clk 320 sometimes not firing up

[Jamie_sg]

Hi newbie here just bought a 1998 clk 320 coupe, first day i had it was fine, until i parked up at a friends and when i came out to start the car it just turned over but wouldnt fire, tried it several times but nothing. I had 2 keys with the car and the master reset key so i tried all of them but still no joy, came back to it an hour later and it went straight away. Following day i was using it all morning starting and stopping with no probs but then same thing when i parked up for a while and came out it took about 5 or 6 seconds to fire up, slightly worrying as i dont want to get stranded anywhere, seems like the immobiliser isnt turning off, its not even attempting to fire up...any suggestions?

 

[shayes]

Don't know if its any help but with my W140 series if you delay the starting sequence for more than a few seconds you have to lock the car and unlock. Suprising how quickly the time passes and then have to go through all this palava.
It only takes putting something in the boot or back seat or just extending the wing mirrors.

Handbook should clarify.

 

[television]

Hi newbie here just bought a 1998 clk 320 coupe, first day i had it was fine, until i parked up at a friends and when i came out to start the car it just turned over but wouldnt fire, tried it several times but nothing. I had 2 keys with the car and the master reset key so i tried all of them but still no joy, came back to it an hour later and it went straight away. Following day i was using it all morning starting and stopping with no probs but then same thing when i parked up for a while and came out it took about 5 or 6 seconds to fire up, slightly worrying as i dont want to get stranded anywhere, seems like the immobiliser isnt turning off, its not even attempting to fire up...any suggestions?

Hello and welcome,it normally the CPS sensor that causes this and very common,,£47 from a Bosch Service center

 

[Uncle Benz]

Hello and welcome,it normally the CPS sensor that causes this and very common,,£47 from a Bosch Service center

I reckon he's right, you know.

 

[Renoir]

Hi,

I found a lot of topics about CPS and what it does when faulty. A year ago I started having occasional problems with starting the engine (3.2 M112). I am connecting it to a computer once in a while but no errors ever appeared after those starting problems.
This summer I decided to fight this problem because it started annoying me more often. I purchased the CPS (original MB part) and had it replaced. After one week the problem was back. I went to the dealership this time and they checked all they wanted and said it couldnt be anything else but the CPS. They cleaned the plug and socked since the part was changed. After another week I got the same starting problem, and returned to them. This time I agreed that they install CPS from their own stock and at their price. After another week the problem was back again. Tomorrow Im going to visit them again.
But I have serious doubt whether they will be able to solve this.
It works like this: after driving I return to the car in about 10 minutes and it kinda starts revving but then misfires and stops in a matter of seconds - and it works like this for about 1 hour until it has cooled off a bit.
When it has cooled off, it starts cranking without any fire. For about 30 minutes.
Then it cools off yet more and at some points starts like pleasure.
To make it much worse one time it also didnt start with a cold engine. The car was sitting in the sun for the most part of the day and in the late afternoon I wanted to drive it but couldnt start it. It was cranking in vain. In about 1 hour it started...
Everyone I have talked to thinks its complete mistery. I have no idea how to repeat this problem when the car is in the garage. This problem is so intermitent. It could start perfectly well for 20-40 times and then fail for nearly 2 hours. Now it looks like it isnt much connected with the engine temperature. It failed starting on a cold engine too.

Anyone has any ideas?

 

[television]

This could be anything from an ECU or fuel related were there no fault codes

 

[Renoir]

anyway, its weird like hell. All computer readings are clean. I have no fault codes on ME. The car is quite clean in this respect. I have only some CAN faults (warnings indeed) that appear to be related to cuts in wires made when installing an additional immo.
Fuel system was the first thing to check at the dealership. I hope they know what they are doing. They said it was ok. But they received the car with no problem.

 

[television]

Sadly we do get these awful faults, one day they may all go away

 

[Alex Crow]

non starts rarely log fault codes. ideally you need to test when the starting fault is present. i would connect a fuel pressure gague to the fuel rail and test acv from the crank sensor with a dmm - chances are it`s either fuel pressure (eg blocked/defective filter/regulator or pump failure) or poor crank sensor signal.

 

[Renoir]

Looks like we have a believable cause.
I have an immobilizer installed which cuts off the fuel pump through a relay. This relay may be faulty and not restore power to the pump under some conditions such as heat which is usually generated by driving but may sometimes accumulate from the sun too.

By the way, I got really lucky because after leaving the car at the dealership it had this damn problem. Too bad they spent an hour and didnt get a clear picture why it doesnt start. In an hour it was working again. During that test time they found that the fuel pump didnt receive any power - both + and - wires were dead.
So everyone thinks its the immo.

 

[television]

This should only be dry joints,,a hard whack on the box when it will not start may prove the point

 

[fastboysparky]

Hi. I am having the same problem with my ML 270cdi. Just changed the crankshaft position sensor (which did have a low reading) but the problem is still there. If you leave the car for more than a few minutes when warm, it will not start again until cold, sometimes it fires and stops, otherwise it justs turns over.
Gonna strip it down this afternoon, i'll keep you posted if i find anything.
P.S. my ML is totally standard with no after market immobiliser.

 

[Alex Crow]

renoir, have the immobilizer removed and ceremonially cremate the damn thing. aftermarket devices such as this cause far more problems than original electronics. your car should have a transponder key anyway so the immobilizer is pointless - a real pet hate of mine.

 

[fastboysparky]

You really need to check the camshaft position sensor, they store readings from initial start up and then could be unplugged once engine is running, this is why once the engine is running it is ok. Then the sensor breaks down as it heats up, you stop the engine and it wont restart cause it needs to read position. As a test, get engine upto temperature or until it wont start then take it off and put it in freezer for 5mins to cool it down. refit it to car and it should start. If you leave securing bolt out just for testing you can do this procedure very quickly.
I went one step further and whilst the car was cold i heated up the sensor, the car would not start, i put it back in the freezer for 5mins put it back on the car and it started. Sounds crazy but worth a try, let me know.

 

[Alex Crow]

engine management should log a synchronisation code if it sees the crank signal but not the camshaft signal. lets hope it was this pointless and troublesome immobilizer, did i mention i don`t like them