Hi All,

This is my first post and believe me before i have posted this i have trawled every forum on the net to get to the bottom of my issue which seems to be enormously common, however ... a million different ways it was supposedly solved.

The Issue i have is similar to every W208 owner over time i get power loss in the car where it will not kick back down the gears and accelerates like it is almost in (W) mode, it is most noticeable at 3000-3500rpm then launches back after that all the way to red line. Typical i do not get any CEL codes.

After reading everyone's take on it i am hoping that someone can help me pin point it and save me the hassle of Private messaging the guys who have solved it.

The most obvious suspect here is the MAF which i have replaced and it did not correct the problem, however the odd part that has got me stumped is if i do an ECU reset (disconnect the battery) the Car goes back to normal and runs like a bull for 2-3 months and then slowly looses its power again, which if you just cruise around town you would hardly notice, fuel economy and running is normal just wont get up and go like it should.

Saying that, and looking at everyone elses ("fixes") Fuel Filter, Intake Manifold clean, TB clean etc doesn't add up to me in this case as i would think they would be permanent issues and not ECU reset fixable .. (temporary

I am leaning towards something the engine adaptations are telling the ECU over time however not willing to just start throwing 02 sensors, TPS sensors at it unless i can nail it, parts in Australia are crazy compared to the rest of the world.

Sorry to flog the dead horse, i just cant seem to get a spot on answer or find anyone that ECU resetting solves it .. for a decent period of time.

Something in the system is teaching my ECU bad habits over time just need to find out who is the guilty party ...

HELP !
Shannon

 

Next time try just doing the reset for transmission adaptations. It's a procedure with the ignition and gas pedal, you can look it up. It's probably learning a particular driving style for your normal daily driving, then when you want to push it you don't like the way it's shifting. If you have the manual shift option, then try that and see if you still feel like the engine is bogging, or it's just the shift points. I was considering the Sprintbooster device because I don't like how quickly it up-shifts, like if you turn left from a stop light (or right in your country?) by the time you want to push the gas after the turn, it has already shifted into too high of a gear, so it takes a second to think about down-shift again before you can take off. Another scenario would be when I'm on the brakes to go around a corner, then I want to punch it again, it takes a while to pick the right gear. That's where the manual shifting comes into play.

 

Hey Jon,

Thanks for taking the time to read and give some advice, I should of mentioned this in the initial post, it makes no difference if i am in manual or auto mode, if i hold it in 1st or 2nd gear it will still hesitate between 3000-3500 and feel like it is lacking power (fuel in my mind).

I am almost convinced that it is trimming the fuel tables incorrectly and leaning the car out at that point or through the revs for some reason, then when we reset the ECU it goes back to its factory Fuel Trim Table which it runs fine, over time the autotune process seems to send it the wrong way,

The only things i can think of involved in that are, 1 MAF, 2 02 Sensors, 3 OAT (Outside Air Temp) is there something else ?

Is there some way to download the fuel trim tables from the Fuel Injection/ECU module ? would be easy to spot what happens from the ECU reset to the point where it goes back to weird performance.

 

The only way to really access the computer systems is with the dealer STAR computer. I suggest giving them some $$ to diagnose it with the computers before you just waste money on random parts. Also, see my thread about cleaning out the intake manifold and all the work I did. That was more of a rough idle problem, but can't hurt if you want to get your hands dirty. If the MAF or 02 sensors (or cats) were bad, then you would definitely get lights/codes.

So does it just stumble in the mid range, then blast off again into upper RPM?

 

I am considering ordering a pedal position sensor/throttle position sensor.

http://www.benzworld.org/forums/w208...strange-2.html

seems like it solved this issue.

Please keep thread going if you solve problem or don't solve.

 

It could be, sounds reasonable if your symptoms are exactly the same as that thread, but you will be disappointed if you spend the money and time to replace the part with no change. I still think the money will be better spent on fancy computer diagnostics.

 

Hi Guys,

To answer your question Jon, yes after it gets over its struggle through 3000-3500rpmish it does blast off again. Even though it is making the revs it is still not pulling as hard. I might try and get a copy of CarSoft running and see what i can discover before and after.

