crankbiscuit

Friends,

I've recently purchased a 2003 Mercedes E55 AMG. It's been running well for about 3 months now until last week. Initially, the car felt slow but it did seem to deliver the power of a supercharger-less V8 and hence I thought the supercharger is not working given the 50 degree C plus temperatures that the summer welcomes us with here (I live in UAE). However, the problem persisted even during the much cooler night time temperatures.

I took to the car to a mechanic who hooked it up with STAR and it returned no error codes. He ran quick tests and said all electronics seem to be working fine.

A day later, the car barely touches 4K rpm at WOTs. It jerks and rides like a crazy horse no matter how smoothly I go down on the throttle. I'm now starting to believe it never was the SC and is something else that's choking all the power of the car.

I can't trust the mechanics here. I've tried and they are useless. So pls try to help like I am 10.

I've attached a video which shows the cars response on a quick kick-down.

Elhonaz

Seems like heat soak...so this happens when the car get warm or a little warm?

Not when cold starting? Please make sure your IC pump is working. Monitor your IAT via a simple obd scanner tool and an app for example torque.

crankbiscuit

@Elhonaz thanks a lot for your prompt reply.

I doubt it is a heat soak because as I mentioned the SC wasn't running even at night when the temperature is around 35C (though the humidity is quite high if that has anything to do with it) . I do monitor the IATs, they reach a maximum of 75 degree C if the car is standing still with the engine running for a while (at night). I do have a BOSCH 10 pump installed about 50k kms ago.

Also, kindly look at the video I attached. Do you that is because of heat soaking? Shouldnt I at least get the power of a v8 regardless of the ambient temperature?

As for the cold start, I didn't touch the car again lest that I may screw it up bad. However, As I mentioned, I can confirm that the SC wasn't working at night even immediately after a cold start when I was driving the car before the Complete power loss condition it is now.

GatorMB

It should run decent without the SC at all just bland.

I bet the SC bypass valve is acting up if the SC is engaging @ 3k rpm.

for a test plug a 12v jumper to the SC @ idle. accelerate mild and report.

TPS, CPS, MAP are common or possible intake leak. Since star found no faults you will have to find out if the SC engages.

TheTherapist

It could be a combination of a couple of issues - first I would check your IC pump which will severely inhibit performance and also test for a possible intake leak.

Also check your ECU for corrosion if the hood has been left open for any time. This will create decreased performance (among other issues) and is a problem I have not really seen discussed in the AMG forums but is a known issue with BMW's. They refer to it as a "green-out" or something similar. I am only aware of it since it occurred with my E55 after the hood was left up for maintenance for a few weeks.

Good luck - sometimes trouble-shooting this platform can be frustrating - I speak from experience lol.

crankbiscuit

@GatorMB, thanks for you reply.

Did you try looking at the video I attached? That's the cars response on a quick kickdown on the throttle. A day before I made that video, WOTs would instantly bring the rpm up to 7k and give me acceleration I would expect from a V8 alone. Initially I thought the car was simply heat soaking and that's why the SC won't turn on. But now, forget the SC turning on, the car won't even jump up to high RPM's. It reaches a max of 4k rpm.

As for the TPS, CPS, and MAP...can you guide me on how I can check if these are working fine?

StarvingArtist

Have you got a cel yet? that's about how mine ran without a SC belt, and the light came on after a bit.

crankbiscuit

@TheTherapist,

IC pump was my first guess as well and also what it's what other local e55 owners suggested me to get checked.

But again, try to look at the video I attached. That's the cars response on a full WOT. It maxed out at 4k rpm. If the IC pump is bad I would expect the SC to remain off but at least the V8 to give me it's full power regardless of the temperature. Am I right??

crankbiscuit

@StarvingArtist,

Hi. No I see no lights in the dashboard (CEL or any other). And my SC belt seems fine (at least to me and I don't have much experience with this car). You think I should get it checked??

crankbiscuit

How do I do that?

StarvingArtist

Leave the belt on, check the wire to the SC clutch. I'm not really an expert, just guessing.

ForKyleigh

Heat soak would not limit the car to 4k rpm. It pulls timing but does not limit rpm. I can't watch the video for some reason, so I don't know that I have much more to add. But that is not heat soak! By crazy horse, do you think it is misfiring? It must not be, because you should get a check engine for that.

JoeJErnst

My guess is that your SC clutch is not engaging. I've driven mine home from the race track before with no SC belt and I can tell you without the SC it feels more like a wheezy little 4cyl than a NA 8cyl.

You need a simple OBDII reader that can show you real-time boost, timing, and IAT. That should reveal the problem.

vioilio

Remove your rear seat and check your fuel pumps. Both of them! Remove the connectors and see if you have any melted pins. If all looks normal then hook up fuel gauge to the fuel rail port and check your fuel pressure.

T9ja

I think I did a post on this sometime ago. I had similar experience with loss of power, and rev limiter not going pass 4k under full acceleration. Problem was solved in my own case. Check your fuse box under the hood. One of your 15 amp fuse is probably blown. I replaced mine, and power was back.

T9ja

Any luck?

GatorMB

Some good feedback here,
The MAP, CPS, TPS when failed will lodge a CEL (check engine light),

When they develop mechanical or sealing problems we get culprits. The Map drives the BP valve and likely contributes to fuel and ignition curve. sealing and intermediate response will degrade the input.
CPS is pure ignition and fuel pump trigger. A couple of leaky ignition wires will interfere with the mag reluctor input. normally the car becomes hard to start or no start.
TPS is the input for the throttle actuator. Often they fail in a specific range with no CEL. I use a high quality volt meter that reads in 0.01 volts. This can pick up flat spots in the range of the sensor.
To test the SC unplug it from the harness and apply 2 jumper wires to the SC coil. +12v and ground.

I can believe heat soak, it happens to NA engines. Find a infrared temp gun. (harbour freight) 30.00. or borrow a pyrometer. Heat soak would be noted on a hot not cold engine.
The duel fuel pump system slipped by me as I am not set up as such. Highly possible

hope this helps a few.

Cheers, Gator

crankbiscuit

Ladies and Gentlemen,

Firstly, tonnes of apologies for not replying earlier. I work off-shore and the past two hitches have been a disaster leaving me no time to work on my Benz. Nevertheless, the problem as it turned out was simple. Like @vioilio posted, the problem was burnt fuel pump connectors. I took the car to one of the local "mercedes expert" mechanics and surprisingly, he did seem to know his E55 quite well. He instantly pointed towards the problem and took a little less than 70 dollars in labor charges to replace it. The pump itself though ripped a tiny whole in my wallet (1k USD) but damn it was all worth it in the end. The car is once again a monster off its leash.

Thank you all very much for your help. Once again I apologize for not replying earlier I know some of you were curious to know what happened. If you would like to know more details about this fix and what n all I did before I got this problem discovered and fixed, let me know.

Thanks,

vioilio

Glad to help!

atoms

Great news and thanks for the followup!

khelawanb

My car is having the same exact symptoms. I've spend days looking for a vacuum leak. I will target the fuel pump this week.