Hey guys, I have an 04 E55 and have been having issues with the car stalling when coming to a stop and stuttering when pressing the gas. For the last week or so, whenever I press the gas pedal enough for the car to downshift, it shudders and refuses to accelerate. Feels like one of those videos where people are revving their engines and shooting flames out the back. It bucks and stutters until you take your foot off the gas and usually does not drop a gear. This morning I even got it to happen in manual mode, but it’s almost always when auto downshifting. Manual downshifting always works.

The last two mornings, when coming to a stop at a light going to work the car has shut off. It’ll start up right after I put it in park, and the engine is just about at operating temp at that point (also it’s 17F here). This morning when it happened, I noticed it struggled with every downshift and could not catch an idle until it went to 1st and then just died. Again zero problems starting again so doesn’t sound like CPS.

I am between transmission problems, fuel, and CPS. Now that it’s happened in manual mode I don’t think it’s the trans. I do have the fuel pump leak occasionally when filled above 3/4 tank, but no other signs as most times I can gun it and it works great. And I don’t have any problems starting the car, so most likely not CPS.
Regardless, I have a CPS coming tonight and I have the trans dipstick though it seems like that’s a week long process to use.


I do have STAR. I’ve gotten idle speed control and pressure sensor codes, but my purge line likes to come off. The purge line is attached with hose clamps now.

Any ideas?

 

Also want to mention that after I restart the car from stalling, everything works like normal. I can give it gas without any idle or stalling problems.

 

Look for a vacuum leak. A lot of times when you shut car off and restart the ECU kind of go's back to normal until it sees an issue then has a fit.
Check the purge rubber line that comes off the steel line behind the supercharger.
Not CPS.
Check fuel pressure as well and see where it is at,you never know.

 

okay that’s good to know for the ecu resetting. That purge line is still good. Replaced it with a smaller ID fuel line and hose clamped it on both ends. The steel like is solid in the supercharger as well. I did have the vent line from the valve covers unplugged from looking last time, but I plugged that back in last night and it stalled again. I’ll see if I can get some sort of smoke machine for a vacuum leak.

As for fuel pressure, just hook a gauge up to something under the rear seat? I’m guessing that’s more useful to monitor while driving than just idle.

 

Sounds like the throttle body needs attention. The deposits are causing the problem. Get a can of throttle cleaner, and a few sheets of paper towels (blue type). Once you take it out and clean, let it dry over night. Reinstall, and happy motoring.
R,
2Merks

 

will do! Did anything in particular pop out at you saying throttle body? Just want to know for the future. This is my first car that’s ever had any problems lol.

 

Yes me..I was having the same problems/issues as noted. Chatted w/my indy and he referred me to check it out, so I did exacty that. Purchased a can of throttle body spary $3.45, and the tuff blue paper towel (2) pack $3.60 from walmart. Word of note..I did not spary down the hole, only the on towel and wiped really thorough...opening and closing the flap. I let it dried overnight, and covered the hole with cloth so nothing would fall/wonder in. That was about Mar of '23, and have not had any issues since. GL
R,
2Merks

 

Could be vacuum leak, could be throttle body. Could be fuel pump, could be fuel filter. These are the easiest things.
#1 I would replace the fuel filter anyway if it hasn't been done at least a few times. Its a maintenance item
#2 Clean throttle body. Its a maintenance item just like the fuel filter
#3 Check for leaks

At this age you most likely have at least a few small vacuum leaks. Hoses get brittle over time. Just one of those things
Really no way to find them without a smoke machine. I got a made in US smoke machine for around $70. They arent expensive, and if you drive an old car, its just one of those things you need.

 

Attach a fuel pressure gauge on the Schraeder valve on the fuel rail. Located passenger side front; looks like a bicycle tire valve.

 

This may help Pelican parts - under project photos

 

got it. I’ll get a gauge there and compare to acceptable values. My issue is that it only causes problems when driving (and I guess at idle so maybe I pull off after it starts)- so I may have to figure out how to monitor during a drive

 

Thanks for the how to- that helps a lot. Smoke machine is on order and I’m picking up some cleaner and a gauge tonight!

 

that is reassuring. I’ll clean it tonight if my fingers don’t freeze off. May just remove the throttle body so it’s easier

 

I have a fog machine on order and am getting a gauge tonight. Going to clean out the throttle body as well.
As for the fuel filter- I read through forms from people 5-10hrs ago who suggested there was an aftermarket fuel filter you could get that fits right into the housing instead of having to buy the whole $700+ setup. Do you know what filter that is if it’s a thing? The most I could find is someone saying they made a thread for it, but couldn’t find the thread on their profile.