I have considered the TPS however it doesnt quite fit the bill to me, if i had a dodgey TPS i think it would be there the entire time and not go away after a ECU reset ? I may be wrong ? After the reset even just off the line the thing pulls like a bull and is trying to wheel spin etc. Another thing to note is when it is bad if i hit the kickdown switch i assume this ignores the TPS and just goes for it ! and it still has the issue.

It is also incredibly noticeable cruising at 100Km/h, when it is good putting your foot slightly into it will usually kick it back a gear or two and fly all the way until you want to loose your license, when it is bad it wont kick back or if it does it is just sluggish.

I might do the Manifold one day Jon, yours come up well and i have read your post a million times trying to find something to help me . Myn actually idles beautiful ... for now.

I'll keep going on it until it is worked out.

P.S i have just read the other thread and i can understand that being a TPS given that slow inputs would work, in my case it makes no difference how quick or wide you open the throttle.
I have just ordered a multiplexer for CarSoft 7.4, which will show me live readings of my 02 sensors TPS etc so should be able to nail it ... hopefully

Thanks for your help so far though !

 

Have you removed and cleaned the throttle body? Watch the actuator move as someone pushes the pedal to make sure it is complete and smooth action? I have a couple extra throttle bodies that I could sell if you need one.

If it was slow or irregular inputs from TPS or an actuator issue in the TB, then I would expect that the butterfly moves erratically or indirectly at some point. Try turning the car on, then remove the intake, and watch the butterfly action in the TB as you move the throttle cable to the TPS under the hood.

 

Hi All,

Just a bit of an update, i purchased a multiplexer off ebay and Carsoft 7.4 which BTW is CRAP! the multiplexer doesn't work very well however the one and only thing it lets me see is the ME live data !

What i have noticed is out of my 4 02 sensors Bank 1 and 2 Sensor 1 values fluctuate rapidly once the car is started which tells me they are doing there job however #2 sensors stay around .520V on one side and .465V on the other. I took it for a drive the other day with the laptop running and after about 10 minutes of driving the #2 sensors started to work properly.

Question is ? Is this normal behavior ? Or should all 4 sensors be sending information from the turn on point ? Or is this the CATS doing there job.

Any thoughts ?

 

Oh, yeah, I forgot to say that Carsoft is junk. I played with that setup before, and it is nothing like the dealer system. The only thing it did for me was allowed me to easily reset the engine adaptations without unhooking the battery. It may be able to read errors within the subsystems, but I didn't have any.

You can view the real-time data from the O2 sensors and other OBD2 systems with the free Torque app, and a $10 bluetooth OBD2 interface. It will graph and log the data.

What you are seeing on the O2 sensor readings seems normal. I'm not a mechanic, but I did a lot of research on this when having idle problems. The forward sensor readings will always fluctuate, spiking up and down, like a wave. The rear sensors will read fairly constant - after the cats have warmed up and can do their job. So you will see fluctuation in the rear sensnor readings until the cats are at the appropriate temperature to burn off the pollutants that are measured by the sensors.

If you see spikes in the rear O2 sensor readings, rather than a fairly flat line, after everything is nice and warm, then the cat on the offending bank is bad.

The secondary cats, after the second O2 sensor do nothing in relation to the computer. Unless you live in a state that tests emissions, then cut them out for a slightly sweeter exhaust note!

 

Hi. I have had the same problem with w208. I took it to dealership and they told me I needed to replace the engine and transmission mounts and put on new plugs and wires. I did what they said and I still have the same issue that you are having. I don't know if thus has anything to do with what our cars are doing but I did unhook the battery cable yesterday after installing a new MAF and the car had good power but would continue to cut off and the windows would not work properly. This all went away after about 10 minutes but unfortunately so did the power (HP). Could you please tell me what you did orhave done to resolve your issue? Thanks.

 

It sounds like your car is acting normally. When you disconnect the battery you have to go through the learning procedures with the windows and sunroof, you can look it up. The car will also need to re-learn the ABS sensors, as well as the engine and transmission adaptations.

