Hi all,
I have a 2011 E63 AMG that starting showing signs of a hard start / prolonged crank (Prolonged crank, and hesitant start). Here are the observations:

Only happens when the car has been sitting for longer than an hour or two (It's kinda cold out). If I got back to the car, say 10 minutes after I drive, it starts perfect.
Crank is fast, and usually, after it starts the first time, the second time, third..etc seems totally normal. Always the first crank after an hour or sitting down that is problematic.
I can hear the fuel pump start when the keyless is in position 2. I've tried to cycle position 2 a few times before start, seems to help a bit, but no strong evidence. Still not a perfect start.
Car drives totally normal, under full throttle and normal driving - no signs of loss of power or anything else

I am thinking it's either the CPS, Fuel pump, or something related to fuel pressure....

I am usually very good with diagnosing car issues, or working on cars, and this has baffled me...

Can anyone with more experience with this engine help me diagnose this?
thanks!!

 

Start with the simple stuff: battery. How old is it? And, have you had it tested?

 

Battery is about 1.5 years old and seems to run just fine.
there are no signs of a weak, or slow crank...lights and other interior stuff seem ok. I have no tested it.

 

Issues like this are always thankless tasks to try and tackle. Seeing as I've got a 2010, i'm going to subscribe and try to help where possible so that we can find a solution to your issue.

First things first - you're going to need a data logger of some sorts. It's super useful when dealing with a modern car so you should have one anyway. Even if you just get a cheapo Bluetooth dongle from eBay and then download the Torque app for your mobile phone that'll be a good start. You'll then be able to read error codes, find out your fuel pressure and idle vacuum - knowing those three from the outset will help you to rule out digging down the wrong hole.

 

Thanks! I do have an OBDII Bluetooth and I don't see any codes or any issues.
I have not tested my fuel pressure yet..can't find the fuel line.

I tested the battery a little bit ago at advance auto parts. Showed voltage of 12.39 And a low charge...which might be because I've been crank testing it?? They recharged battery inside and went back to 12.7 and the car cranked perfect. I'll let it cool and try again...would a 0.3 difference in voltage make it crank so poorly?

I bought a CPS, was going to replace it while they recharged the battery but I got stuck not being able to locate the clips holding the Y pipe in the back of the engine...

I'll provide updates...but not I'm even more confused with the battery situation.

thanks

 

Ahhh good stuff. I'll pp out now and check my cars fuel pressure with the key on click 2 and report back.

If you want to manually connect a gauge to the fuel rail, you can find it by removing the airboxes. The right side of it has the fuel pressure sensor harness and I think on the left side of the rail you'll see a gold nut - presumably for connecting a threaded gauge to?

Your voltage is good, I wouldn't worry about it. lol if anything, it just highlights that I need to replace mine before I'm left stranded. Mine sits at around 11.8 or so and cranks ok....but I know, I'm pushing my luck. Your 12.4 on a bad day is plenty strong. And in any case, it's not a weak or slow crank as you said - it's a hard start, so it won't be the battery. Glad we've ruled that one out for the moment.

At least you have the CPS....if it's not a vacuum leak, then the CPS is a very good candidate tbh. You say it drives fine, so let's say it's probably not a vac leak for the moment...one of those would give you a deep bellow at idle.

The clips for the Y-pipe thing. I used to struggle too. I can do it now in 3 seconds. I sit on the engine (I'm tiny) and use my left hand to poke down the gap to aim for the clip that's on the right side of the motor (driverside for you guys). I reach to the bottom of the clip and press it outwards...you should feel that side of the pipe lift up (oh btw, before doing this, quickly lift the airboxes upwards to remove them from their rubber seats). Once the Y-pipe is unseated from that side, apply some pressure to the assembly and pull it towards the left side....you should feel that clip pop off and be able to wriggle it up and out (don't forget to unclip the maf harnesses and the little black rubber pipe).

I've heard the CPS is somewhere back there when you take off the intake manifold for easier access...please post pics and updates when you do this.

 

Yep not battery. Just did it again...can you please take a picture of the clips location? Can't find them!

 

Guys,
I was able to remove the ypipe...but there is no way on earth I could reach the CPS... but I connected the OBDII and pulled up the fuel pressure gauge..And I think I found the issue. Upon ignition, the fuel pressure goes up to 60 but quickly drops to 30 or lower. When the car starts, it maintains 50+ pressure.
so that leads to the next question, is it the pump or the regulator? Does our car have a fuel pressure regulator?
also...another strange thing is when I put back all the intake system together...I got a CEL, I thought it would be the MAF sensor, instead I got P228C - low fuel pressure.
any help is appreciated!

 

I'll check mine for you tomorrow man (it's 1am here and I'm about to K.O.)

Regarding the CEL, double-check that you didn't accidentally trap the black bendy hose under the Y-pipe and create a vac leak.

If you don't hear from me in 12 hours, bump the thread

 

Thanks man! Happy New Year. CEL is gone..so probably related to the disconnected MAF...

