dmatre

OK. I've just returned from a quick trip to the mall, and have encountered the first 'real' problem with the C (91k, so I guess I've been lucky so far).

As I was leaving the mall, I was in the left lane, and needed to exit right about 1/8 mile ahead, so I carpeted the throttle, and . . . nothing. I couldn't pass the old lady in the Malibu next to me.

I had to abort the freeway entrance, so I went to the next light scratching my head & wondering why there was no acceleration. Well, the light went green, and I was easily able to keep up with the (slow) flow of traffic. When traffic cleared, I carpeted the pedal again . . . and the car just barely accelerated.

Now I figure something's really wrong, but no warning lights are illuminated. So at the next light, I put the tranny into Neutral & mat the pedal again - and the engine revs very slowly (as if I've only tipped into the throttle 1/4-inch).

So now I figure I'm minutes away from a tow. So I pulled into a parking lot to get out of traffic, and flip down the visor to find the 800-number for the 'friendly' MB mobile service. I figure before calling MB for a tow, I'd try shutting off/restarting the car, just to see if it went away (hey - sometimes I get lucky).

Upon restart: everything's back to normal.

So now the questions:
1) Has this happened to anyone else?
2) From where I was sitting, it seemed to be an issue of the throttle position sensor, rather than the transmission or engine control (because it also occurred in neutral, and there was no misfire, or CEL). Sound plausible?
3) Live with it 'till it occurs again, or change it out now?

Thanks in advance, for anyone with any info on this one!

BabyBenz6spd

If I were you I'll probably try the "throttle Reset Procedure" (If you don't know how to do it, try searching the form), drive it around for a day or two, and see if the problem comes back. If it does, then probably making a trip to the dealer maybe required.

But of course dealers are best to be avoided if possible, $$$~

DarthBudice

I had a very similar problem - stomp the throttle and absolutely nothing
for 3 - 5 seconds.

Mine was a simple vacuum leak I fixed with a 10 cent hose clamp.
I suspect it cleared up when the engine was restarted due to clearing
the short term fuel trims. All the un-metered air entering the intake
was causing the ME to constantly adjust fuel trims because the O2
sensors kept reporting lean condition (extra air with no extra fuel).

I have one of the OBD-II interfaces from o b d diagnostics . com -
I see after clamping that hose down my short term trims are always at 0 now...

FYI I haven't had to use the throttle reset in 4 months or so now...

mig888

dmatre, yes. TPS does go bad...I've done a replacement twice (once on mine and another vehicle). Get it replaced, because man it sucks to go around without juice :\. In the meantime, I had a problem in conjunction with my spark plugs, so I changed those the same time.

Marky Bends

My car is doing that same thing right now. I brought it in to the dealer because of a battery drain (seat module..what else) and told them about this problem too.

They told me a simple software update would fix it. I went to pick up my car, drove it off the lot, circled the block and drove it back. Check engine light went on and the same 3 second throttle lag present..same thing. I wonder if they test drive them? $120/hr for this?

Yeesh, now I have to drive a B class..bleh..

tanktube67

maybe a glitch

Remy_B

I am experiencing a very similar problem. I was 90% sure it was due to a bad TPS until i read this thread... it just reminded me that i had some vacuum leaks recently... and i just pushed some piping back in to fix it.

1-Does someone knows if it's possible to clean/fix the TPS sensor or does it needs to be replaced?
2- Does someone has a drawing of the whole vacuum circuit so i could follow the pipes and look for leak or weak connection? Is there some know weak point on the vacuum system that i should inspect first?

Thanks!

I'll copy below the thread I posted on a diffrent forum in case it would help someone helping me. BTW... sorry for the strange grammmar... english is not my first language!
___________________________

Good day everyone!

Ok… I was totally angry because of all the problems I had with my C230 Kompressor 2002…. So I decided to sell it, just after a nice and expensive maintenance B. Unfortunately, half way between the dealer and my place, a new issue appeared (again), making that car impossible to sell. Ok, I have to admit, the dealer is 1200km away from my place, including 500km of dirt road; but still… it’s frustrating.

