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Discussion Starter #1
Hi again I ve got a slight miss fire only at idle I have tried the following so far:
Ive changed the plugs
Ive changed the Air flow meter
Ive changed ALL the mounts
Ive smoked all the vacuum hoses for air leaks
Ive also put the coils etc on a scope and the only thing I can find is a slight variation on the negative side of the low voltage coil. Basically I believe it should be smooth and im getting a spike every so often.....
Any more ideas please
 

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Premium Member 2014 SLK55 AMG
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1,665 Posts
I've had a very, very slight surge and some unevenness at low power and low load on my 2002 320 slk. Played around with a few things, replaced air filters and I'm waiting on a fuel pump but in the past couple of weeks I've had 4 or 5 instances of bad misfiring on 1 and 2 and the last time on 3 as well, requiring the engine check light to be reset with my torque setup.

Today the latest misfiring was accompanied by an error log of a suspect 02 sensor on the same side of the engine so I have ordered a replacement ( £35 on eBay as opposed to £235 from Merc! )

I'll replace it when it arrives and let you know if it fixes my problem.

With the removed item I can plug it in to the other bank and see if the fault follows the sensor.
 

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Premium Member 2001 SLK320 Wizard of ID
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589 Posts
I've had a very, very slight surge and some unevenness at low power and low load on my 2002 320 slk. Played around with a few things, replaced air filters and I'm waiting on a fuel pump but in the past couple of weeks I've had 4 or 5 instances of bad misfiring on 1 and 2 and the last time on 3 as well, requiring the engine check light to be reset with my torque setup.

Today the latest misfiring was accompanied by an error log of a suspect 02 sensor on the same side of the engine so I have ordered a replacement ( £35 on eBay as opposed to £235 from Merc! )

I'll replace it when it arrives and let you know if it fixes my problem.

With the removed item I can plug it in to the other bank and see if the fault follows the sensor.
Good luck!
 

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Premium Member 2014 SLK55 AMG
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1,665 Posts
Replaced lambda sensor this afternoon, off sailing for two weeks in Greece so really won't get to test it until month end but it does seem smoother in the short test drive I did.

Here's hoping!
 

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Premium Member 2014 SLK55 AMG
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Hmm problem still not fixed. Suspect fuel pump is on the way out.
 

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Discussion Starter #8
Done a engine compression test all fine. Spoke to mercsed they said def fit a geniune Mercedes Air flow meter I said I had fitted a Bosch one and they were trying to tell me thats not geniune. Hmmmm I give up on Mercedes as they said fitting a geniune one will solve it. I tried to tell them the one they sell is Bosch they said no it isnt. I let them ordewr the part in and I said if its Bosch I dont want it. Got a phone call to say its not bosch its a geniune mercedes and this will def solve the problem. I opened up the mercedes box.............Guess what Its got Bosch stamped on it. A few arguments later them trying to tell me its a geniune mercedes Bosch one which is different. I phoned up Bosch in harefield and they told me they supply to Mercedes and Mercedes re package them into there own brand. I rest my case....So they wanted to sell me a part for £279 which I can purchase in Bosch for £96+vat.
 

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Done a engine compression test all fine. Spoke to mercsed they said def fit a geniune Mercedes Air flow meter I said I had fitted a Bosch one and they were trying to tell me thats not geniune. Hmmmm I give up on Mercedes as they said fitting a geniune one will solve it. I tried to tell them the one they sell is Bosch they said no it isnt. I let them ordewr the part in and I said if its Bosch I dont want it. Got a phone call to say its not bosch its a geniune mercedes and this will def solve the problem. I opened up the mercedes box.............Guess what Its got Bosch stamped on it. A few arguments later them trying to tell me its a geniune mercedes Bosch one which is different. I phoned up Bosch in harefield and they told me they supply to Mercedes and Mercedes re package them into there own brand. I rest my case....So they wanted to sell me a part for £279 which I can purchase in Bosch for £96+vat.
I had the Bosch air flow meter and it didn't improve things. I switched to the Mercedes branded one (stamped with Bosch) and ran smoothly from that point forward. From what was explained to me, Bosch manufactures one based specifically on Mercedes specifications and can not duplicate the exact part outside of that. Bosch does make others that appear to be the same but does not meet the technical specs and doesn't perform the same.
 
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