 

Here you go my friend - around 65psi with the key turned to one click (same pressure when on key position 2) and then around 50-52psi with the engine running.

I selected the fuel rail pressure display on the Torque app, but it doesn't provide data for our engines - ignore this display.

Engine off - ignition key position 1:




Engine running





Happy new year to you too

 

Thanks!
I get the reading 60+ when in key position 2..but then I just watch it drop to 20. Does yours stay constant at 60+?

when engine is a running a get a constant 52

thank you! I'm using the same app!

 

Yeah it stayed at 60+, although i think i was only watching it for about.....30 seconds or so. Not sure if you waited longer than that to see it drop to 20? Perhaps this might be the issue then (compounded by the hint of the CEL with the low fuel pressure warning).

Try the pending codes stored by the ecu...i wonder if that has anything useful to share.

 

Mine drops within seconds. 30 seconds is plenty enough! Thank you. I guess my question is to everyone, is what causes the fuel pressure to drop so quickly? Could be a leak or fuel pump valve? Do our cars have a fuel pressure regulator?
thanks

 

Hi everyone,
Just wanted to update that I found the issue to be the check valve (Fuel regulator) in the fuel pump. I just prime the pump before starting the car and it works every time.
I took it to benz to see which fuel pump would need to be replaced, and they didn't know so they said replace both for $1600. I do not want to do that. Any ideas on where the fuel regulator is? left or right fuel pump?

I am noticing dark smoke out of the exhaust under VERY hard acceleration (Like one puff everytime)..(I don't see it when I drive, but when someone else is driving my car I notice it., and from googling that, it's potentially unburnt fuel and could be caused by having a bad fuel regulator..

Let me know what you guys know or think, I want to order a new fuel pump and they're 300 each, I'd rather find the right one than replace both.

also, is it worth checking my fuel injectors for leaks before I do this?

 

Let first go on the record and say you are one hell of a stubborn man. Holy wow!!! Damned near 2 years before taking it to a dealer? Not sure if I should be impressed or scared.

As far as their recommendation to replace both, it's actually a good one. Alternatively, yes you can go about individually diagnosing the pumps but it would take more time and effort than it would to replace them. I get the impression you're going to do it yourself. If you feel capable and competent enough, that's your cheapest bet.

If you don't trust this diagnosis, take it elsewhere.

Regarding your injectors, unless there's something leading you to believe there's an issue with them, leave them alone.

 

Hahaah, I actually took it to the dealer a long time ago and paid them to diagnose the issue and they came back with a $1600 bill and no guarantee that it would solve it. I left the issue for 2 years because I just primed the pump before starting it and I've never had an issue but now that I've noticed black smoke under hard acceleration.. I've decided to try and do it myself. I am very capable of replacing the pump, I was hoping one of you knew which pump had a regularator and which one didn't. Why do you think replacing both pumps is a good idea?
Thanks for the response!

 

If it's really been that long since the original diagnosis, and you are now noticing new symptoms, it would be worth having the car looked over again. It could be the same issue, same issue worsening, or a newly developing issue. Hard to tell and diagnose over the internet without significantly more information.

 

I'm experiencing the same starting issues with my 2010. I've had the battery tested as well

 

I would check your injectors sounds like you have a leaking injector that’s leaking down pressure and causing hard start issues. Enough leak down could possible wash your cylinder out. Check your oil by pulling the dipstick and smelling the oil to see if you can smell a hint of fuel in oil. If so might need to have it checked out cause enough fuel in cylinder could possible bend a con-rod and cause greater damage.

 

That was my fear! Its been going on for two years and the tech at MB said a leaking injector would throw a code and I would feel it while driving. I'll probably check it in a few weeks.. just got done with valve cover gaskets and I am exhausted!

 

Yes, it could possible set a code for rich condition if the ecm doesn’t auto correct by trimming fuel back on other cylinders injectors, lets assume that number 2 injector is leaking fuel into the cylinder maybe not enough to set a hard fault for faulty injector cause its not an electrical problem but a mechanical seal problem in the injector, ecm sees a rich condition and trims back injector pulse width enough to accommodate for maybe engine wear and/or maybe bad air filter on that side. A cylinder contribution test, or maybe pulling the plugs and bore scoping the cylinder and getting an idea of the cylinder condition. Removing the injectors with rail shouldn’t be that hard, remove rail with injectors and lay them on the intake manifold and turn the key to the on position the pump should prime if the injector is leaking it will spray. Fuel grade in Europe is far better and cleaner than US grade fuel, better atomizations from superior injectors means tighter tolerances which means high performance injectors will suffer from impurities in US fuel.

 

Most manufactures give a standard time for bleed down 30 seconds to bleed down to given spec. The fuel pump will try to maintain given pressure while engine is running. So if your injector is leaking fuel management system will run pump freq to maintain given fuel pressure.

 

look at this post

 

Great video!!

Question: During this test, engine is on or Off ?

I dont hear engine running but clicking sound.