david_d23

I took my stock '04 in for its first dyno today. Daddy was soo proud! Could you guys take a look? A few things to note. This dyno was done on a chassis dyno; the one that hooks up to the rear hubs. Also, the pulls were done in 3rd gear and in dyno mode. When they tried to run in 4th, they hit the limiter. I tried a spot with a rolling dyno, but they didn't have the tie down straps to keep the butt of the car with enough pressure down on the rollers. After 3500 RPM, the wheels rolled faster than the rollers and they couldn't get an accurate measurement.

Is my car slower than normal? I have had this question ever since I bought it. I and someone else test drove another E55 that felt faster than my car. When I punch it at higher speeds, my ESP light doesn't flash like others have quoted on this site.

Anyways, your opinion would be appreciated.

Thanks in advance to all who reply.

zoink

Looks very low to me.... and your torque curve seems very steep....

Typical stock E55 is 390-420whp & 450-480wtq.

ATKM5

IC Pump. My car only put down 375 whp and 442 rwtrq... until Victor helped me and told me that my pump is probably dead. MB replaced it and now its a beast.

komp55

Graph says numbers are at the flywheel, so they would be lower than at the rear wheels. I wonder what driveline loss factor they applied?

sang55

I think it depends on elevations too . Im over 8500 high elevations and I got 390whp , after K2 put on now I got 455WHP and 535WTQ

david_d23

Elevation should not be a problem. I live in northern VA and we are not high up. Also, I am not sure why the measurement says "at the flywheel". They did measure from the rear hubs, but I will call the place and find out.

For those that have had the IC pump replaced by MB, is the new one not plagued by the problems that the old one had? How do I convince my dealer that it is the pump? What exactly are the symptoms of a failed pump? I did hear my supercharger belt chirping like a canary throughout the test, so doesn't that mean the supercharger is engaging?

Thanks again for all the help.

jangy

A few things. I will say it again, ANYONE who claims crank power has about as much credibility as MBUSA marketing does. They rate the E55 at 469hp at the crank. Is it? Can you prove it? Then stop using CORRECTION factors!!!!

Correction factors, whatever they are used for, are simply a way to massage the numbers. Learn to work with raw numbers and conditions. Yes, there are more variables to track than just looking for peak numbers, but it is really insulting to see so many people waste money on a dyno run to get no valuable data out of it.

Now, as far as testing your pump. Just do a few blasts back to back. On the dyno, it will lose 10 - 20 hp per run, if you go back to back. The better the cooling, the longer it will maintian the power.

No disrespect to the OP, this is just my pet peeve. By the way, my car has 700 HP at the crank. I figure I'm close to 600 to the floor, and I sprayed the outside of my diff with WD - 40. By my calculations, that mod should reduce my drivetrain drag by a modest 5% and VOILA!!!! What? You disagree? Prove it. Until then, I have 700 at the crank.

Jakpro1

Awwww mannnn, belt slip. Tell dealer it's been squealing on you and have them replace. Had some guys be stunned at the difference a new belt can make. Don't call it chirp as they will confuse it for supercharger engagement chirp. Common problem on our cars.

If they won't replace it, buy a new one and have them install. Worth the hundred beans to try (belt plus 2 min install charge)

joshd

Just FYI, I think Dynapack printouts always say 'flywheel' even though the power is measured at the hubs. They do have some modes where it tries to estimate at the crank, but those numbers above are likely as measured at the hub.

Good luck with the dealer, they seem to be hit or miss (more often miss). I had the same issue as evidenced on the dyno and on the street to the point where my S/C would completely shut off after repeated full throttle romps. I told this to the dealer and had them 'check it out' and in the end they gave me my car back, did nothing, and wrote on the ticket (and I quote exactly):

'the s/c will shutoff when it's no longer needed'

Yeah ... so I just bought the cm-30 from LET Motorsport and paid an hour of labor to have it nicely installed ...

Here is my baseline dyno before the pump install FWIW: https://mbworld.org/forums/showthrea...432&highlight=

I had a similar falloff in power after 5K ... I also may be suffering belt slip in addition to the pump issue. I'm going to get a new belt to cover my bases and then schedule a re-dyno.

david_d23

If I get the dealer to install a new pump, will it fail again like the current one does? Is given the choice to go with the dealer pump vs. Johnson pump, which one is better? Will installing Johnson pump void the warranty?

joshd

They do seem to have a high rate of failure, although supposedly there is a new and improved version they are using now. The Johnson one flows a bit more and seems to be more reliable, I would choose it.

david_d23

Car is with dealer and has been for the last 2 days. I brought it in complaining of power loss and showed them the dyno results. Also told them that another 04 E55 owner and I swapped cars for a minute and his car drove faster and he thought my car felt slower. All of this and they tell me that the tech says the car drives fine.

I asked if they had another E55 they could drive to compare and the SA is looking into it.

Any advice on how to get them to take this seriously? I already mentioned the IC pump as a possibility and the SA still came back with "nothing wrong".

weber1

How long do these OEM pumps typically last? I have 18,000 on my 03 E55 and I havn't noticed any let down in performance but then again I bought it with 12,000 miles and may just not know any difference. I was thinking about bringing it to the dealer but expect they will tell me the pump is fine.

david_d23

SM and SA denied doing any repair. Also told me supercharger chirp was normal.

ChicagoX

I got the song-and-dance as well, at first.

Try mentioning a lunge, surge, or rough engagement of the Kompressor. That they had a TSB for, and were willing to fix. No more chirp.

You should get a Johnson pump anyway. The OEM ones can fail without warning, even with low miles.

weber1

Will MB install a Johnson Pump? Want to avoid voiding my warranty. I just figured if they did it then it wouldn't be an issue. I tried the surge/rough engagement last time I had it in for service and they said everything checked out fine. oh well

ChicagoX

It's an easy DIY for those so inclined, or any Euro shop should b able to do it in about an hour.

It took 3 tries to get a fix for my chirp/surge, so keep hammering them.

david_d23

Well, the dealer has since replaced the I/C pump and I have replaced the S/C belt....it was of little help to my power loss woes.

I have purchased a data logger (autoenginuity). Anyone have any tips on what to monitor?

joshd

Timing - check for it being pulled back (going lower) when there is a power loss - and Intake Air Temps are a good place to start I would think.

david_d23

I checked IAT's and they ranged between 90-120 F

rflow306

Are you checking them at wot for two to three gear changes?

RAVEN_CTS-V

It would be nice to have another 55 dyno on the same dyno. You're making a lot of assumptions based on one dyno readout and your SOTP meter by driving another car.

MB_Forever

I'm confused.......... so is your dyno an estimated figure of what the car is making at the crank or is that dyno showing rear wheel hp? Do you have un-corrected graphs?

Regarding the IC Pump, it is a common problem with the E55s. Mercedes had Bosch design a newer IC pump as a replacement for the original one, but I've heard people saying that although it's a little better, it still fails often. I would purchase a Johnson Pump, as it seems like a much tougher version (less fail prone) than the factory one.

RAVEN_CTS-V

I believe that all DynoPack graphs state flywheel even though it is measuring the output at the wheels. Although, I don't know why they would do that - it is confusing.

waxking1

Dyno result seem to vary quite a bit. I think the best way to test your car is to take it to the track. If there is something wrong, you will see it on the timeslip.