Here’s the story:

So my 2005 E55 160k miles has been basically sitting on and off for the better part of a 2-3 years. I was moving around the country, and didn’t take my E55 with me. Every couple months when I would make my way back home, I would tinker with the car while in storage. Start it up, sometimes the battery would need to be jumped, but the car always fired up. And ran smooth, as it always has.

so within this last year, I finally was able to trailer the car down to where I was living. Then decided to start dumping money into the vehicle. I’ve owned it since March of 2013 and at this point I can’t part ways with it. Sometime back in 2015, I recall the car misfiring under acceleration. I discovered that the purge valve vacuum hose would sometimes blow off. Fixed that issue.

fast forward to 2019, fire up the car up on a cold start - it runs smooth can rev it high. Put it in drive and i can even get a good pull or two, and then the car starts to sputter and then CEL pops on and begins to flash repeatedly. (Much like it was doing in 2015, but this time no hoses seem to blowing off under load) So I take it back home, run the codes, I was getting cylinder 2 & 4 misfire. Logically first thing we checked was the ignition system, tested ohms on all spark plug wires (on both sides even), plugs (stock ngk) have around 100 miles on them but definitely a lot of plenty of idle hours on them they’re a little dirty but I think they’re good, Swapped coil packs to the other side and the mis didn’t move so those are good. Even tested the compression, all within spec 150-160psi. There’s only so much I can test with ignition and it all checks out.

For our next diagnostic, and this is where it gets interesting, we fired up the car and on bank 4 and 2 where the Supercharger sits on the block, directly next to the valve covers, sprayed it with brake clean and it smoothed out! Naturally, we got excited about this, thinking we might have discovered something. So we cleared the CEL and I started the car while my friend spray that exact spot with brake clean again. The car ran smooth the entire time while he was spraying, as soon as i stopped the engine began to sputter and within a few seconds the dread flashing CEL came back on.

By this time we are convinced he have a vacuum leak. We’d like to smoke test it to confirm our “educated” theory, but our autozone and oreilys didn’t have one. But I was convinced we had an vacuum leak, why else would the engine smooth out and run without any misfires while we sprayed the break clean on the cylinder that is giving us a code? It made sense that there was probably a gasket leak where the supercharger sits on the block.

So we ordered gaskets for the blower on FCP. Both gaskets where the supercharger meets block, the gaskets where the surge tanks sit on the blower, the rear gaskets for blower, and there was cylindrical gaskets for where the intercooler connects to the blower itself.

oh, yeah, just for good measure due to the age and mileage. We sent off all 8 injectors to be cleaned. Turns out two of them where dumping fuel, being stuck open. The company we sent the injectors to were able to clean all the injectors back to factory spec and replaced all the o-rings.


Fast forward to yesterday, after nearly a week of waiting for parts and injectors. We had everything to reinstall install the blower. Very hopeful all this time energy and money wasn’t a complete waste.

we put everything back on the vehicle as it should be, obviously cleaned all the mating surfaces between the blower and the block. Triple checked that everything was in place where it needed to be, and it was. We were ready for the first start up. It was running great, let it run for maybe 5-7 minutes to heat up. Revved it a few times. All things that, before doing this job, would have triggered a misfire but not this time. Spirits were high, we just needed to take it for a test drive.

I drove it for maybe about a mile, gave it about 30% throttle and it was running great! The boost worked too. But then the car began to sputter and then the CEL popped back on and began to flash. Damn it . Now we’re back at the starting point, that work we did probably needed to be done but it didn’t solve our issue.

we ran the codes again, and now the ENTIRE passenger side bank is giving misfire codes. Cylinders 1,2,3,4

So we tested for a blown head gasket via coolant, and it passed that test. again, we’re confident it’s not my ignition components. So maybe vacuum leak? I’m not sure, we’re kind of at a loss and feeling defeated.


variables to consider:

83mm clutched pulley

mid-length headers. cats deleted, o2 sensors are still inplace

eurocharged tune (car also did this before the tune, so I’m confident it’s not the tune causing the issue. But the tune does prevent o2 sensors from triggering a code. Although I do remember before getting the tune, I had a code for a bad o2 sensor. I can’t recall which one, this couldn’t be causing the issue can it? Being that there’s no cats and it’s disabled in the ECU)

any input would be appreciated.


here are a few photos of our job and the codes and o2 sensor reading (somebody with more knowledge than us said those o2 sensors readings are too perfect, so idk what to make of that)




Ignore the broken radiator fan shroud









Believe it or not, RTV gasket maker is the correct way to do this. I didn’t believe it at first.