The dealer basically found nothing, and told you to replace all the common "tune-up" parts, which never hurts. You could have done all that in your driveway for a few hundred bucks if you have some mechanical skill.

If your're having idle problems, I suggest that you find my thread about thoroughly cleaning the intake manifold and read through it. I assume that it needs to be cleaned out if you have the ability to follow what I did, or at least take off the throttle body and clean behind it, then replace all the cheap rubber breather tubes on top of the engine.

 

Hi, I don't have idle issue. I am a little handy and did do the work myself and saved a ton of money. I might give the cleaning of the throttle body a try. How hard is it to take the throttle body off? Do you know where I can purchase the rubber gromments your talking about from? Do you what they are actually called? I also read your thread and I think you conclusion was a bad fuel filter? I might try that as well. I just don't understand why after disconnecting the battery it has good power for about 10 minutes then goes back to loss of power?

 

The conclusion of my idle issue was that the thorough dis-assembly and cleaning of the intake manifold solved the issue. The fuel filter did nothing. The TB is easy to remove, 4 bolts on the back side of the intake manifold. There is a large rubber O-ring behind it that is necessary to replace after removal. There are also rubber rings that seal the air intake box to the elbow and elbow to the TB, they are cheap and could be replaced as well to seal the air path.

Also, I hope you installed the genuine Bosch MAF, as many cheap knock-offs are reported to have problems.

 

Unfortunately, I bought a cheap knockoff MAF. Money is tight and I didn't want to just start throwing alot of money at the car just guessing at what the problem is. I did reinstall the Bosch MAF and it went back to normal( still loss of power but normal) . Is the throttle body in the front of the engine or rear? What did u use to clean it? Your clk looks sweet! What size rims and tires are those?

 

Do you know why after disconnecting the battery, the car has good power for about 10minutes and then goes back to loss of power?

 

Disconnect the MAF and see how it runs. That will force the computer to use "fail-safe" settings rather then possible bad readings from the MAF sensor. There is a special cleaner spray at auto parts stores for MAF, but that probably won't do anything if its really bad.

I spent the money to replace mine, but that did nothing for my idle issues either.

The TB is just below the MAF, air flows through the MAF and into the TB.

I have no idea why it would loose power like that. I would only guess that there are bad sensor readings somewhere. I'm surprised that the dealer could not find anything with their fancy computer. Maybe your feelings are normal, as the computer re-learns after a battery reset, I can't tell how much "power loss" you're having. I assume you don't get any kind of warning lights on the dash.

Dealer techs don't really know about troubleshooting anything these days, they just plug in the computer and if it does not tell them anything specific then they are lost and just tell you to do the tune-up stuff that they told you. Maybe you should find an "old-school" mechanic that specializes in Mercedes. They might have the experience to know your issue if it's as noticeable as you say.

Rims are 19" staggered, 8.5" wide front, 9.5" wide rear, check out Roderick brand, or there are some that seem to be a copy on Ebay listed as "Euromag" brand.

 

I don't have any reported codes or malfunctions showing but I did notice that the ABS malfunction came on after unhooking the battery and it went away after about 10 minutes as well. I also noticed something strange the other day. I installed a amplifier and sub in the trunk about 2 weeks ago and a couple days ago after it rained I went to take it for a spin and the amp was in protect mode and was wet on the outside of it ,almost like it had dew on it but it was in the trunk out of the weather. Soo I thought, why does my amp have dew on it? I just bought the car used off ebay and was thinking, does it have a sunroof leak and that's what caused it? I'm not sure if it was a one time thing BC I just installed it but will keep you posted. Ill try the MAF disconnect procedure later today and let you know what happens. Soo, it should run different once I disconnect the MAF and that will tell me if mine is bad? Also, about the rims and tires, the clk430 comes with 7.5 on the front and u are running 8.5. Do they stick out a little farther than the normal rim and tire?

