Misfires on CLS55 AMG

[7om]

Hi Guys,

Having difficulty with my CLS. It was plugged into STAR today to try and find the fault but it's been inconclusive.

The problem. Car runs fine 80% of the time but occasionally develops a misfire. This problem existed before I modified my exhaust but I have since removed all CAT's and fitted manifiolds.

The problem seems to occur mostly with town driving or after idling in traffic etc.

I have a EC remap with smaller pulley but those are the only mods.

Whilst the car was connected to STAR it showed intermittent misfires on each cylinder over a period of about a minute. It wasn't just one consistently.

Has anyone had this issue before?

Once I switch off the ignition for a minute and restart, it runs fine again and I can make loads of noise again, sometimes for a whole day without any problems then suddenly, at a junction or pottering around it will nearly stall and go lumpy. I'd rather it was permanent so I could locate it.

Any ideas or feedback much appreciated. I'm driving down to the South of France on Friday so really hoping a coil pack is the issue.

All plugs changed last week to NGK IR.

If I can't fix it I'll pop it up to MSL when I get back and I know they will be able to sort it but worth asking on here first. Paul at Eurocharged said to try switching a coil pack so I'm ordering some now but any other ideas welcomed so I can turn over as many stones as possible before I go away.

The guy who did the diagnostics said to put the car back to standard...Only in Cornwall!

Cheers,

Tom

 

[Cyclone1]

Coil pack / plug / O2 sensor. If all cats are removed and exhaust / manifold modified then could be too free flowing especially if this was done post the remap?

 

[7om]

Thanks for the reply, the problem was there prior to the exhaust modifications.

The problems listed on the screen were,

Idle Speed control Implausible
B28 (Pressure Sensor) Signal Implausible
B28 (Pressure Sensor) Signal Implausible
Misfiring (P0300)
Misfiring Cyl 1
Misfiring Cyl 7
Misfiring Cyl 8

But the guy still thinks the problem is no rear 02 sensors (even though they are still in)

All cylinders were misfiring during the smooth running test. He did the test whilst it was running lumpy rather than smooth after turning the ignition off.

 

[Suky Sangha]

Hello Tom I'm not giving your cats back

Sent from my iPhone using MBClub UK

 

[Suky Sangha]

Take it to acid or Andy ,Paul / ec they will sort it out.

Sent from my iPhone using MBClub UK

 

[ChrisA]

Check coil packs are set in the right order 1st. Then re-check plugs and gaps...
If ok then order new O2 sensors and a retune may be in order

 

[ChrisA]

These Pdf files may help you or point your nearest Indie in the right direction..

View attachment CEL is on with code P0300-P0312 stored_AF07.00-P-8641A.pdf

View attachment 52168

Also check for bad gaskets on the supercharger manifold and surge tanks.....always causing issues like yours

 

[7om]

Hi guys,

Thanks for the feedback. I might try new 02 sensors but surely the star diagnostics would have said one was faulty. I think as I've removed all the cats, it could likely use a retune anyway. I've changed two coil packs which had indicated misfires, no change. MSL or Paul at Eurocharged will be able to fix it.

The codes etc would help but the local guys down here don't like touching modified stuff. "Put it back to standard, MB knows best" is all you will get, ha.

 

[7om]

Found the Issue CLS 55

Hi Guys,

Just posting this for anyone in future using the search function with a similar misfire and cylinder shutdown issue as it would have helped me.

I've found a decent local Merc tech with star kit and he took the time to methodically test each system rather than just give me a printout like another local firm who just wanted the diagnostics quick cash (Put it back to standard was the advice!)

So, O2 sensors voltages are ok, coil packs are ok. But after running the reset calibration mode he noticed that the throttle body starts off at 1.5 (the specified range is (1.1-2.5) but drops to 0.3-0.6 to keep the mixture in check because air is getting in somewhere, so the ECU is adding more fuel.

So it's been narrowed down to an air leak...somewhere under the supercharger. He said that when adding a pulley and/or remap, it can sometimes push the old gaskets over the edge with the extra heat and boost if they were already on the way out.

Its an easy job to swap all the gaskets with two people, roll on Sat morning.

Worth checking for a similar issue if you encounter the same problem as misfires and a the car dropping a cylinder usually leads people to the plugs and coil packs.

Thanks to Acid at MSL and Paul at Eurocharged for pointing me towards intake leaks but sadly the other garage dismissed their guidance and said I should start by putting it back to standard.

I took him for a spin after the reset as the car drives fine under load although I'm probably losing some power due to the air leak.

On the plus side he said the map (Eurocharged) is smooth and progressive compared with some of the poorly remapped 55 engines he's seen over the last 10 years so thumbs up to Eurocharged and MSL.

Hope this helps people in future if you get the same issue.

 

[E55MO]

Hi Guys,

Just posting this for anyone in future using the search function with a similar misfire and cylinder shutdown issue as it would have helped me.

I've found a decent local Merc tech with star kit and he took the time to methodically test each system rather than just give me a printout like another local firm who just wanted the diagnostics quick cash (Put it back to standard was the advice!)

So, O2 sensors voltages are ok, coil packs are ok. But after running the reset calibration mode he noticed that the throttle body starts off at 1.5 (the specified range is (1.1-2.5) but drops to 0.3-0.6 to keep the mixture in check because air is getting in somewhere, so the ECU is adding more fuel.

So it's been narrowed down to an air leak...somewhere under the supercharger. He said that when adding a pulley and/or remap, it can sometimes push the old gaskets over the edge with the extra heat and boost if they were already on the way out.

Its an easy job to swap all the gaskets with two people, roll on Sat morning.

Worth checking for a similar issue if you encounter the same problem as misfires and a the car dropping a cylinder usually leads people to the plugs and coil packs.

Thanks to Acid at MSL and Paul at Eurocharged for pointing me towards intake leaks but sadly the other garage dismissed their guidance and said I should start by putting it back to standard.

I took him for a spin after the reset as the car drives fine under load although I'm probably losing some power due to the air leak.

On the plus side he said the map (Eurocharged) is smooth and progressive compared with some of the poorly remapped 55 engines he's seen over the last 10 years so thumbs up to Eurocharged and MSL.

Hope this helps people in future if you get the same issue.

Thank you for posting this.

even though i am not getting a misfire. I do have a similar (sort off) issue.

With the 84mm pulley installed on the e55k there was a lot of heat.

currently the AFR are way off, logging at 10.1 at WOT. Have tried everything to sort this out. New coilpacks installed, spark plug depth checked and on Friday acid confirmed they had swapped out the boost pressure sensor. But i never got an update to confirm if this resolved the issue i think sarim was going to pop thebeast on the dyno.

With acid off on holiday i will ask sarim to check for vaccume leaks as that may just sort my issue out.

Then i can finally have the 77mm pulley and map installed.....

Thank you for posting this

 

[7om]

Hey no worries,

The 77mm pulley and remap is also next on my list with MSL. I just want to sort my cooling first of better IAT's. Split cooling, EC heat exchanger and a custom boot tank I've started making. I've read and heard Sarim is great at troubleshooting so if the car still has any issues I'll be asking him to kindly look over everything for me.

Good luck!