I found some threads describing issues similar to the one I had… but since I am not 100% confident it’s same issue, I decided to keep this one separate.

Here is the issue:
When depressing the throttle pedal, the engine is responding very slowly - delayed. (It does nothing at first, and starts to rev faster if I keep the pedal depressed for a while.)

I did stupid and floored it until I hit the end of travel limit switch pedal and I got the OBD2 trouble code #P0121 (Throttle/Pedal Position Sensor/Switch "A" Circuit Range/Performance)

The pedal seems to send the proper message to the engine; if I depress it very slowly… the engine very slowly picks up speed… which makes me to believe that the sensor “in the pedal” is fine.

I talked to the dealer, and he suggested me to clean the mass air flow sensor. (Apparently some oil tends to accumulate in there.) I told the mechanic I had doubts about the MAF sensor theory since the idling is relatively smooth; the problem only exists when trying to accelerate. I have to admit that he was not really willing to give me advices over the phone and insisted that I go back to them to get the issue fixed… but I am not really happy with the idea of driving an extra 2400km, and missing 2 days of work to go back to them, especially just after a service.

Now, the real questions are:
A) According to you experts, is it due to the MAF, the TPS or something else?
B) If it’s the TPS, is there a way to open and clean it/fix it, or will I have to buy a new and very expensive unit from the dealer?
C) How do I clean the MAF (where is it located).
D) Do you know a good online supplier for those parts?

Thanks for the help, it’s greatly appreciated!

Glyn M Ruck

dmatre - this can be nothing but brief TCU brain fade - happens now and again - car went into limp mode. Restart rebooted the processor.

You are auto - Yes? Check fluid level.

Then just watch it. If you have not thrown a TPS code it's unlikely the TPS - Don't go changing things - do a throttle reset.

Glyn M Ruck

Being so far away - people are going to be reluctant to help in case they are wrong but here goes: Please understand that this is an educated guess from the details you have provided - not being hands on makes this difficult & I could be wrong.

- Regarding the MAF on the M111 - See diagram below for location. MAF is item 1 - pipework routing varies from model to model but the basic layout is the same. I doubt that it is the MAF but cleaning it will do no harm. You will require an aerosol can of MAF cleaner. The best way to check MAF operation is to unplug it. This will force the ECU onto a default map - It is quite safe to unplug the MAF & drive the car - mixture control will not be perfect but if the engine runs normally with it unplugged you know the problem lies with the MAF. This will throw a MAF code which you will have to cancel with your OBDII scanner. I'm presuming you have access to a scanner - if not buy one from Kragens/PartsAmerica for $50



- clean the throttle body as well - see diagram

- Check all vacuum lines for leaks

- I'm afraid it does sound as though the TPS has come to the end of it's life. - Do a throttle reset to make sure but if the TPS is failing then in my experience, the only way is to replace it.

- C230 Sports Coup uses a place in Florida for good online spares prices. PM him or check his posts.

Good luck & don't hesitate to ask questions





I will look for a vacuum diagram for you & post

Glyn M Ruck

Vacuum circuit diagrams: There are various ones with minor differences for the M111 - I've only blown one up - open the rest by clicking below.

drastic

had the same thing happen on my wagon a few times. every time it happended i was on stop and go traffic. shut it off and waited a few minutes and ran fine after. i was told its a glitch on these cars when too many stop and go's heppen. meaning playing with the pedals. i did it once at home just to verify it and sure enough thats what happened. im still having a hard time believing thats the case tho. theres gotta be something else. as i read this topic, i will be checking my vacum lines.

Remy_B

Thank you for your help Glyn!

Where did you get all those diagrams by the way, are you a MB tech, or did you buy the DVD?

I was looking for one, but getting it delivered in canada ended up more complicated than i first thought! Yeah... one would think it's only a matter of putting it in an enveloppe... but apparently not that easy!

I am not a very good mechanic... but i hate going to the dealer and watch them throwing parts at a problem when a 10 cent hose clamp could do the trick. Beside, i find learning stuff about my car quite entertaining.

So... i'll follow the vacuum pipe, watch for loose stuff and clean the MAF and see what happens.

