akbro93704

This may sound like a weird question, but do the 1.8l C230 kompressors have the normal high RPM idle after a cold start??

c230K415

Yeah they do...and mine usually drops within 5 minutes or less.

Kristen

I'm getting the same problem.

Idle will be at ~1500 and fall to ~900 after about a minute, and ~700 after 5 mins.

If you check the fuel mileage screen, it'll indicate very bad fuel mileage (~20 L/100kms, or ~15 mpg) and that will change to normal levels within 20 mins of driving. If you wait 5 mins till the idle is normal, then reset the fuel mileage screen, it'll indicate normal fuel mileage.

Some notes:
- I had this problem before the new engine was installed.
- The problem persists on the new engine.
- The wiring harness, ECU, and all sensors were transfered to the new engine.
- There is a TSB for a cold start idle problem (P_07_61-037A) on the M271, since I'm in Canada I suspect my dealer will have no clue about this.

jedcred

This may not be a "problem," per se, at least not the way it's being described. All cars have high idles from cold start; it is meant to quickly heat up the engine and related parts, including the catalytic converter. Living in California means that the usual morning temperature is about 50-60 F, and I still get this kind of thing, but for a shorter period of time than people who live in Canada, say, might.

Also, the fuel mileage screen for the first five minutes cannot possibly be correct in any context. For instance, if all things were equal, your mileage should read zero, since (0 miles)/(fuel used) is zero. Thus MB has decided to fudge the numbers a bit (probably starting you off at 1 mile, for instance) so as not to start off at zero, otherwise upsetting the fragile balance of their fuel-conscious customers . Usually when mine starts it goes from 28 or so all the way down to 20. If I don't move the car (and I rarely ever let the car sit at idle for cold starts) it will continue to drop until it hits 15ish.

Unless you're having some other severe problem (say, RPMs over 2500) or rough starts (could need a different viscosity oil in colder weather), I say you're fine.

C230 Sport Coup

Kristen,
You went with a new engine? Wow.
As opposed to just the head eh?

Most cars are set to run rich till they are hot.
I have the same problem with mileage until the engine is hot.

Around town, close to home errands result in about 15 mpg, and thats driving gentle.
Getting the highest mileage requires a longer trip.

Kristen

Thanks, that's what I wanted to confirm. I've had so many problems with this car over the past 2 years I don't remember what is normal anymore.

My screen starts at ~10L/100km (~30mpg) and quickly increases > 20L/100km (< 15 mpg) before setting back at 9-11L/100km by the time I'm at work.

Kristen

Hole in piston #3, it wore through on the side, the wall is scored. I have the block in my garage, going to pull the piston and see what happened, maybe a ring snapped?

A used low-mileage engine and low-mileage primary cat/exhaust manifold were installed. I had the vacuum lines, cam sensors, and isolation wires all installed on the used engine before it was installed.

I'm hoping to get another 2-3 years out of this car as I save up to buy something else. I enjoy driving it, and now have an entire engine of spare parts (TB, SC, cylinder head, intake manifold, vacuum lines, engine harness, all sensors, injectors, ... ).

I have all the parts from that engine listed for sale in the classifieds.

JonathanMax