Dynamometer Test Confusion and Frustration
 

In connection with my chip tuning, I wanted to do before and after tests on a dynamometer. (I should say that, a couple of months ago, I knew ABSOLUTELY nothing about dyno tests...now I know just a wee bit more! :)) As I looked into the matter, I learned about needing to put the car in dyno mode to completely disable the traction control and that simply turning ESP off would not accomplish that. The issue arises because of the wheel speed differential on some dynos.

However, the dyno shop that I used has a dyno (it's a Mustang AWD 500) where the front and rear rollers spin at exactly the same speed; so that, as far as the car is concerned, it's as if it's driving on the road. So, based on my conversation with the proprietor, I concluded that putting the car in dyno mode was a non issue.

When I took the car for the first test, the tech put the car facing forward on the dyno and the car wouldn't move....he couldn't explain why. So, he then put the car on facing backward and it ran fine. He was able to do three pulls without incident.

Then I brought the car back after the chip tune. Still not knowing why the test wouldn't work with the car facing forward, he put the car on facing backward and it wouldn't work. Then he tried facing forward and it still wouldn't work. At that point he concluded that he wouldn't be able to do the test.

He explained to me that he's done tests on all sorts of cars, including Mercedes newer than mine, and he's never had this sort of a problem. So, he's frustrated that he's wasted an hour of his time with my car with its inexplicable quirk....and I'm of course frustrated that I can't get a second test done on the same dyno.

While I'm quite certain that I'm not exactly his favorite customer, he is willing to try the test again provided that I (a) pay up front and (b) figure out what needs to be done differently with my car. It makes no sense for me to go to another shop because it would be a different dyno with a different set of variables.

Does anyone have any insights or suggestions? Thanks so much!

David, as I sent via email previously... you gotta disable ASR/ESP manually in order to properly dyno the car. I don't know why it worked backwards the first time.

:scooter:

What do you mean the car wouldn't move? If your car was on the dyno, it better not move. If it moved, it would have gone through the walls or the door.:D

Did you mean your wheels did not spin?

Yes, but that was my point about this particular dyno....if the rollers are moving at EXACTLY the same speed, then the traction control issue should be moot. What am I missing?

That SHOULD be a moot point, if front & rear are moving at identical speeds. My guess is, they are not, although they may look like it. If the computer senses X% deviation, it spoils the party. Best way is to disable traction control and then it won't matter. Should be a 2 minute job to jumper pin 1+6, but please verify that elsewhere before attempting... it's been a while since I did this and I don't recall the details.

:batman:

I don't have much AWD dyno experience though I did dyno testing for a living for over 31 years. However, my sister-in-law is really up to speed on this stuff so I'll send her a note - she likely has an answer or can contact her connections at Mustang and see what the issue is. She is still working in the field and pretty much knows everyone who works with this stuff in industrial settings.

Dan

Yes, wheels would not spin.

Thanks, Dan....would be glad to hear any insights she has.

While I was at the shop, the tech called Mustang tech support to see if they could resolve the problem and they were stumped.

That sounds like a logical next step. I'm still confused by (a) why the test worked the first time (again, three pulls without incident) and (b) why he has not had a problem with other and nertw MBs (I take him at his word on this).

I think I'm missing something here... Is the dyno pulling data from the car's computer and somehow that is causing the car to not move? or does the dyno pull data from electronics attached to the rollers?

If the latter then...how does the car not move?

:confused: lol

WIS says to connect pin 1+6 at the 38-pin diagnostic port under the hood. See attached PDF.

:chinese2:

The dyno pulls data from electronics attached to the rollers (I think). BUT my working assumption is that the reason that the car's wheels won't turn is something the CAR is sensing about its environment. Hence GSXR's point that what I needed to do was manually disable traction control. Still leaves unanswered questions, though.

Wonder if the car's data banks can be read at the time the car won't respond? The Germans are always thinking when they design these machines, I can tell you that.

Talked to another dyno shop. It sounds like, rollers working in tandem notwithstanding, what would need to be done is is just what GSXR says: manually disable the ABS and traction control. Apparently the system used on the W210 is early and somewhat finicky...which may explain why newer MBs have no problem on the Mustang dyno. As to why I was able to have the test work the first time, he said it had nothing to do with which direction the car was facing...he said the tech just got lucky in somehow throwing codes, disabling the system, and thus being able to do the pulls.

We need very specific information to solve this.

From your description, when the wheels were lowered onto the rollers the wheels remained at Zero RPM regardless of throttle opening. ( car would not move. . ) Is this the case?

For the ESP to take control, there has to be some rotation of the wheels.