 

If you have to replace the fuel filter, do the whole kit and kaboodle. Seriously. Expensive but you eliminate any potential issues from overlooked parts or broken lines. And the cost for fuel filter/pressure regulator plus dual fuel pumps is approximately $1000. Now is the time to decide if you can afford and want an E55 AMG. I'm not being cruel; I'm being realistic for you. An AMG is an expensive car to maintain. I've learned this lesson over and over and over again through the years...
If you really want the AMG, and are willing to pay for it by performing as much work as you can yourself to save the labor charges from the shop, go for it!
FWIW, the filter is available from Creative Steel if you decide to attempt filter replacement only. The fuel filter/regulator top is very difficult to rotate so you will most likely need a vise. I recommend silicon lube on the o-ring when you reassemble the top to the bottom.
Best to you. Seriously.

 

yeah I gotcha you make a good point. Definitely not bringing it anywhere though I can do it myself. Got the pressure gauge a little bit ago so I’ll hook that up tomorrow and see if it’s fuel at all.
Thanks for the tip for the filter only. It does occasionally leak when filling full so I’ll end up doing the whole job if it is fuel related. If not I’m due for a filter change so might see how far I get with just the filter. Hard to swallow but part of the life.
That is a funny smiley LOL!

 

He is right. The good news, the car is 20 years old and there is no more depreciation. Your car will appreciate from now on.
The bad news. Repairs are going to cost you. You either lose money with depreciation or with repairs. There is just no other way, but usually repairs wont be close to the depreciation on the car. Especially if you do it yourself.
That car used to be about 80k in 2003, around $140k in todays money. You will never spend that in repairs

As for the pumps, they are 20 years old. They are closer to the end of their lives than the beginning.

Also, better to use OEM stuff if its a big job. If its 30 min and it doesnt work out, replace the part again. If its many hours, just pay the extra for OEM stuff. It lasted 20 years, will last another 20 years.
Parts are also getting scarcer the older these cars get. You might be able to find something today, especially OEM and in a year or two its gone.

 

@SICAMG @dub108
I am at 70-72psi at idle (bounces between them), and after turning the car off and key cycling it is holding 54psi for 30 mins and counting.

I have to google more but seems low on both pressures. 78+-2psi at idle, right?

 

It's high enough where the engine should run smooth.
I would think you should see a code in the ECU at this point though.
If you just start the car it will idle fine?
When you rev it up does it come back to idle?

 

I’ll have to check it a few more times. No codes for fuel pressure at all. It very much depends on how Mother Nature is feeling at the time. This morning, it ran fine for 25 mins then the last 10 mins to work it stumbled around and couldn’t find idle. Started it up after work and zero issues though felt sluggish. Yesterday it was terrible from 2 minutes into driving until it stalled, then zero issues after restarting.

After starting it generally idles just fine. I start having issues after driving. And then coming to a stop. It’ll let the rpms get too low then have a hard time staying alive. RPMs return to normal after revving and it’s in a good mood. Does that make you think vacuum/MAF?

 

When it is stumbling it would be good to know your fuel trims as well.
The fact that it ran well for 25 min. and then acted up tells me it is not a vacuum leak because your problem would always be there.
If the event happens and you where to pull over, turn engine off and then restart is it back to normal? So technically you can just keep pulling over and restarting the car and keep going?
Just trying to get a handle on exactly what is going on....not that you don't know what's happening but conveying the information sometimes gets diluted a little in peoples description.

 

all good! It’s kind of confusing and yeah I’m sure it all gets mixed together. I’ll see if star can log trims or if I get some kind of normal obd2 logger tomorrow. If I pull over and restart the car it generally has no problems for the whole drive- sometimes it does come back but it takes a while. Didn’t have any problems restarting the car after those two times it stalled.

I have done that before where it starts to stumble, so at a stop light I restart and then I no longer have any problems. Makes it very difficult to troubleshoot. I’ll get working on the fuel trim logs

 

Star can monitor your trims.

 

Im leaning towards a MAP sensor bugging out at this point since it goes back to normal when key is cycled and then PCM see's an issue again. But trims will for sure be wonky when it acts up.

 

@Orznick14 if you find you need a MAP sensor I happen to have a couple of new ones that I can pass one on to you for the cost of a shipping label. Send me a private message for details if interested.