Limp mode

[minyak]

Hi guys,

I am facing this weird problem. Just had the car in for servicing but now its behaving strangely. The problem is that at times, the engine will go into limp mode, i.e. would not rev beyond 3000rpm, sometimes this comes on after weird vibrations which affects the body, but NO electrical fault messages on the on-board computer.Its a C220 CDi (W203- with 100k+ miles).

The car has recently been serviced, turbo system checked, intercooler and radiator replaced due to cracks and all other things done during routine servicing. But limp mode comes in intermittently, at most other times the car runs fine, full power and all.....

So guys, what are other causes for this limp mode, fuel lines, exhausts...The thing is that it comes on randomly, if it were a physical/mechanical problem surely the car would not whizz effortlessly at other times...could it be some electrical bug, wiring flaw somewhere..??

Thanks,..

 

[Asif Kazani]

I had a similar problem on my E220 CDI. You need to have the inlet port shutoff motor checked. This is right below the inlet manifold, mounted on the underside. Quite tricky to get to but this motor operates valves, 4 in our case (one for each cylinder), to the air inlet, opening and closing them as and when needed in conjunction with the function of the EGR Valve. It has a tendency of dislocating the operating arm and thereby malfunctioning at times due to the stress thereby throwing the car in limp home mode This should however show up on Star Diagnosis. The other thing that I could think of would be the MAF. Did you get the pm I sent you regarding choked exhausts on these cars due to high sulpur diesel available in our region?? Could very well be this too!

Good Luck,

Asif.

 

[Brian WH]

No good guessing and messing about, get the car put onto the Diagnostic computer, that will tell them exactly what is happening. Could be something or nothing, just wait and see.

Book it in NOW mate.

 

[minyak]

Ok thanks for this guys. After a word with the service consultant, he's just ask to see how the car goes a few days and then decide from there.

With regards to high sulphur fuel, yes my country has higher levels compared to UK. However, unofficial (but credible) word within industry suggests that the levels are approaching Euro 2 (will be mandatory real soon) which indicates <500ppm. Even before this, samples of fuel survey has indicated that there are brands here which are better than this figure, though still not quite Euro3 or 4.

Advices for CDi users here would be to occasionally 'blast' the car down motorways to flush out all those mucks that may potentially jam the cat, using good C(F-I plus) grade diesel fully synthetic engine oil (using CI grade at the moment), and changing the fuel and oil filters earlier than the on-board computer suggest (6 months or 10000 km).

I hope the current problem is a minor electrical glitch and nothing more...will update later...cheers..

 

[minyak]

Ok update here.

Took the car to the service centre and had the expert to check on those random limp home mode occurence. Nothing showed up wrong the the diagnostics and he had checked the motor under the manifold as well...nothing wrong there...exhaust was also fine...what he did was just clean those induction hoses (that also connects the MAS sensor), and he did find that one of the related tubes had a little broken part to it which he did a quick fix....did some cleaning here and there too....Then we took the car for a spin and whoila all was well.....no more darn vibrations or limp modes and he was impressed with the car's smoothness for a 4cylinder turbodiesel I told him it's a tuned car which gave power outputs higher than the average 220CDi and hence was better to drive and surprisingly did not smoke that much .....over the last two days I had travelled a bit and drove about 650km or so and it went like a peach....took it up to 186km/hr on few occasions and it whizzed efforlessly...drinking diesel at around 5.7l/100km (at 118km/hr travel speed) which is great i think with 3 adults and 2 yr kid with some luggage in the estate boot.....so i think all along it must have been some loose ends or dirt somewhere messing around with the electrical signals....
So in view of using higher sulphur content diesel available in this country (up to 1000ppm) I would advocate the following which I am practicing on my car:

-) frequently blast the car to un'choke' the cat and exhaust system
-) use fully synthetic engine oil, am using Mobil 1 Delvac grade C-I now
-) use injector cleaners, STP or the like
-) change oil and oil filter at 10,000km or 6 months intervals