Was each tire centered in the dyno rollers? ( RE This dyno uses a pair of rollers for each tire, one end might be trying to climb a roller causing a ratio issue. ) Adjusting dyno wheel base solves this.

Is there clutch between the two ends of dyno? Leaving it open would cause the problem.

Are the front and rear tires different sizes ( They might be the same sidewall size but different actual dimensions, something that is pretty common. )

As far as I could tell, as he slightly applied throttle, the wheels would not spin at all, but they would "lean" forward a bit as if trying to move but then prevented from moving by brakes.

As far as I could tell, the tires were centered...and I'm assuming that, as the shop uses this dyno all the time, they would encounter this issue with other cars.

As to the clutch, I do not know.

Tires are all the same: brand new Michelin Primacy MXV4.

Note sent to the SIL.

All I'm coming up with so far is that the wheelbase is not properly set, putting an uneven load on each roll. We used to walk-in the car to center it without using any power (dyno or car) but I don't know if the Mustang AWD will accommodate that.

BTW - don't assume that the dyno operator knows what he/she is doing. Most don't and have only minimal training. A local shop has a Mustang AWD dyno and the cell has a window onto the showroom. I can't believe some of the stuff I've seen their operators do! I'm guessing that they simply don't know any better. I've asked them about their calibration techniques and procedures and they look at me like my head is on fire. So there is a lot of mis-information and lack of information out there.

We'll see what the SIL has to say.

Dan

x2. I know nothing about dynos but I know ESP doesn't come into play until the wheels slip.

It has to be said so I'll say it - did someone check the park brake?

Sixto
MB-less

That reminds me. Make sure if they strap the car down with straps looped over the rear lower control arms, that the straps do not go over the parking brake cables... or that will engage the parking brake! Don't ask how I know. This is easy to check visually after they have the car tied down.


:shutup:

If your car was tipped forward OR backwards, the anti-towing feature would go into alarm/disable mode - at least the system on my '99 E300TD's would. My '99 had a selector switch on the center dashboard to disable the anti-towing device. Does your '98 have such a feature??

.......OR, over the half-shafts......:D

Another; it has to be said - did the driver's door get set in a position to not disable the car? I am going to go with a hunch the car outsmarted the dyno/dyno-tech. I'd see if he'd ever performed dyno on this or any other model MB, and had experience with them?

Shertex said that the dyno guy has done later-model M-Bs and has not had a problem.

I like your idea about tying down the half-shafts :D.

The dyno guy apparently has done some research of his own today...talking to various people....and believes that the best approach would be to pull the ABS fuse.

I don't think mine has the feature to disable it.

lol the anti anti-towing switch!

If your car has drive by wire, that might not work as the first step to reducing wheel spin is to close the throttle.

If this continues to be an issue, PM me the dyno owner's name and the location. My SIL can then contact her person at Mustang (a VP, I believe) and they can look up the SN and work from that. The software packages vary and so they need to work from their info on THAT particular dyno set-up.

Please keep us posted - I'm really curious.

Dan

I'll PM you with info right now.

Contact Jeff as well to see what prep he does to dyno E300s.

Sixto
MB-less

Or... to 100% disable traction control.. Go under the rear backseat on the left and unplug the module.. Hasta-lavista no more traction control until you connect it again.

You mean Rocketchip Jeff? When I asked him about it, he downplayed doing dyno tests, saying various factors will change the readings from test to test, especially on lower powered cars like mine....said best to drive the car and enjoy it. Might not be such bad advice.

It's quite apparent on the dash, if your's has it. Guess not.

The later W210s are definitely drive-by-wire - at least mine was. -As was questioned in another poster's post. His isn't at all as my '99 was, from his descriptions on at least one parameter check. Disabling one feature on the W210 through your method and others, in some cases disables another function as well.

You're not referring to the on/off for the ESP, are you? I have that.

Got my head stuck in my '99 E300. Disabling ESP through the module, disables ABS also so yes you are correct.

Once you start modding your car, there's no limit/end to it. YOLO

I cut my teeth on the '99 I bought new - to stay ahead of the warranty. ;)

No. There's a tow-disable/abling feature rocker button.

Sometimes I wish I still had the car.:o

Is that the circular port that's a part of the fuse box assembly?

The SIL is working on it.

Dan

In this whole thread, this is the best advice. You have a great car, and in your earlier posts you mentioned how well the car responded after the mod was done. Now let me be the devils advocate.....if you do get the dyno test done, and it does not show improvement, what is your next step? You could be "spinniing" your wheels for a long time, all the while missing the enjoyment of actually having a great vehicle to drive. Good luck

Thanks, Dan. It will be interesting to see what your SIL comes up with.