Oh... and i'd like to try the throttle reset thing as well. I've searched the forums and found about 15 different ways to do it... none seems to work. I think the most common one posted here is for 2003 and up vehicle, or for the automatic transmission only. In all case... it did not work at all for my car. (Standard 6sp, 2.3l, 2002, C230 coupé)

Thanks again for your help! Greatly appreciated!

Remy_B

Oh... and for the OBD2 reader, i have the carchip pro. It is nice because it has built in memory and allows to record some OBD2 parameters (4 at a time) while driving.

dmatre

Update (since original thread is > 1 year old):

At the next service (wiring harness replacement due to oil from cam sensors) I reported the problem to the dealer, and they replaced the TPS. Problem never reoccurred.

Remy_B

Maybe the vaccum hose connecting to the TPS was loose... who knows.

And just in case it's really the TPS... how much was the part? :S

Glyn M Ruck

Sorry d - I've done it again. I missed the date

dmatre

No problem at all. You've been a help to many here!

Glyn M Ruck

I'm a retired oilco man - see my profile. I have hundreds of Benz diagrams on my computer - mainly from MBSA. Filing system sucks. PM C230SportCoup for reset. He has the same car. How do you know the reset did not work?

Remy_B

Well... i dont know if the reset worked or not. I did'nt noticed any change... so i just assumed it did'nt.

I tried something today... i disassamble the throttle body, cleared the potentioneter tracks (of what i thought was called the throttle position sensor), and put it back together. It did not help.

While trying to follow the vacuum lines, I also noticed that there is a second part exactly similar at the front (passenger side). Not sure if it has the same purpose. Maybe that's the faulty one.

I just feel like i'm trying random stuff now... can't be good.

Day after day... it's getting worse. I'm just worried that when i have an opportunity to drive it back south, it wont be able to make it to the dealer.

Here are some pictures of what i disassambled:

C230 Sport Coup

TPS is a 'hall effect' sensor. You can test it with a simple voltmeter at specified
pins on the ECU or SAM.
It's in the service DVD. I'll look for it later.
Actually search on that stupid sprint booster thread I posted all the docs there.
Start at post 423. I got ripped by these idiots for good info.\
https://mbworld.org/forums/c-class-w...ml#post2161186

Remy_B

Ok... time for the dumb question of the day (I'll blame it on my french)...

Is the Throttle Position sensor :
a) the potentiometer that measures the opening of the throttle body.
b) the sensor that measures the position of the gaz pedal
c) none of the above.

Btw... that spring booster thread is something!

C230 Sport Coup

I thought you were speaking of the actual gas pedal on the floor.
The pics you posted are of the 'throttle body'.
Dude, you're from Labrador and you drive a C?
Woa.
I was at Church hill falls Hydro once, worked on some computer stuff there....
damn was it cold.
I learned how to 'curl' though while I was there.
2 days of flying from California.

Remy_B

To be perfectly honest... i have no clue what i'm talking about!

I explained the symtoms... and it matches with the "broken TPS issue" everywhere. So... i'm trying to fix a TPS without knowing exactly what it is!

Well... i still dont know what the issue is... but i have some very good ideas on what it is not.

Oh... and my error code is not P0120, but P0121... does the magic DVD says somthing about it?

And that gas pedal is a very bad design for cold weather; the lower flexible part gets frozen... and the whole assembly acts as a toggle... so if you depress the pedal, it gets stuck that way, and I often have to reach it with my hands to pull it back. Germans should visit cold countries from time to time.

Remy_B

Yeah... i drive a C in Labrador!

The G Wagons are too expensive! Beside, the dirt part of road 389 north are amazing with a rear wheel drive! Some very nice drifting opportunities. Only drawback... if something goes wrong... the ambulance is 8 hours away

I pay 60$ a year for road side assistance... just in case. Yes... they would really tow from Labrador City to the closest dealer!

Any jobs for an automation engineer in california? Do you still have snow there? :P

Glyn M Ruck

Todd, Thanks for helping - You know the Coupe like the back of your hand. Due to location this man really needs our help.

Let's transfer these across: