To start, I purchased a 2006 SL65 AMG back in June of last year. I was super excited for it to arrive, but had not seen it in person . I immediately had buyers remorse, but thought what the heck, I'll make this a project car and not focus on my E55 as much. Fast forward to mid-December and I've removed the wrap that looked so good from a distance, repaired the wrecked front bumper that was covered by the wrap, cleaned out the smog pump bypass valves instead of replacing them, and the car has run great.




Then I was driving home from the gym and got a CEL. I ran the code when I got home and it was a P0335, crankshaft position sensor. Having replaced the one on my E55 I thought yeah, this will be easy. Then realizing how hard it would be to reach, I thought I might move around the intercoolers and make it more accessible. I also figured while I had the car apart, and being that the weather has sucked here in NC, I'd replace the valve cover gaskets and spark plugs. The history on the car said that the ignition coils were replaced at 74,000 miles, but it's 14,000 miles later and I've only put 3000 on the car since I've had it so why not give the plugs a refresh.

So I replaced the plugs, and valve cover gaskets, then fought for a few hours with hands that are way to big to reach the crank position sensor. PRO-TIP- Using a 1/4" drive and 1/4" E8 socket makes this SO much easier Low and behold after putting it all back together the car wouldn't start. I killed the starter battery that night, and immediately thought it was a faulty CPS . I decided to put the battery on the charger and order another new sensor. The next morning for giggles I went to start the car one last time, and it kicked right over. And now I have a back CPS...

But that isn't where the story ends because rather than doing the right thing and verifying that my intercoolers were still properly bled...I didn't disconnect them, but did remove the upper radiator hose creating a bubble somewhere...I got excited and decided to take the car for a test ride since it had been down for like three weeks. I let it start and warm up for a good 10 minutes before going down the street to my local Autozone to buy more coolant...just in case. I use the Torque app on my phone to monitor vitals and noticed that the intake air temp was slowly climbing above 100F, and although it would come down 10-15 degrees occasionally, it made its way to 180 before I noticed a slight coolant smell. Then all hell broke loose and as I pull into my driveway (thankfully) the coolant low message comes across and I have a new green pool in front of my house. Turns out the heater core bypass valve broke open and coolant decided to quickly evacuate.

I just received the new bypass valve today and will be installing it this evening, and then properly bleeding both the IC system and the standard cooling system. I am super lucky that the motor never had time to get close to getting too warm, but will make sure that everything is good to go and coolant is flowing before going down the road again.

I'll post updates over the next few days

Keep us posted!

Alright! So everything is up and running again minus the exhaust being completed. I drove it today without the mufflers (axle-back section really) on a trip to Raleigh and then back (roughly 300 miles round-trip). I wanted to make sure everything was in working order so I setup my tablet with the Torque app so that I could monitor temps on the drive as well. The car did great! I did notice two issues though-

1- Without the rear section of the exhaust I think I was having a problem with too much boost being built at 4000 rpm and full throttle, and the car would back fire and momentarily act like it hit fuel shut off. I assume this was the waste gate opening up to protect the motor... Once I get the mufflers finished I'll revisit this with fingers crossed it doesn't happen again.

2- The IATs while I was on the throttle in 45 F degree weather and cruising at 70 mph stayed at 107-115 F...until I hit traffic and everything heat soaked. I saw the temps spike at 160 F, but then would drop in the 120-135 F range once I was moving again. This afternoon I sat in traffic for 30 minutes in 70 F weather, and the temps went to 160-165F and took a MUCH longer time to drop, and never really went below 130F for the remainder of the 1.5 hour cruise home.

I was trying to keep everything stock on this car, well except for a tune, but am really thinking that a trunk tank, re-routed lines, new I/C pump, and bigger HE are the way to properly manage the massive temps this car experiences. It makes me wonder what temperatures other turbo cars (Mercs or not) with water to air inter-coolers experience in a normal day.

On the bright side, I did get an average of 19 mpg!

So what I said for my first problem was a little backwards... I'm thinking that there is a boost leak somewhere, and it's dumping power, but if you stay in it on accident it will keep building power until it shifts at around 5500. It's weird but I don't think it is due to the ignition coils and I don't have a CEL to go with the dreaded misfire problems.

the symptom does mimic an ignition coil issue

So I thought the same thing, but then read about how some people had issues with boost leak doing the same thing even after replacing the ignition coils. I've ordered t-clamps and new couplers that are 0.5" longer for the charge pipe to intercooler connection.

I should have prefaced that the coils on my car were replaced about 10,000 miles before I bought the car...and "should" be good...

Well, I hate leaving posts that go on with no resolution to them. I always get to the end of one where it seems like the person made the fix, but you never get confirmation.

I have not reached the end of my debacle, so I thought I'd give an update. I have put a few miles on the car, and wound up replacing the spark plugs...again. To my surprise, that wasn't the issue, and still I cannot get over 4200 rpms. So I ordered new insulators for the ignition coils, it is amazing that a $2.80 part winds up being $90 when you need 24 of them. I still wanted to replace the inexpensive stuff first before going into the big repairs. There are multiple reasons for me going this route rather than the new coil route:

1- No CEL has ever gone off indicating an ignition coil issue
2- I keep thinking that one of the coils may just be grounding out because on a cold start the motor will act like there is a slight load (drops maybe 50-100 rpms) on it after the cold start cycle, but it doesn't stick around.

So I got the insulators in the mail today, but too late! I killed the car last night on the way home from dinner with the wife. Thankfully it restarted, but I finally received a CEL. If you only knew how bad I've been wanting the CEL to go off, just so that I have a lead on the problem and can narrow it down. Also I was glad it restarted and got running again because when I got out of the parking lot I coasted into, a beautiful silver SL55 pulled up behind me...and we can't have an SL65 die around its little bro!

Anyways the CEL was for the original issue, a P0335: Crankshaft Position Sensor Circuit A failure. Yippee...So I thought something was wrong with the one that I ordered and put into the car back in January. After getting everything buttoned up, I could not get the car to restart even though the codes had all been cleared. I ordered another crank sensor that night because I was sure the new one that I had replaced went bad. But the next morning when the car started I thought maybe I had been mistaken. Well...turns out maybe it was bad all along and I should have just replaced it. At least now it won't be such a daunting task, and I know that I don't have to remove the intercoolers in order to reach it.

It will be a few weeks before I am back home to give it a go though. As soon as I get that one in there, I'll let you all know how it goes.

ignition coil problems don't always bring a CEL with them.

True.

I finally got the chance to replace the crank position sensor, and turns out that was the problem the whole time. Apparently the first one that I bought was bad. Now I'm finally able to run my girl at full song again