Nachtsturm

Good read! Thanks for the link.

Looking forward to your 1/4mi times come spring.

betrezra

OK Here's the result of resetting my car (disconn batt), then drive to/from work, using my new toy DAS:

My DashDaq was showing High LTFT's which would slowly creep up to 20/20 up to 21/21 on left/right bank..... but the limit of dashdaq it does not tell you what load range this occures.... so it just tells you the max LTFT......

So then you spend 5 bills on a DAS system see photo below to dig deeper into the conditions.... and per snap shot below you can see my adaptation in the low range matches what the dashdaq is saying.... 1.21......

Screen shot showing ACTUAL value.....



My po-boy MB workshop....






SO with all this said.... I need a little tech help -
q1 - If I had a vac leak I would have high LTFT's everywhere.... not just at lower range part throttle. And I've checked this motor over 10 times for any leaks.

q2 - This car was tuned @ 5000' above sealevel in the summer.... I'm now running at sealevel @ 35 Deg F in very good air....... I assume it's safe to say the tune IS affected by altitue and temp and air quality??????

q3 - This car has the kleemann fuel management unit..... which artificially raises the fuel pressure per reference boost.

From what I've datalogged it works per following rough values:

-17psi Manifold vac /// fuel press stock 56psi
-5psi Manifold vac (part throttle) /// fuel pressure begins to rise per FMU
0psi Man at ambient /// fmu is jacking fuel pressure up to 75psi
7.5psi of boost /// fmu jacks fuel pressure over 100psi

I can adjust the kleemann FMU to increase fuel pressure sooner... meaning it will start the fuel pressure ramp up @ say -8psi vac......

Is this how I'm supposed to tune out this low range part throttle lean spot..... OR do I need a new tune for my new conditions?

I'm at a loss here, and do not want to run this at the track until I'm sure I will not hurt the motor......

I must add the AFR via real-time Wideband readout in car is GOOD after I'm in boost.... per klee 11.7 -12.0.... BUT I must admit I can see a little lean spike at tip-in throttle going from cruise to the initial throttle tip-in..... AFR go up to 15.5+ right before the FMU kicks in.



Another shot of where the action happens




PS - you guys considering tinkering with your cars will really like the DAS system..... easy to use, and THE tool for diagnosing issues. Plus there is a nice section that show pictures of just about every system in the car.



The below diagram/printout shows the load ranges...... (this is for the V6, but I suspect the theory is same).....

http://www.google.com/url?sa=t&rct=j...DxYru26H5CM8dQ

Kevwood

Contacted a MBWorld member that has one for sale, just waiting to see if he can ship to to me in Dubai. Thanks for the link

betrezra

Got some tech help:
1. Try putting a couple turns into the FMU to richen up the tip-in throttle AFR.
2. Data-log the voltage after the resistor for the MAS.
- Make sure MAS voltage is not pegging out (over 4.7V).... may need to add bigger resistor.

PTE

Open it up with a small screw driver , It has a little adjustment screw . Check your calibration at 70* F not attached to the cars harness.

betrezra

OK so another update (btw this car is going to make me earn it)...
I hooked up a Volt-meter to my Mas circuit after the klee reostat..... to read MAS voltage real-time, which is a challenge but I got it done, and can you believe all 3 new Autohaux Bosch new MAS are out of spec?!!!
MAS 1 - 5.05 volts under max load accell
MAS 2 - 5.04 volts
MAS 3 - 5.01 volts
Per cory a properly working MAS will read up to 4.67-4.76 volts under full load.
Also checked the resistance of the klee adjustable reostat.... set @ 600ohms.
So I get to order a few new MAS's and find one that works.

NOTE - these Bosch Autohaux mas's may be just fine for a stock car..... but the demands of a blown car with p/p heads requires a Mass Air meter with very precise calibration... which BOSCH does not seem to do regularly.. so I get to do some trail/error.

If anyone wants these essentially NEW MAS inserts for cheap...... for their n/a car..... hit me up.... I bet they are fine for a mild car.

BAD MAS meters.....



Multimeter hooked up to MAS circuit after the klee rheostat:


are we having fun yet?

betrezra

Got 2 new MASS Air meters coming to try out.
I can't believe there isn't a good aftermarket solution for my MASS AIR METER!

The mustang guys get a plethora of options, with the ability to tune with air sample tubes, harness interceptor boxes.

Not fair

betrezra

A little MAS tech reading for you all
http://www.wellsve.com/sft503/Counterpoint3_2.pdf


And more yet..... this article says MAS is bad if reading over .8 volts at idle.... I'm reading 1.5volts at idle.....
http://www.jegs.com/s/tech-articles/EFI101.html

blackbenzz

This is interesting. Mine was also pegging 5V so I went to a bigger maf housing. I'd be interested to see what you find. You could also try split second or other maf controller

betrezra

BB - if i am still pegging the two NEW Mass Air Meters..... I may have to go to a bigger housing next. I obviously can't buy 12 $100 mas inserts at a time every time one of these MAS goes out, which we all know they are not the most stable units.

I'll never understand why a $70K amg product has such unreliable sensors..... MAS, CPS, etc.

OK back to parts changing, and thx for help.

ecampbell

Don't worry about it as AMG has 135K products with unreliable bits as well! When is your car going to be completed? A couple of us are looking for a private rental either mid Feb on the west coast or late Feb in Floriday.

betrezra

"When is your car going to be completed?"

Fabulous question!!!!!!

It is mechanically all put together...... but I'm weeding out this niggling tuning issue in which my MAS is pegging...... seems to have raised it's head in this cold sealevel air this winter. Hopefully I can find a MAS that will play nice with the ECU.

