Puzzle with CLS 320

[gliggsy]

Hi guys, can't figure up what is happening, the problem is, when the car is cold it doesn't like being accelerated hard or even moderately hard and it will go in to limp mode.......... But the light doesn't come on and no messages, surely, if it is in limp then the light ought to be illuminated, switch off and start again,all is fine and not a problem when up to operating temperature. Any thoughts out there, the car is a diesel of course and I'm guessing it's going to be one of the sensors! But which one........g

 

[bembo449]

a blocked EGR will not always bring the EML if the electronic part is working correctly so I'd start by cleaning the EGR as its cheap to do , a session on star would be the next step , it could also be the boost pressure controller on the turbo ( electronic wastegate) failing as my grand fathers S320 started doing similar and it was the culprit

 

[Wighty]

Is it a well serviced car that is playing up ?. What mileage has it got ?

 

[John Laidlaw]

EGR sounds a likely culprit, clear it then maybe some Forte treatment, as Bembo449 suggests, cheap try..
What kind of driving/mileage do you do?

 

[television]

very hard to clean these valves as the spring can go weak, some do get success, no warning lamp should mean the air intake and return from the return gas should be OK.

 

[gliggsy]

Thanks for the input guys,the car is 2007 with 85,000 miles, doesn't get many regular services, only had it 14 months and 3,000 miles, will have a look at the egr valve although its not a problem atm

 

[Wighty]

That's not a lot of mileage , I'm guessing a lot of short runs , which big diesels don't like . As said above , a decent fuel system cleaner combined with a good motorway run . And maybe a service with air/fuel filter ?
Good luck . The egr valve is easy to get off and clean on that engine .

 

[John Laidlaw]

^ what he said!

 

[Steve@Avantgarde]

It wont be the EGR, they are fully electronic and monitored by the engine ECU, opening to either 5 or 95% depending on throttle position. It cant jam half way. If the EGR fails it will limp.

Usually a turbo jam or exhaust back pressure sensor failing.

 

[rf065]

For a short time, mine went into limp with no codes or engine light, despite everyone saying that was impossible. Cut a long story short, the intercooler hose was cracked and after fitting a new hose it never went into limp again.

Russ

 

[gliggsy]

I always respect your opinion Steve, would guess that the sensor may be failing as otherwise the car is running perfectly, don't do a lot of mileage per annum but it's usually motorway and get on with it. I will monitor the situation and report......g

 

[KennyN]

For a short time, mine went into limp with no codes or engine light, despite everyone saying that was impossible.

Mine did the same , three LHM then the CEL . Diagnosed in seconds by Mobilo , in the works carpark, as a faulty pressure sensor somewhere on the inlet side of things.

Sensor replaced at dealer and fault never returned.

Get the stored codes read , its the only way to be sure.

Kenny

 

[gliggsy]

Ok, the latest on this... Car still having the same problem although it went to Florence and back in October with only one occurrence. Had a code reader on it last week and its coming up p2044 which is the exhaust temp sensor but I'm scratching my head with the engine management light not displaying, could the bulb have been removed, any thoughts guys....g

 

[LostKiwi]

Engine management light will come when ignition on then go off after engine starts.