good RCM and have the Bosch CPS installed, clear all codes and then take the car out for a gentle drive and see how it responds.
A bad CPS will kill the car when out driving, but often after the car cools, it will start and run normally until it gets hot, and then again stop running. So replacing the CPS with a BOSCH will correct that problem. It has been suggested that the connection at the CPS is to blame, but that has not been definitively proven. If you have the CPS out inspect the connector carefully. A new Bosch does fix the initial no run while hot problem. I had the OEM CPS problem years ago and installed a Bosch replacement. That replacement is still in the car ten+ years later with 80,000 miles on it and doing fine.
Most scan tools will not dig down into the manufactures codes. They are OBD II scanners only, so you may be missing some information. The Crossfire has a diagnostic system that is unique unto itself. Getting the correct scan tool is important when digging down to fix some problems. Not knowing what tool you have I suggest reading the Scan tool info here on the website and decide for yourself if you need to, or want to get another scan tool.
Testing for exhaust back pressure is fairly easy.: remove forward O2 sensor and install adapter with PSI gauge. Kits available on ebay, or take it to a shop that works regularly on Mercedes and have them preform the test. Should not cost very much. If you get a kit yourself the pressure should not read above 3 PSI if all is well.

PS I took that heat shield off that is just to the rear of the CPS as it makes it much more difficult when servicing the CPS to have it there in the way. I ground the bolt down a little so it wasn't quite so long then screwed it back in it's hole.

 

DerrickRL, I tried the no load rev on my SRT6 just now and it would not go above 3800 in park, but it did continue running. However my car is tuned and so that RPM limit may be different on a original equipment car . As I recall my Limited didn't get so high on the RPMs, and again it did not stop running, but I can't try that now as my valve covers are off. Neither would not go above their no load limit. Perhaps the European cars are programed a bit different than ours and it is set to shut down when no load gets too high.

Could it be that the LIMP mode is active? Just a thought.

 

Here in the USA, with the last two Crossfires I've had, if you pressed the pedal to the floor in Neutral, the engine sits at 4100 rpm. I would think yours is the same. If the CAT is blocked, I'd expect the engine to vary in speed, not sit at 2500.

Now, the PTCM runs the engine based largely on the CAM and CRANK sensors, they tell the PTCM what position the crank and cam are in at any particular time - so it knows when to fire injectors and plugs. I suppose if there is a slight variation in the phase/timing one of them is producing, the PTCM would get confused. If I had this issue, and easy stuff did not resolve this, I'd replace in the following order:

Crank Sensor
Cam Sensor
MAF
Throttle Body....
... with a thought that a clogged cat can cause issues. But on the OTHER hand, when the engine approaches. 2500, what does a live data reader show as to:

Timing advance
Throttle position

As the engine speeds up, the timing has to advance a little so the detonation happens in time to help push the piston down, if it does not advance enough, power is lost. Could a sensor be causing the PTCM to alter timing such that 2500 is the limit? No "code" is going to tell you this, the person working on it has to have a good understanding of how the engine works and how timing, fuel mixture, etc. work together. But a sensor going nuts can cause all sorts of odd issues.

Just my thougths....

 

With the code P0335 should be freeze frame data, but the OP doesn't seem to have that info.