Part of the mild tension of the encounter were different senses as to who should be responsible for figuring this out. The tech clearly views me as having an odd, uncooperative car; and that if I want to have a dyno test run, I should figure out how to disable stuff beforehand. I'm not unsympathetic with his perspective. On other hand, I would think that, if I'm running a dyno shop, I should probably become familiar with different types of traction systems, etc. and have some sort of database that enables me to figure things out on the customer's behalf.

I agree with you. If I ran this shop I would see your car as a challenge and a way to add to my knowledge base. I wouldn't charge until I had a good run to charge you for. In the dyno business, sometimes you get the typical "gravy job" - bring in the kid's Honda and give him a number - and sometimes you have to actually THINK and work thru an issue. When a job like yours is done the shop knows more than it did before and that's how you get good.

My dyno guy didn't want to charge me until we had the Camaro (I was running a '78 Camaro with a 250" six at the time) to the point that it would do a pull. I took it to him 3 times before we had it sorted to the point that it would run well enough to actually make power and do a pull. I had to force a $20 on him for the preliminary work and he only charged me $60 for the hour when we did actual tuning. He just has a DynoJet (not the most sophisticated dyno) but he does well with it. He took the attitude that he was learning so it was worth his time - he hadn't done much six cylinder tuning and it turned out to be a challenge.

As far as the "drive it and love it" comments - I hear where they're coming from. But the dyno is a useful tool and it should let you know what you REALLY accomplished instead of what you THINK (or want to think) you accomplished. The other way to do that is to take your car to the track w/o the chip and run at least 3 runs (more are better) to get a new baseline then repeat the runs with the chip. Remember to correct for changing ambient conditions (there are programs to do that). I don't know where you're located but I suggest the ECTA track in Wilmington, Ohio (just don't exceed 140 w/o a roll cage). Your local drag strip will also give you a rough idea of the actual improvements. There are several calculators to translate top speed numbers into an estimate of HP.

Guys who say "my car makes 100 more HP with the new chip" but have no actual data are kidding themselves. The truth is that they have no idea how much HP they have and are likely taking the chip maker's word for it. There are SO many variables you can't believe it. Google for "SAE HP determination procedures" for a real eye-opener!

Dan

The pay up front bit seems to me he's more interested in being paid for his time, not a successful dyno run.

Good point. While I am interested in being able to quantify the gains to satisfy curiosity, I really could not be any happier with the car than I currently am.

In case anyone missed it, the solution was posted in a PDF file back in post #11 on this thread. Straight from the factory Mercedes documentation. I didn't hear it from by sister's best friend's brother's second cousin who saw it on Facebook on their phone. I confirmed it myself, on my W210 1997 E420 on the dyno. It works. Don't re-invent the wheel.

For those wondering, no, pushing the "ESP Off" button on the console won't work. There will be an engine rev limiter which prevents going to redline. The system MUST be fully disabled as described in the PDF in post #11. The "ESP Off" button should really be labeled "ESP Mostly Off", or "ESP Off with Side Effects", but I guess they figured the font would be too small.

As to the guy selling the software upgrade trying to tell you don't bother with the dyno... that would make me even more intent on the dyno results. Sounds like he's hoping you never find out the measured power gain is below what they claim. Only one way to find out. The "too many variables" is a bluff... the dyno system will automatically compensate for weather conditions. You'll need to make sure the engine/trans is somewhat similar temperatures and there were no other changes since the previous run (i.e., same wheels/tires, no other mechanical changes/upgrades to the motor, etc).


:batman:

Great find, and I agree 110% with the depictions you give RE: the chip programmer guy.

Sure enough, I jumpered 1 & 6 on the 38-pin port (simply used a short piece of wire that was snug) and got the ABS and ESP error messages on the display.

Still waiting on a reply from Holly (SIL). With the holiday there was no one to chat up at Mustang.

Sounds like you're on the right path by blocking out the AWD but I can't figure out why you would need to.

More to come.......

Dan

Getting a bit miffed at what I can only construe as the non-responsiveness of the dyno guy. He said that if I did the leg work to figure out how to disable all the traction control (well, GSXR did that for me) and if I paid him up front (which I'm happy to do), he would do the second test. Have sent two emails and left a voice mail....nothing. Maybe he's on vacation....maybe emails and voice mails aren't getting to him....maybe he's in the hospital....maybe he's dead. But PROBABLY he's simply ignoring me. I'd gladly go somewhere else....but the whole point of running the test is before and after on the same dyno.

Oh well....at least I'm thrilled with the performance of the car.

Dan, any word from your sister-in-law?