 

My 19x8.5 on the front do not rub the fender because they have the correct offset, which I believe is 32. These are made specifically for Mercedes with correct offset, and they fit the OEM center caps, which makes them look nice and original. There was another recent thread about other 8.5 wide on the front that were rubbing, probably offset is wrong. They do stick out just a tiny bit past the fender if you look straight down, but nearly flush, which looks good.

As far as moisture in the trunk, that is definitely bad, so you need to find the source.

If you start the car with MAF disconnected and it runs better, then your sensor is bad, but I don't know how it would run under normal driving like that for 10 minutes or more.

I'm thinking there may be an issue with your cats, because it may take about 10 minutes for them to warm up to operating temperature, then the computer starts taking input from the O2 sensors and adjusts the fuel/air mix. If this were the case, I would expect you to get bad idle, and possible OBD2 code / light on the dash. If the cats are "clogged" it may idle fine, but have no acceleration power as the engine tries to blow the exhaust gasses out upon acceleration. If you hear rattling under the car, that's bad, maybe the cats have broken up inside.

Again, it's hard to get an understanding of what you mean by "reduced power" after 10 minutes. Is this every time you start and run the car, or just after you perform a reset by disconnecting the battery? If only after the battery reset, then it's probably just normal learning of the engine and transmission as the computer settles in.

 

No rattling under car. The car has loss of power all the time but when I unhook the battery it has good power and responseds well to gas pedal. What I mean by loss of power is exactly what shannony posted on this thread. The same exact thing. Would I be able to drive down the road with the MAF disconnected? BC thats the only time I can tell. Also do you know exactly how far your front tires and rims stick out past the stock factory rims and tires? 1/2 inch? The reason I'm asking is BC I'm seriously thinking about getting a set.

 

It looks like the OP had no resolution. I suspect that it's just normal engine and trans adaptations in the computer that you feel are less powerful or responsive.

You may want to look at getting the Sprintbooster module for increased throttle response. I want to try one, but I can't bring myself to spend $300 on it. The car already has more power than I can realistically use on a daily driving basis in the city.


These rims came with my car this way, but after feeling the ride for a few years, I would probably trade them for 18" with a little more tire to soften the ride. I really like these and they are very affordable:

http://www.oewheelsllc.com/Wheels_3/...3#.VMkoMCvF9Zo

Scroll down that page to see the example pic on a W208. I think that pic is on the form somewhere as well.

The 19" look great, but I think I would sacrifice the look to get a little softer ride. A new set of tires on mine did recently improve the ride a little.

 

What does the OP having no resolution mean? Do u think riding down the road a mile or two and punching the gas will be ok while the MAF is unhooked?

 

I don't know man, I'm not a mechanic by trade, so I won't say yes or no. I have run mine at idle several times with MAF unhooked and had no problem. I can't remember if I drove it like that.

OP = original post

 

Hey Guys,

Been off line for a while and have just read through all the posts, first things first throw the cheap MAF in the bin i got a cheapy and it literally lasted about 1 week before being worse than the original bad MAF. I didnt replace it with a Bosch only because it was easier to source a piersberg (german) MAF in aus which has been great.

I haven't had the issue in a long time now since i posted this and literally the only thing i have changed is i had a large split i found in the air intake from the bumber into one side of the air filter housing. I read that it can throw the MAF into some sort of frenzy. It has been touch wood great ever since. Ocassionally if i am just doing a lot of around town driving i do the soft reset on the tranny adaptions also which just beats having to have the ECU learn that you want to give it a hammering out on the freeway

Hope you get it going !

 

I did what we talked about with the MAF. I unplugged it and ran engine and their was no difference between unplugging it and plugging it up. I did reinstall the cheap MAF I bought and it made my car idle up and down and turn the engine off a couple of times. How can these people manufacture a piece of junk and call it a OEM replacement. Do they even test these cheap MAF Before they sell them. I spent $40 and it is complete junk. Why didn't they send me a donut instead of that piece of junk. At least then I would of had something to show for my $40. I timed my 0-60 time and it was around 7-7.5 sec. I get around 18-20 MPG. I think I'm going to change the fuel filt er next and see if that does it. I'm thinking it has something to do with fuel. Anyways, are those rims u have a +32 offset or a -32 offset?