ibbo14

Hi MB Experts,

I am having a problem which is driving me up the wall.

About a month ago I started having throttle issues where randomly I would experience very poor acceleration. The car would struggle to get past 2000 RPM. Restarting the engine temporally fixed it, but the problem would return shortly.

I managed to hook the car up to DAS and I kept getting p0120 (Throttle Valve Actuator).

So this is what I have done so far:

Replaced TPS sensor while engine was running to rule out TPS failure, problem remained.

Removed and Cleaned Throttle Body - Was ok for one day then back to the same issue.

Reset adaptations - Same issue

Replaced Throttle body from an S430, but could not even start engine. I could not even reset the adaptation with engine running. So I pulled it out, and then noticed that the hose connector which sits on the breather hole is brittle and broken. So I replaced it and reset the adaptations on the original throttle body and it was OK for one week now.

The symptom is slightly different now. The car will accelerate past 2500 rpm, but there is still a significant lag.

I checked all vacuum hoses and connectors, but nothing obvious. P0120 still comes up as the only code.

I've checked voltages and values off DAS and it all seems to be good. I was speculating a bad wiring harness, but they all look good. I am stumped at what this could be.

Any suggestions or advice would be greatly appreciated.

Thanks!

MarcusF

If what you're saying is - step on the gas and there is a huge delay, I had that problem last June. Car lost power on a trip from the airport, so I took it to the dealer. They diagnosed and repaired the car in under two hours. No appointment, I roll in at 2 in the afternoon and left with the car fixed at 4 PM. The official MB part description was a throttle pedal travel sensor. It's part number 012-542-33-17 and cost $235.20. Labor was $210. MB of Annapolis (Internet parts dealer) has them for $171, so the markup really wasn't bad.

Aussiesuede

Yep, sounds like the accelerator Pedal Sensor is failing:


FCP Groton is an excellent source for Euro Parts: ($198 Shipped and easily replaced. Just two bolts and a simple plugin)

https://www.fcpeuro.com/products/mer...sor-0125423317

Same part number as referenced above. It's a common part failure.

ibbo14

Thanks MarcusF & Aussiesuede for the reply,

Ok, sounds like DAS was pointing me in the wrong direction. I would have thought it would have thrown a TPS equivalent code. I did initially suspect the TPS. I did pull the same part out of an e350. Same part number, but the cable mount was different.

So I think I went wrong by diagnosing this when the symptom reappeared and did the simple swap test while the engine was running. It didn't make a difference, but now I am thinking that since the engine required restarting since it has entered into it's "mini limp" mode.

Or could it be that the spare was a dud too?

Thanks for the link. It's much cheaper than what the stealer-ship is asking in Australia. You won't believe me if I tell you this but MB Australia is asking $2900! By the way, does it come as a single part as shown on the image? Or is the cable mount a separate part?

Thanks!

FCPEuro

Aussiesuede, thanks for the kind words.

The part will come exactly as pictured however it would not be a problem to source the cable mount if you needed it. In addition to the above link, I carry the Hella branded part at this link

--Kyle

ibbo14

Thank you very much!

I'll place an order shortly and go from there. I just checked out your site Kyle and your prices are great. I'm gonna order another few parts from you too.

I'll let you know of the outcome.

Thanks again!

oscaar12

I have a similar issue. My 03 CLK430 77.000 miles. runs great until I floor it or need the passing gear to get by some one .It goes into limp mode and has no power, no codes, but comes back to life if I shut it off and start again. I suspect it is the same as the thread is explaining. ???
Thanks

ibbo14

Same problem tqracn, but I do get a code though. Mine seems to haunt me when I am at a standstill at an intersection.

However this morning I did have a new symptom emerge. When I started the engine, the revs were going up and down erratically and I got an EBS/ABS warning on the dash. After a couple of restarts it stabilized. I'll replace the TPS, but something is telling me there could be more to the story, perhaps a bad lambda sensor.

ibbo14

Hi Experts,
Sorry for the late post, but here’s an update with this issue:
I have replaced the TPS with a new one, and it behaved for a few days and the issue reappeared again. This time with a new symptom, where revs are stuck when I rev in P or Neutral. Also when the fault appears while driving, when I come to a full stop my engine stalls.


I have been told the new TPS is faulty too. So I have replaced it again with a new one, and the problem disappeared after a few days and appeared again.


I keep getting the sample fault code p0120. It can’t be that all these replacement sensors are faulty.
Just to clear my doubts, I have replaced the MAF and checked for any vacuum leaks, but cannot find any.

At this point I am out of Ideas. Could this be an ECU problem?

jonUF02

Try replacing the throttle body, then clearing the engine adaptations. It's electronic, basically the other half of the pedal sensor you replaced. I think I have a couple extra used throttle bodies for the 430 I could sell. I've replaced mine from a junked E430 when having idle issues and it worked fine, but I had to reset the adaptations (via computer).


For the cut out when gas is floored issue, I've heard similar issues from broken up Cats that get clogged and cause the car to stall out on hard acceleration.

Aussiesuede

1st, when you replaced the accelerator pedal sensor, did you carefully inspect the inside of the plug to make sure it was both free of any 'green' dusty buildup, and that the actual wiring to the plug was still firmly seated in the connector? Some times people will grab the wiring itself in and effort to unplug, instead of tugging on the connector itself. Sometimes this can cause the actual wire terminal inside the connector to dislodge.

Before trying to test the ECU, I'd first have a look at the CAMSHAFT position sensor. I''' restate that for clarity - the CAMSHAFT position sensor. NOT the crankshaft position sensor.

The engine stalling when coming to a stop is the #1 symptom of a failing CAMSHAFT position sensor. FCP carries the Camshaft position sensor as well, but before throwing more parts at the problem, take a look at that connector to rule that out.

ibbo14

Hi All,

I forgot to update this thread.

I have managed to fix this problem and it was a few things.

The throttle body had an issue as it was starting to get very noisy. The replacement TPS did not resolve the issue directly. The replacement TPS did become faulty. So I am suspecting the damaged throttle body probably damaged the replacement TPS.

So, I replaced the throttle body from a c430 and the TPS with a brand new one, and then reset the adaptation for the throttle body.

Problem has been fixed and has not returned.

Thanks for all your input and help!