Would it make sense that this is infact some sort of electrics problem as the MAF keeps dropping out to 0? It seems that there would still be some air drawn through the MAF even with a large intake leak.
Would it make sense that this is infact some sort of electrics problem as the MAF keeps dropping out to 0? It seems that there would still be some air drawn through the MAF even with a large intake leak.
Or something messed up in the software.Originally Posted by UrS6
Other possibility would be reverse flow through MAF. It could happen if something's wrong with wastegate or bypass controls (turbos badly out of sync, etc).
Just my 2 cents, I'd agree that it sounds more like an electrical problem than a vacuum leak. Any chance you could extend the good side wire far enough to plug it into a MAF on the "bad" side? See if the readings are still low? I don't think the wire harness is long enough but it shouldn't be too hard to rig up an extension harness.
RS6 #1, 01E, 2.5" straight pipes, AMD Stage 1 6MT tune, 460awhp/530awtq on AMD's Mustang dyno. TOTALLED.. RS6 #2, Ebony Black Pearl on black/silver combination with carbon, up and running with 6 gears and AMD tune.
Software seems unlikely. How do you check the wastegates? Pressure to the hoses off the n75? I think the passenger side WG Rod was being held up by an oil tube. I freed it up but the condition still exists.
Good idea. I can try that. If it's a leak it has to be between the MAF and the Y pipe, correct? All the air is blended after that, correct?
Yes. From the MAF, it goes to the turbo, then a short rubber hose, then a stainless hard pipe, then another rubber hose, then the intercooler, then another rubber hose, then the y-pipe, where it's blended and then flows into the throttle body.
RS6 #1, 01E, 2.5" straight pipes, AMD Stage 1 6MT tune, 460awhp/530awtq on AMD's Mustang dyno. TOTALLED.. RS6 #2, Ebony Black Pearl on black/silver combination with carbon, up and running with 6 gears and AMD tune.
If I cap and pressurize that it should hold air? Do I need to do anything with the wastegate to pressurize the MAF to y pipe? Any other thoughts before I isolate that area tomorrow?
Don't put too much pressure in the wastegate line or you'll pop the diaphragm! Avoid exceeding your "normal" boost pressure there.
EDIT: talking about testing just the "N75 to wastegates" line. But the primary clue for any failures there would be an overboost condition, you don't seem to have that.
If you can get me7logger running - try logging MAF1/MAF2 values or voltages along with boost pressure and ps_w (manifold pressure). It will tell a lot.
I downloaded it just need to give it a try
nubcake, the instructions for the logger say that I need to download my original.B I N file. I have a custom tune that is locked so that I cannot read it. This presents two problems: one is that if I flashback to a stock tune I have to send my ECU to the tuner to be re-flashed with my custom software. Two, the software is locked and I'm not unable to unlock it. Is it absolutely necessary to have the same file in order to use this logger?
You don't need to flash the binary that you download. You just need it to present to logger so it can know memory locations for variables.
The simple option is to run the base file (with same binary version as your tuned one) through ME7info, so it can build the memory map. You can also ask your tuner to run the tuned binary through the ME7info and send you the .ecu file it outputs.
If both won't work, there still is an option. PM for details.
It looks like you are on to something here. I bought 2 new MAF connectors with wires and patched them into the opposite original MAF connectors on the car effectively creating an extension for the wiring and swapping the wiring for each side. My wonky MAF condition went to the other side. So it is not the MAF, or an air leak. It seems that somewhere between the connector plug and the ECU is the cause for my MAF dropping out. I traced the wiring back to the ECU connector for both MAFs and got good readings for continuity and voltage. But maybe it is a wire break or bad connection that is exacerbated by the motor running. Any thoughts? I'm going back out to retest the wiring from the MAF to the ECU.
PS Nubcake, i'm still going to install the NEF Moto logger but i suck at computer and haven't really sat down to get it set up. Given the most recent findings it seems I have almost found the problem though.
A little more info......
Just a recap on the prob: VCDS and logs show the drivers MAF running much lower g/s reading when compared to the passenger side. Often it drops to "0.00 g/s". Passenger side reading goes up and down as expected with smooth consistent values. No fault codes
-Swapping the two MAFs does not swap the problem to the other side so it's not the MAF.
-Swapping the MAF connectors from one side to the other (passenger MAF plugged into the drivers side circuit) does swap the problem to the other side so we know it's not a boost leak, turbo/wastegate issue, etc.
There is some damage to the drivers side connector where the wires enter the plastic plug but it looks very minor. Rather than just cutting into the harness to replace it I ran some tests today. I don't want to hack the end of the harness off only to find out there is a broken wire in a different part of the loom. I used bentley Electrical wiring diagram on page EWD-271 diagram 28/12 at the bottom of the page as a reference.
The tests:
The MAF has a 5 connector plug with holes 2,3,4,5 populated. Results were the same on both drivers plug and passengers.
All female and male plugs look OK to the eye
circuit 2 to ground yields ~13.5 volts
circuit 3 to ecu pin 27 (ECU ground) results in continuity
circuit 4 to ground produces 5 volts
jumping circuit 4 to circuit 3 produces 5 volts
circuit 5 to ecu pin 29/109 (drivers side/passenger) produces continuity
unplugging the drivers MAF makes it idle more smoothly
So, continuity tests mean no broken wires, right? So what gives? Any help on this would be much appreciated. I just can't seem to figure out what the problem could be.
Last edited by UrS6; January 16th, 2017 at 22:48. Reason: added info
Maybe you were on to something when you said "engine running"? Might be a break in the wires close to the plug as there have been a few instances before of it happening as they bend around under the air filter. Engine Tourqe may cause the wire break to open and close the circuit intermittently.
2003 White RS6 2013 Midnight Blue S5
2013 Daytona RS5 2x944 Turbo's 1974 911 w/'91 3.6ltr motor
Roy, WA
At this point maybe I should just redo the end of the harness and keep my fingers crossed? I hate to go hacking into an original harness without some evidence but maybe it's best to rule that out for now. I'm just concerned if I replace the last 6 inches and the problem is at the 10 inch mark.
Custom code in the ECU writing to the "MAF value" memory area. A very long shot, but still a possibility.
If everything else fails (and if you have a backup of your current bin), you could try flashing the original binary.
EDIT: but yea, of course try playing with the wiring first.
Hope it's not that but I don't have a copy of the tune. I can get it but it involves me shipping the ECU which is a pain. And my tune is used on a bunch of cars so I'm assuming it's not that. I hope!Custom code in the ECU writing to the "MAF value" memory area. A very long shot, but still a possibility.
If everything else fails (and if you have a backup of your current bin), you could try flashing the original binary.
EDIT: but yea, of course try playing with the wiring first.
How on earth did you get the wire to reach from drivers side to passenger side and vise versa???? Those friggen wires are soooooo short....
Mike
'18 BMW M5, '19 Porsche Boxster GTS
(prior '94 325is, '97 M3, '00 A6 4.2,'03 RS6,'08 A4 Cab,'13 A8L,'15 Q7,'16 BMW M2,
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