norb

So I'm driving in a parking garage and open my pano roof to hear the engine, I know, I know, I'm a geek like that, but finally I feel the hesitation when I give it some gas that people are talking about, and it occurs during the dreaded chirp (my car has that now too), as soon as the chirp stops the super charger must engage. So the chirp causes the hesitation. I should be an MB tech!

Steve Clark

the chirp is just momentary slipping when the blower's clutch engages.Some chirp/some don't...coincidental to,but not the cause of your hesitation.At most,the chirp is a symptom.
As you said-"it occurs during the dreaded chirp"...Dreaded?.I've had a chirp since the first few days,and I smile when my chirp announces that a flood of torque just arrived.

mbprince

I've got hesitation and no chirp!!

MB Life

I have been hearing about this chirp for awhile now from the new E55 owners.
Is there no fix for it yet?
What has your MB service tech told you about fixing this problem.
Seems irritating.

Hope the 04 and 05 models dont have the same problems.

norb

Just to clarify, I didn't think I had the chirp till I heard it in the parking garage.

Steve, when the belt is chirping, its not grabbing, right? So then it stops chirping and engages. Hmmmm, could that explain the hesitation? Sounds like it to me.

stephens

The chirp occurs when the magnetic clutch on the supercharger engages. The hesitation is cause by a mapping problem as the car is suddenly going from a vaccum/no boost situation, to boost and the ECU/mapping tables have a problem coping with the sudden transition. Since upgrading the hesitation issue has turned into virtual whiplash under certain circumstances. The ECU throws an error code in my case saying that the car has moved out side of range for fuel corrections. This shouldl be resolved with part throttle remapping of the ECU.
Well this is my opinion anyway from the data I have seen.

norb

So you're saying the two aren't related?

onesixeight

Stephen...

The ECU code your car is throwing...Is it a malfunction that is displayed on the dash, or does it need to be hooked up the the STAR diagnosis computer? I wonder if my car is doing it too...but my service advisor says it's normal since the three other E55 cars that have come though does the same thing...

Kind of bothers me because my passengers notice it and usually give me hell about it! "My '04 XJR doesn't do that...why yours..." Oh well...

-Chris
'04 E55
'03 SL 500

jkrutch

The fact that we have these problems on a $80k car is sad. The '04 chirps..mine started at 2,200 miles. I still have mixed feelings about the new M5, but I am glad I put a deposit on one back in June of '03 just in case I end up liking it.

MB should be concerned about the chirp and should resolve it. Hesitation shouldn't exist as well.

stephens

The two are related, The chirp is the belt slipping as the magnetic SC clutch engages. The hesitation is caused by the same sudden change from an engine air/fueling perspective.
You should notice the problem gets worse in colder weather.
The error code in mine is only visible via dealer diagnostics, but the visibility of this with my car is increased because of a significant increase of boost the pulley produces. ie the problem is really compounded for me.
It is easy to resolve by MB not trying to save fuel and have the SC engaged full time, instead of havingn it coast at low rpm/load conditions.
Alternatively a remap of the ecu at part throttle/boost conditions should resolve the problem.

onesixeight

Interesting... Is it possible renntech or another chip tuner could fix this problem since it's very unlikely that MBUSA or MB would reprogram the fuel delivery. The fuel savings was probably needed to pass some EPA or ELEV standard.

-Chris

Steve Clark

chirp from a belt system?.It's NORMAL.
Any belt-drive system is designed to momentarily slip when a sudden load is appled.The engagement of the electric s/c clutch is nearly instant;if the belt didn't slip that little bit,parts would break.As to the noise/chirp caused by the brief slippage-some have it and some don't.The chirp is not a problem,nor does it cause whatever "hesitation"that you are sensing.
If you really want to exorcise the chirp,just disconnect the wire connector going to your s/c clutch....it's just beneath the plastic accessory belt shroud,below the pulley on the blower.I promise that you will no longer have "the chirp" assailing your delicate ears.

jkrutch

If its "normal" as you mention, then why do some have it and some don't? Also, for many of us it appears around 2k miles from what I have read on here. It isn't about delicate ears, its about perceived quality issues with a very expensive car and the fact that its annoying. It just "cheapens" the car in many of our opinions on here. I expect MB to do better.

I'm not bothered by the sound of the turbos whining on my 911 because every turbo makes that sweet sound.

stephens

I am having mine remapped next week. I do not guarantee it as a fix, it is till just a theory based on observtion and deduction at this stage.

onesixeight

stephen...

Are you having your car tuned in Australia? Is it individual tuning on a dyno specific to your car?

stephens

Yes the tuning is specific to my car. It has already been remapped on the dyno, but part throttle mapping has still not been done.

norb

I only surmized that the two are related because I got the hesitation and the chirp after passing 2500 miles. Before mine was perfect, not hesitation and not chirp.

I really am not harping about either, have you ever read a post on me complaining about it, I'm just saying the two may be related based on my experience.

And the AC compressor act very much like the supercharger as it disengages when not in use but I certainly don't hear a chirp when it comes on. So the chirp is abnormal.