CLK 320 W208. Help greatly needed please.

[steadyeddie]

Hi, I have a 1999 CLK 320 and for the past few months I've been chasing a problem with the car but so far to no avail. Starting to lose my marbles now so I'm really hoping someone can help.

On startup the car is fine, however occasionally when exceeding around 4000rpm the car suddenly loses power dramatically (quite dangerous when it happens on the motorway). The additional issue is a very rough idle, but only once the problem has been triggered by exceeding 4000rpm.

If I restart the car the problem goes away, however I can replicate the issue.

I took the car to a specialist Mercedes garage to have any fault codes read on a Star machine. The two that popped up were P0150 O2 Sensor Upstream and P0306 Misfire Cylinder 6.

The garage told me that the car needed more diagnostic work, however I decided to pay for the test and try to fix the problem on my own.

After LOTS of reading on this and other forums I decided to tackle the problem with a parts gun. The car has 63,000 miles on the clock so many of the parts replaced would keep it on the road longer and hopefully fix the problem.

I then:

Replaced all 12 spark plugs with Bosch platinum
Replaced all 12 Bosch ignition leads
Replaced Bosch fuel filter
Replaced Bosch coil pack on cylinder 6
Replaced Bosch MAF

Unfortunately none of these fixed the problem so I took the car back to the same garage for more diagnostic work. They had the car for two days, then I received a call to tell me that they thought they knew what the problem was and would need to carry out two more tests.

1). An engine pressure test
2). Take the exhaust off to check for a blocked catalytic converter.

I was informed that if the engine pressure test failed the car would be a write-off and the cost of replacing the cat(s) would be between £800 and £1200.

So...I paid for the diagnostic work and took the car away.

After more reading it seemed apparent that a blocked cat wasn't unusual, and that the car could still pass the MOT with both downstream cats removed.

Last weekend I can both cats removed, however I still have the problem :-((

This week I'm going to replace both O2 sensors, but if that fails I think I'll be close to giving up!

Any help at all would be greatly appreciated as I really want to keep this old girl running for many more years.

 

[Ted]

One word. MAF.

This is a common problem on these and sounds pretty much the same as on mine - mine also lost power just as you went to pull away on occasion - not good on a right turn.

Definitely worth a try.

 

[steadyeddie]

Sorry completely forgot to say that I did replace the MAF too.

 

[Ted]

Ah... only other thing is possibly the brake light switch - ECU thinks you are braking. These have multiple contacts, so the brake lights working doesn't guarantee it is working correctly. Cheap and easy to replace, I believe.

Also, with the MAF, it is recommended to use a genuine/Bosch as the quality of the pattern ones is variable.

 

[steadyeddie]

Thank you Ted I will check how much it is to buy a new one of these

 

[shadenfroh]

I also had the exact same issue caused by the MAF. Did you replace the MAF on your own or did you have a shop do it? Did you replace the air filter when you replaced the MAF? On the really really really off chance that you got a defective MAF or you buggered it up during installation, any shop with STAR can verify that the sensor puts out valid data.

By the way, I believe you've already learned that attacking a MB with the parts gun rarely ends well. If you had asked beforehand, I think many people (me included) would have told you to leave the parts you replaced alone. Go to another shop that owns STAR Diagnostics and have them inspect the car. Go to the dealer (even though indies generally have more experience with cars at such age). These cars sing like birds in the right hands.

Keep us posted!

 

[steadyeddie]

I've actually had the MAF replaced twice.

The first time the garage replaced it then took the car for a drive and the fault was still there. They kindly then removed the new MAF and I was able to get return it.

After lots more reading online the solution for most people was a new MAF. I therefore decided to buy a new MAF and fit it myself. Unfortunately the result was exactly the same.

Knowing that these are known to fail over time I decided this time to just keep the new one fitted.

 

[Benzmanc]

I had the exact symptoms you describe albeit on a Peugeot 205 GTI. The car would run great until hitting around 4000rpm then it would be lumpy as hell and constantly try to cut out. The only way to stop this was to switch off and back on again.

The culprit was the throttle position sensor, I found out the fault by unplugging it and the car revved up fine.

