C230K M111.975 Won't Accelerate over 4500RPM

[sicelo]

After ECU adaptations were reset using Carsoft on my car (which was an unintended mistake), it no longer can accelerate over 4500rpm while driving. In case it helps, the car has manual transmission. It was just fine shortly before ECU adaptations were reset.

Car is still driveable, and has all the expected power up to that 4500rpm limit.

At 4000-4500rpm, the car feels/sounds the same way it does when you rev to that point at idle, as if something is specifically limiting it.

I'll be getting a generic OBD reader by the weekend, and hopefully that will shed some more light into the matter. I have a pal with Bosch KTS570 that I could see as well around the same time.

In the meantime, I would welcome any suggestions. (Maybe throttle body? maf? but the strange thing is why would it have been working fine before the adaptation reset)

 

[John Jones Jr]

I'm not too sure what your problem is, won't rev past 4500 or you're losing power after 4500?

I suspect what might be happening is the S/charger is disengaging at 4000-4500 and stays disengaged until you switch the engine off and engages again until you hit 4-4500 rpm?

At a guess, I'd say you've got a faulty MAF. The first thing to do is get the fault codes this will give you an indication of what the problem is.

 

[sicelo]

Will report back on weekend or next week with codes. S/C seems working normal as I can hear it engage and disengage in the correct ranges without ever switching off. I could rev. to red-line by putting it in neutral while coasting, but when a gear is engaged, it just feels like rev. limiter is active. So the problem is related to "load" and I wouldn't discount a MAF problem. Just weird that there was absolutely no problem before adaptation reset, except a very slight idle hunt, which is still there.

 

[John Jones Jr]

Well, it takes 200-250 miles before the engine ECU carries out a full relearn. I'm not saying that's the issue but worth bearing in mind if nothing else.

 

[John Jones Jr]

So the problem is related to "load" and I wouldn't discount a MAF problem.

The MAF supplies the load signal to the ECU, thus my comment about a faulty MAF. Keep us updated.

 

[Auto-mobile]

New air mass first, then if that doesn't make any difference clean the throttle body and carry out boot strapping.

 

[sicelo]

Thanks. What is boot strapping?

 

[sicelo]

In the meantime, my ELM327 arrived. However I had other commitments, but managed to hook it up for reading codes quickly. A P0170 is the active code (MAF again basically), and a P0130 pending code. Bad times ahead.

Happy about the ELM327, and thanks to John Jones Jr. for his help regarding OBD tool

 

[Auto-mobile]

Thanks. What is boot strapping?

Basically adaptations of the throttle body, should be listed as boot strapping for Mercedes.

 

[vijilants]

I have a copy of Carsoft 7.4 and have used it to do the reset on my previous C230K (1999) several times and also on other W202 models.

What initially happens is you have no throttle whatsoever, but after switching the engine on and off a few times this clears and the car should function properly.

It should definately be free to rev.

Have you cleared out all the fault codes ?

 

[sicelo]

@vijilants : I have a P0170 that won't really clear and is likely a sign of MAF failure.

got a chance to play with my OBD tool a few hours ago, and my MAP reading is a constant 133kPa regardless of what I may be doing (idle, accel). Just curious ... at this time I don't think that's a cause, although I do want to check this sensor as well now.

Another 'stuck' parameter is that of Long Term Fuel Trims, which is stuck at +32 (maybe the maximum it can go to? hence P0170?)

Here's a plot of the other sensors for about 2 minutes of idle time. When the scantool is better configured I will be able to log while driving

will be looking at replacement MAF, but currently don't have that kind of money. Great timing

 

[John Jones Jr]

There's no MAP on that engine only the MAF thus the constant and non changing MAP reading.

Would it not be the case that P0170 (possibly faulty MAF) is causing the LTFT to show lean, i.e. +32?

If it is the MAF that's at fault, do search on eBay.de for (a genuine Bosch and Pierburg) LUFTMASSENMESSER MERCEDES C-KLASSE W202. You should be able to find them in or around €70-90 and look for the MAF itself as usually they are more expensive with the Housing which is rarely needed.

Do check the MAF for oil contamination, if there's oil on it there's a possibility the PCV valve and/or the two breather jets (located under the inlet manifold) are blocked.

 

[flango]

MAF is currently under £100 at ecp if you use club discount code of MBCLUB25 which strangely worked on Thursday when I needed one

 

[sicelo]

Win!

Woah!
I was testing this 4500rpm phenomenon again today, and when it started surging, I just kept my foot down (killing the car?). MAF reading went very low at that instant (dead MAF?).

Then the unexpected happened .. revs went up to redline. From that moment I can now reach redline smoothly, and MAF no longer reads low while revving.

So I have my Kompressor back!!! Great day for me. :bannana:

Oh, the P0170 code is not there anymore. I'll keep an eye on that MAF though, until I'm satisfied all is well. My LTFT is still a constant 32, and doesn't even change by 1% at any moment. Starting to wonder if in my vehicle, LTFT via OBD is a bogus reading as well (like the MAP sensor). Mercedes, grrr.

 

[John Jones Jr]

Woah!


Oh, the P0170 code is not there anymore. I'll keep an eye on that MAF though, until I'm satisfied all is well. My LTFT is still a constant 32, and doesn't even change by 1% at any moment. Starting to wonder if in my vehicle, LTFT via OBD is a bogus reading as well (like the MAP sensor). Mercedes, grrr.

Good news on the MAF. It does seem a bit strange that it was a one off intermittent fault?

The LTFT's should adjust now that the MAF is back operating, 32 is far too lean. You should drive the car and check to see if the trim falls. Ideally the LTFT should be within 10 +/- of the STFT. May be disconnect the battery for 20-30 mins and then allow 200-250 miles for the ECU to do a fully relearn.

 

[sicelo]

That 'victory' was only temporary, as the situation is back as it was before. After disconnecting MAF, performance restored. So I'm now looking for a MAF. I've reconnected my faulty one for the time being, as it is good enough for average driving.

 

[John Jones Jr]

That 'victory' was only temporary, as the situation is back as it was before. After disconnecting MAF, performance restored. So I'm now looking for a MAF. I've reconnected my faulty one for the time being, as it is good enough for average driving.

No surprise. Anyway, you know the problem for sure now so you're winning.

 

[sicelo]

by the way, yes, there is oil contamination, so I need to attack that first before putting in a new MAF.

I saw some threads suggesting to move the location of the MAF, and some suggesting that such relocation doesn't really help. What's the best way to avoid contamination of MAF?

 

[vijilants]

by the way, yes, there is oil contamination, so I need to attack that first before putting in a new MAF.

I saw some threads suggesting to move the location of the MAF, and some suggesting that such relocation doesn't really help. What's the best way to avoid contamination of MAF?

Here is a really good thread on how to do the job to stop oil contamination in the MAF.

Rearding the MAF relocate, I did it and it smoothed out the acceleration.

I have a pdf somewhere on how to do it and parts required.

 

[sicelo]

Here is a really good thread on how to do the job to stop oil contamination in the MAF..

you forgot to include a link, I suppose

As for relocation, I don't think I'll do it. This is where I read, Factory BOSCH MAF vs Pierburg test - Mercedes-Benz Forum

As long as I stop oil reaching MAF, I'll be good