limp mode

[max411]

Hi, my sprinter goes into limp mode, sometimes it stays in limp, other times it fixes itself while driving, I noticed a wet patch under it after I stopped driving ,
I had to top up coolant, 2007 313 cdi, had a code test done but as it was not in limp, nothing showed up, My first ever merc!
Where do I start?, I might add I know sod all about engines,( thats why I ended up with this one I think!)

 

[LostKiwi]

With no codes anything we suggest will be pure guesswork.

Even with the light out it should keep the error as a stored code.

You may need an MB specific code reader to see it.

 

[max411]

Hi, thanks for reply, would the leak cause limp mode? my guess it would, but i know nothing about these things

 

[LostKiwi]

I'd be guessing as we don't know what the leak is or where it's from.

 

[supernoodle]

I'm guessing it's not a limp mode or enforced restricted performance if there are no codes or MIL.
It's quite possible something is failing (or is getting wet if you have a leak) and giving a bad reading that is in range which would give a torque limitation.

First off detemine of you really have got a leak, fix that if so and take it from there.

 

[max411]

Hi, thanks for reply, i can see droplets around bottom of pulleys, perhaps water pump but that could be running from anywhere!
my mechanic is off with a slipped disc so cannot get him to look at it, just hoping its not anything major, as its my work van, just got it 4 weeks ago,
bugging me every time i look at it, have to go for a 60 mile round trip tomorrow will see what happens,
oh, can limp mode shut van down & go leave me at the side of road?

 

[LostKiwi]

Generally no. Limp is exactly that - a get you home while protecting the engine mode.

 

[max411]

getting it booked in next week, at a quick glance the mech, said looks like water pump but would need to do pressure checks, for other leaks.
so hoping not anything more than that, fingers crossed,

 

[max411]

van in today, will post results later

 

[max411]

Hi guys, van still going into limp mode, 20 times on sunday, in a 25 mile trip, got water pump done, no more leaks, code showed faulty crankshaft sensor, done that, code showing turbo under boost, any ideas, just about sick of it, have to clutch switch off engine switch back on again to reboot com,
cheers

 

[rf065]

I'm guessing it's not a limp mode or enforced restricted performance if there are no codes or MIL.

You could not be more wrong, my CLK went into limp mode countless times over a two year period without the EML going on. Everytime I took it to Mercedes they said there were no fault codes and could not find any problem. Eventually, this occurred more and more frequently until one day the EML light came on and then Mercedes found a fault code and fixed it. For two years I had forum members telling me limp mode could not happen without a fault code, but it can.

 

[supernoodle]

You could not be more wrong, my CLK went into limp mode countless times over a two year period without the EML going on. Everytime I took it to Mercedes they said there were no fault codes and could not find any problem. Eventually, this occurred more and more frequently until one day the EML light came on and then Mercedes found a fault code and fixed it. For two years I had forum members telling me limp mode could not happen without a fault code, but it can.

That is exactly the point. You may get some failure mode that isn't necessarily detected as a fault, but to you the driver the symptom is lack of power.

As an example, if your fuel temperature sensor were to go wrong and report a temp of 70 degrees when it wasn't, the ECU would quite correctly cause a derate (it derates to and reduce temps). As 70 degrees could well be seen with low fuel levels and high loads it won't necessarily flag a fault.

Limp home mode (restricted performance) is a reaction to a fault. The failure that is causing the fault may not cause a derate itself, but one of intentional reactions may be to restrict performance to mitigate the damage.

So to you the driver you may notice a lack of power, but it is not limp home mode (restricted performance) unless there is fault.

 

[ajlsl600]

G

Hi guys, van still going into limp mode, 20 times on sunday, in a 25 mile trip, got water pump done, no more leaks, code showed faulty crankshaft sensor, done that, code showing turbo under boost, any ideas, just about sick of it, have to clutch switch off engine switch back on again to reboot com,
cheers

Get yrself icarsoft mb v2 and drive it around plugged in see wot pops up as goes into limp. Crazy but that's modern shite 4 u. Today it's either a headache or wallet drainer, sometimes both
Generally if it brings no code I find it to be harness related. Which can be a buxxer to locate and due to dealer rates it just an open ended deal in their favour., also can be a loose wire, connection. Home testing of some sensors often not easy as the type or rtn signal is not always straight forward. If its ur work vehicle ur prob best solution. Is a known indy in ur area, after you recheck all the basics that you can.

 

[rf065]

That is exactly the point. You may get some failure mode that isn't necessarily detected as a fault, but to you the driver the symptom is lack of power.

As an example, if your fuel temperature sensor were to go wrong and report a temp of 70 degrees when it wasn't, the ECU would quite correctly cause a derate (it derates to and reduce temps). As 70 degrees could well be seen with low fuel levels and high loads it won't necessarily flag a fault.

Limp home mode (restricted performance) is a reaction to a fault. The failure that is causing the fault may not cause a derate itself, but one of intentional reactions may be to restrict performance to mitigate the damage.

So to you the driver you may notice a lack of power, but it is not limp home mode (restricted performance) unless there is fault.

I can assure you I know what limp mode is and how it feels, My CLK went into limp dozens of times with no code. Every time I only had to switch it off and restart and it behaved normally until the next time it happened.

 

[max411]

Hi I notice a strong exhaust gas smell outside van, not inside, could there be something there causing limp?

 

[Blobcat]

Hi I notice a strong exhaust gas smell outside van, not inside, could there be something there causing limp?

That sounds (smells…) like the DPF doing a regen (assuming you have one).

My VW Caravelle used to do it at lights or fuel stations, got used to it over time

 

[ajlsl600]

I can assure you I know what limp mode is and how it feels, My CLK went into limp dozens of times with no code. Every time I only had to switch it off and restart and it behaved normally until the next time it happened.

Had same on my clk when on. . Motorways or duel carriage ways at speed cornering. Turned out a little to much oil in. Lowered it a lt stopped happening. Temp solution was pull over. Turn off, on and moderate cornering speed took a while to work out wot was going on.

 

[Kev555]

Limp mode could be caused by any number of things, Your DPF could be overfilled, some of your boost pipes could be leaking, faulty injectors, leaking inlet manifold or swirls flaps, if they all apply to your engine that is. You wont know until you plug it in to diagnostics and if theres no codes you'll just have to look at live Data + fill level of DPF etc

 

[tpn]

When you buy a used Mercedes you should immediately buy, at least, an Icarsoft diagnostics...better still buy it beforehand and check out your potential purchase with it.
Without codes everything is conjecture; even with codes there is still some guesswork.

It is not good to be driving around with codes, as your vehicle will not do a regen when there is a code present.
Also do not go below 25% fuel in the fuel tank for the same reason.

 

[ajlsl600]

None of which the f, s tell u when u hand over ur cash. I think icarsoft shud be intrigated with command. Some clever f do that can make some cash I sure. Ignition on run code check, save, start fix on w ends instead of waitin on recovery. Get my vote 4 sure.