May be a long shot but it sounds like you've tried everything else.

THROTTLE POSITION SENSOR Mercedes Benz CLK Class Coupe CLK320 C208 3.2L - 218 BH | eBay

 

[markmifsud]

Check for water in the fuel rail. I believe it nearly always hits C6 for a misfire.

 

[crisc204]

I've a Snap-On diagnostic with the leads etc it can read the car but STAR is quicker easier and goes in-depth.
Launch diagnostic is also pretty good on old Mercedes
but... they are only as good as the mechanic holding the machine...

I've just had to buy the old MB specific leads and ID keys so that it can talk to my car a 97' w208 320 V6

...Those two fault codes are likely nowt to do with power loss, they could even be from the first garage disconnecting stuff to diagnose.
if you have not checked actual values before swapping parts

Also check the wiring to the MAF is intact and the multi plug is undamaged

It's probably a Speed sensor or poss Gearbox fault knocking the car back in to Limp as it fails or sends out of spec information.
Maybe the drive by wire throttle messing about with actual values not matching requested values and all that malarky.

When any of this happens the ECU recognizes as a fault and turns of the power to protect the car


... but it's worth getting on a STAR or oscilloscope and checking actual values of the important sensors
(some cars can run with several sensors down but will rely on other systems this some can't TBH I'm not sure without checking the car out)
Any mechanic should be able to spot the fault, I've only had to check my car out this once in 10+ years the rest was just regular servicing and basic maintainance.
(I'm a specialist in the other lot from Stuttgart)

My CLK has done this twice as per your symptons recently, on mine its 100% the gearbox dicking about with an intermittent fault.

hth

 

[steadyeddie]

Fixed!

I'm not quite sure how, but my car is now running better than ever before.

It was almost as if there was a clog somewhere in the exhaust and through some spirited driving it got better and better.

It wasn't the rear cats as I had those removed, so perhaps its was one of the two upstream cats that needed cleaning?

I went to get my steering alignment done and while I was there discussing my issues one of the chaps who worked there kindly poured a bottle of cataclean into the fuel tank.

It must've taken a hundred miles or so to work it's magic.

 

[mbenz1]

I'm not quite sure how, but my car is now running better than ever before.

It was almost as if there was a clog somewhere in the exhaust and through some spirited driving it got better and better.

It wasn't the rear cats as I had those removed, so perhaps its was one of the two upstream cats that needed cleaning?

I went to get my steering alignment done and while I was there discussing my issues one of the chaps who worked there kindly poured a bottle of cataclean into the fuel tank.

It must've taken a hundred miles or so to work it's magic.

Glad to hear it's well again. Sometimes these fuel tank additives can do some magic.

Out if interes, did you replace the MAF with a genuine MB / Bosch one or a aftermarket one? Also, as mentioned in one of the previous posts, it's a good idea to change the air filter if it's bad. If it's clean then should be fine.

Sent from my GT-I9505 using MBClub UK

 

[steadyeddie]

Problem has returned :-(

Is it possible for the primary cats to get blocked? After using Cataclean the car drove fine for a couple of weeks. Will I do any damage by using another bottle so soon?

 

[markmifsud]

Hi Eddie, can you read back over the replies as others have asked questions to try and assist but you have skipped past them.

 

[shanksy]

Hi Eddie, have a look at my thread regarding my 124 coupe. I have a fairly similar issue with loss of power and then misfiring which then resets when you restart the engine.
Mine turned out to be the timing chain has almost snapped and is flapping about.
Almost certain anyway, the garage diagnosed it as such, I will know in the coming weeks once the replacement has been attempted.

Funnily enough, I have purchased a CLK as a runaround in the meantime, got a rusty old 430 for under a grand that is mechanically sound. Locving the sound of the V8

https://www.mbclub.co.uk/forums/engine/222129-w124-e220-coupe-loss-power.html

 

[RyanMuller]

When I had this problem it was a crank angle sensor. turned car off and on again and it was OK for another 15 mins

 

[W20855amg]

Hi
use original parts only
Only way to sort problems out