Better safe than sorry on something like this.... I don't want to rebuild this 33K mile motor with only 5K miles on the blower build.

More to come. A mid 11 sec pass at full street wgt with D/R's would make me happy.

ecampbell

Sounds like you are moving forward but I hear you on the engines. A complete failure on my 6.2 motor (i.e. new block etc.) would be in the region of 35K just for the engine plus cubic more bucks for the work being done... My program is coming together quite nice and should be done early Feb. With DR's we are hoping for 9.7 or 9.8.

betrezra

Ec - good luck.

BB - let me know how you changed to a larger MAS Meter..... can I simply plug the stock bosch mas sensor in a physically larger meter housing? Inquiring minds want to know.

ashutt

betrezra- when you stated the "article says MAS is bad if reading over .8 volts at idle.... I'm reading 1.5volts at idle..... " don't forget that the Kleemann resistor box is fooling your MAS to see a different value so that the car runs properly as modified. I am sure you already took this into account but if not, it may affect what your reading on the volts.

Tech-Tune

Yup

betrezra

TECH - do tell how I get that setup!!!!


After talking to BB, I'm starting to think my MAS meters are fine...... (how can 3 new ones all be bad....)..... and it's just a matter of my motor is making more power than this stock MASS AIR METER can support before pegging. If that is the case then I need a bigger MASS AIR METER? Right?

betrezra

Ashut - Yeah I got that the resistor is affecting the voltage the ECU sees.
I measured the voltage before and after the resistor at idle:
One reading is 1.5 volts
The 2nd is 1.4 volts.....

I'm using the lower voltage.

Another thing to confirm when I am measuring the MAS signal voltage the ground is referenced to the chassis. Is this correct, Or do I have to reference a ground in the MAS harness its-self or does it matter? I figure ground is ground right?

I'm just a parts-changer

Tech-Tune

The MAF housing is a 3.75" hollow aluminum tube (ID 3.5")
The MAF bung was purchased from ebay.

The elbow is off an SL550. It fits my 82mm TB perfectly, but had to bend the aluminum housing to an oval shape in order for it to fit the elbow.

This resolved my MAF max issue, it should remedy yours.

I have an extra bung and tube. Let me know if your interested

betrezra

So I measured the max OD of AL pipe that will fit inside my elbow and inside the y-pipe and I can get a 3.5" OD AL Pipe to fit.
My stock MAS inside ID is 3".


Here is some al tube stock:
http://www.ebay.com/itm/3-5-Aluminum...ht_1234wt_1398


LMK where you got that Mass Air Meter bung.

betrezra

These guys claim you can change the range of the MASS air meter for pulling the sensor out closer to the wall.

http://www.hptuners.com/forum/showthread.php?t=32165

I could put a spacer for the sensor and pull it out closer to the mas wall.

Kevwood

That's excellent info!

blackbenzz

Yes You just plug the MAF sensor itself into a bigger housing. I had my ECU retuned as well.



Nice setup! Hope everything is well and that monster of yours is still running strong Did you have to get retuned for the bigger MAF?
Yup, after I tried a couple MAFs I cranked that adjustable resister like a million times. Noticed it wasn't doing anything and just had a bigger housing made.
Yea thats fine. My voltage is just a bit lower at idle, nowhere near 0.8V. And don't worry, changing parts is more than alot of other people do. Most just write checks but where is the satisfaction in that?

betrezra

OK So my game plan:
1. I've got 2 new BOSCH MASS AIR METERS coming this weekend. I'll test them in my stock MAS housing, and if they both peg @ 5.05 then I'm 99.9999 sure my motor is just making too much HP now in this cold sealevel air for this stock 3" mas meter.

2. I'll begin codgering up a custom AL larger MAS Tube. Please advise your source for that nice al bosch MAS nipple. I checked ebay and google and only found the slot type. There was one bosch type but it was not elevated out to place the sensor in the middle of the tube.

Then per your input..... I'll have to retune this with the larger Mass AIR Housing because the larger tube will lower air velocity across the wire and make it think less air is coming in; however, same air is coming in..... so the tune will have to richened up to compensate. All this larger mas tube is doing is keeping the Mass in RANGE of 0-4.85 volts.

NOTE - this does not fix my original problem of the part load lower range adaptation values which are runnning 1.21/1/21. Perhaps my new tune will resolve that as well.

OH, and another thing I was thinking of testing..... tape off 50% of my air filters on each side on the fresh intake side...... to test if blocking off some air flow will pull my meter back in range. I'm guessing it will. Shardul also advised I could bolt the stock big pulley back on the blower to reduce air flow cap of motor to pull the HP back in range of the stock MAS.

But something about killing HP goes against my grain. And a pulley swap on the klee blower snout is not a simple task based on it's position.

SHOP WORK VS SELF WORK - thanks for the support. I started this project with the turn-key idea........ and I was guessing that by having a so-called "high-end" shop do this work, I would be fine. But guess what..... the same limitations that apply to a ford mechanic apply to a mb mechanic regarding committment to quality work, and following through. Just because the mech charges $200/hr vs $100/hr doesn't mean you'll get good service/quality work/etc.... it just means you'll pay more. I believe putting DAS systems in the hands of enthusiasts is a way of keeping shops honest, and your local MB dealership honest.

Ok back on track.

Thanks all for the help on this journey.

Tech-Tune

How funny, I'm fabricating a similar intake. I wanted to eliminate the stock Y pipe, being it seems to be restricting flow.

Yup, running strong with no issues (knocking on wood).
A re-tune was nessesary post larger MAF housing. I was having surging issues at low rpms.