I'm not sure what to make of this. My numbers seem to be a little lower than most for a stock 55. Unfortunately, we didn't do the gas analysis so I'm not sure about the mix, but I've no reason to suspect it's wrong.

Thoughts??

 

Re-dyno it again, but this time do it in 4th gear and put up the A/F on the chart..

Cant tell what could be wrong from what you posted.

You can start by telling your dealer to do a code scan for bad intercooler pump and see if that has gone south on you.

 

Sorry to be ignorant but how do you know what gear the pull was in? Also, are you saying from just looking at the numbers that there is something wrong and that I don't just have a low hp engine? I went to have this done just to see where my output is and now I'm going to loose sleep wondering how I'm going to keep up with you lot. BTW, my dealer says that the ECU has not been reflashed however also says there is no open recall either

 

dynojet or inertial based?

 

dynojet

 

Nothing is wrong with your car.........the car makes 469hp at the crank.Subtract 19-20% for parasitis loss,you are right there in the ball park.Lots of people get different reading b/c of different dyno equiptment,altitude,temperature etc........take it to the track,even if your ET is lousy,your MPH will tell you if you have the power.

 

I know it was run in 3rd gear because a 4th gear pull would exceed 155mph at 5,400RPM at which point the ECU would cut fuel and your run would end. 3rd gear allows you to pull to redline but isnt a 1:1 transmission ratio so you wont get accurate numbers.

I also know by the smooth lines and no jagged transition points that the car was in dyno mode and it was run in M transmission mode. If dyno mode wasn't on, the ESP light would have been triggered and the graph would have very jagged up and down transition points. If it wasn't in M transmission mode then the car would automatically downshift to the lowest gear when your foot hit the kickdown button and you would see that on the graph.

Now, if you redo it in 4th and post it up with A/F it will be easier to diagnose what is wrong.

 

 

wow!!

 

Damn Vrus you have seen a ton of mercedes dyno graphs haven't you!

chuckle.

 

Jagged lines like these,or worse?

 

Just back from the dyno.....any thoughts??

 

Yeah - your O2 sensor data looks good . . .

 

That was very good.

 

Lee,

That looks about right for a stock car if you factor in the 18-20% loss at the wheels. You're putting down between 461-473hp.

 

Jim!! You crack me up!! YOU REALLY DO!

I Dont think I laughed out loud like this in a while!

Thanks for the pick-me-up!! ALTHOUGH.. I AM IN A MUCH BETTER MOOD NOW!!! (See 80mm TB Thread)..

 

A few.

Much worse. The power and torque lines would drop right down (in half or more) and then climb back up very quickly.

That graph looks more like either bad A/F and/or ECU pulling timing.

Kev,

I dont agree.. All stock cars are dynoing 410rwhp - 420rwhp and 460 - 470rwtq. He is down over 30rwhp and 30rwtq. That's big power difference for it to be considered within range.

Remember, ALL E55s are dynoing higher than the 469hp they are rated at.. My car did 411rwhp and 476rwtq and mine was on the low side for hp for stock cars.

Something is not right and he needs to check into it a bit more.

 

A/F was at 11.7 the entire pull.I was standing right next to the car and listening very closely to the motor for different things.At first I was trying to hear if the belt was slipping or drastic change in the rpms as they came up.Sure enough,the second pull(red)I could hear the motor take a nose dive at 3900-4400.Not sure what happened but I was thinking timing being pulled maybe due to IAT's or high water temps.The (red) pull was also back to back from the first one,no cooling of time.The last pull had a 13 minute gap between wher we had the fans on and a 20lb bag of ice sitting on top of the SC.It was very obvious from the sound of the motor that it was pulling harder on the last run,over the second pull.Im not sure why it made such low HP numbers but it seem the Tq was decent.The car runs a consistent and has only had the SC shut down on me once,Ive hooked the laptop and made a few hard runs to check IAT's and ECT's but they seemed ok.So it must be timing jumping around.

 

That's a weird A/F to have straight across the board.. I have yet to see an E55 with that kind of A/F curve on it... Are you sure the reading was accurate ??

I was going to say belt slip, but it is unlikely since the dip in power happened in the middle of the RPM band and then picked up again.. Most likely it is timing.. But, unless there is a misfire code in the ECU or your IAT went above 140F I dont think that should happen.

Could also be tire spin.. Was it a rainy day when you did the pull?

 

A/F could have been off,Im just going off what the guy told me.If the belt was slipping I would think it would of had a nice spike in the beginning of the pull,where the SC tried to catch up with the motor.It was a nice hot So. California day,no water and I didnt notice any tire residue on the ground or near the wheels.From the sound of the motor,it didnt really sound like it was coming alive until the last pull.That pull sounded very different than the rest.Im going to try another dyno place soon,maybe take it down to EvoSport,their close to me.Maybe I can get one of there late evening runs?Next time Im going to hook up my labtop and log the runs to see whats going on.

 

Just another thought.. I would pull the spark plugs and check them. You might have a problem there.

 

I got my wheels redone this morning with the correct conditions.

Vrus, you still think it's low? the A/F dropped below 10 which I was told was not measurable.

 

Dude, you should've called me and we can go together.

 

Your car is running a bit too rich.. You are at 11:1 through most of the RPM band.. Either the supercharger belt is slipping like crazy or the ECU is dumping fuel for some reason.

Open your hood, remove the plastic cover at the front of the engine and look for black dust on your pulleys, underside of the plastic cover.. Also check for belt wear on the edges.

It most likely is belt slip.


OR

You've got a car that was originally modified with pullies, headers, ECU and was put back to stock, but the P.O. left the modified ECU in it. Do you know the history of your car?

 

Vrus,

No I don't. I bought it with 10k on it and a year old. It did sit for about 6 months before I bought it so if the mods were done they would have been installed and removed before that.
I'll check for the dust.

Re: A/F what would you expect throughout the RPM band? I assume the flatter the better and certainly the dyno tech said that I was loosing it at high RPM.

You mentioned to Jrocket that it was unusual to see a completely flat A/F