Everything back on, just waiting for injectors


Codes after all the work and test drive

Lower two reading are the o2 readings, for whatever that’s worth

 

Could possibly be an electrical problem, maybe ecu. But make sure the vacuum hose that's held down by the valve cover bolt on the driver side is plugged into the supercharger. I had a problem with mine after changing the valve cover gaskets, my car would drive fine until I let off the gas then it would drive like it was missing until I turned the car off and back on. I never got a misfire code though.

 

Getting a smoke test done is always a good way to go before going deeper...

In this post I placed a few links to videos on how to make an easy DIY smoke tester which saved my life.

https://mbworld.org/forums/w211-amg/...ml#post7889963

 

Check fuel pressure

 

Have you checked the me to see if their is oil or corrosion?

 

thanks for the reply. We are currently making a home made smoke test. We are having a issue with it creating a lot of smoke, I hope it’s because of the polyester socks we used, being mostly plastic the soldering iron just melts a hole in the sock. Couldn’t find 100% cotton socks at Walmart believe it or not. So I found a wick like piece of 100% cotton Fabric in the craft department. Gonna give that a shot, hoping that solves my issue. I’ll keep you updated.


I forgot to mention in the OP. we checked fuel pressure, it’s at 80psi which is within spec. And like I said , we injectors were sent off to be pressure cleaned and operation all within spec. Thanks for your input.

 

where should I be checking for corrosion

 

UPDATE:

smoke tested the car, found two leaks


MAJOR vacuum leak on that multi-piece brake booster plug. I found a post related to that piece and seems to be fairly common that o-rings get hard and then the plug begins to leak. Raead a few people recommended to use RTV to seal it. So we did that at best as possible.

we ran the DIY smoke tester again and no vacuum leaks at all. So we’re confident that fixed the vacuum leak.

I also read that somebody had that same issue and he also had a very heavy leak out of the brake booster plug and he fuel fouled his plugs. So I’m sure I’ll need to replace my plugs. And hopefully this will solve the misfire issue.

stay tuned

 

Good find, holding thumbs for you.

 

UPDATE:

Cleaned the plugs with a Pneumatic spark plug cleaner, they plugs have only 100 miles and the electrodes were fine and resistance was within spec - they were just dirty. Torqued them down to spec, made sure the wires were on the spark plugs and coil packs correctly. When I took out bank 4 spark plugs, I could smell fuel. We ran the smoke test again, and absolutely NO vacuum leaks anymore. took it for a test drive, nothing has changed. Still get the occasional flashing CEL. What’s weird is sometimes the engine is smooth for 10-20seconds , and then it starts to misfire again. Like I said, we checked compression and that was all within spec.

So, no air leaks, ignition components are fine, fuel pressure is within spec.

Reset the CEL, checked for codes again and still getting cylinder 2 & 4 misfire.

Any ideas? At this point we are thinking we need to do a leak-down test.

What about o2 sensors? Like I said, I have eurocharged tune and cat-delete so I doubt o2’s would make a difference.


The only other thing I’m doing right now (which I should have done overnight) is leaving the battery unplugged trying to reset the ECU. I read somewhere in this forum that when we plug the brake booster port and getting codes to unplug the battery. I’m doubtful, but I’m giving it shot.

 

UPDATE:

unplugged the upstream o2 sensors, the one of the right we suspected might have been bad which was the bank I was getting all those misfires on. And the misfires went away! Took it on a 30 min test drive and it ran smooth the entire time. Obviously CEL is on for upstream o2 sensors not being plugged in and it’s running rich. But the car runs! Bad o2 sensor of all things. smh, what a run around.

 

woooooooooooooooooooooooooow

 

Damn man, amazing the effect that O2 sensor has. Thinks for the updates, I'm sure this will help others whom may have a similar issue. Cheers!

 

Glad you found it., I wouldn't have thought of that.

 

I should also mention, because I didn’t find it on the forum easily. The eurocharged tune, at least my tune, downstream o2’s are definitely disabled (no reading of live data) but we still could get upstream o2 data. Two days ago went we went to check live data of the o2’s the value was static at “1” for both o2’s so we assumed the tune disabled upstream o2’s and was preventing live data. WRONG. Last night, we tried reading values again and notice when the CEL was solid values for both o2’s varied but the right back o2’s (also were I was having all those misfires) was different from the left, sometimes by a lot.

Ive attached video of the live data readings, the last two lines (608/610 as listed on the left side of the screen in the video) are the o2 reading. The second from the last line (608) is the right bank.

 

O2 sensors are a big piece of the puzzle and are dead well before making the car non-drivable!

I have solved many odd issues by replacing one or more of them. Virtually every case without a code for a failure.

 

Exactly my experience, replaced both of my main O2s recently, definitely made an all round improvent