NefMoto

I am trying to solve for a surging idle condition on an ATQ V6. It would seem that it is not a phenomenon unique to the setup, but common in almost all super charger applications. I would like to try to decipher what Audi has done in tuning their super charged inductions systems to prevent surge at idle.

I know this forum is mostly concerned with turbo applications in the 2.7TT and 1.8T engines. Any thoughts are welcome.

Cheers,

Keith

I have a lot of your G bin defined. Not the entire thing mind you, but quite a bit. Email me.

AFAIK (which isn't everything BTW, so I may be wrong-it's happened one time before) Audi never had a supercharged ME7 application.

What is Audi using on their newest Super Charged 3.0 V6s? Is it a newer version of Motronic?

Definitely MUCH newer. Me7 was done by 05 (in VAG that is).

Simos 8.x IIRC

Boost control. Something you probably lack :)

not necessarily. 2.5 still used me7 all the way up to 07 or 08.

by surging idle do you mean a loopy cam style idle?

Thanks for chiming in guys, I have been away for a while.

It seems the surging idle is perhaps related to the MAF sensor throwing a unexpected high current error. Once the error is present in the ECU memory, the surging idle abates. It is as if the ECU adjusts for the condition and cures itself.

I have yet to test with VCDS, but when I clear the stored error codes using a quick read tool (ECS ScanPro), the surging idle returns until I push it far enough to throw the MAF voltage/current error and then the idle smooths out again. I am not sure, but I suspect the clear stored error codes function on the ScanPro is perhaps also clearing out learned adjustments and returning setting to default.

I have been driving the car on the OE stock ECU for about a week, and I only have seen the bank too rich or lean codes a couple of times, but the car is clearly lacking in power under load and still stumbles and misfires if pressed. I can't complain too loudly as yet, I have a tuned ECU from Josh on my bench to drop in and evaluate, I just have not been able to find a block of time to do so with my laptop riding shotgun logging data with NefMoto and or VCDS.

But I do love the sound of the SC whine. I want to get the base tune sorted soon and start to really look at the refinements to be made down the line over the summer.

Cheers,

Keith

clearing dtc's clears adaption as well.
the maf code is probably because you going beyond the max kg/hr the ecu expects to see (obviously you flowing tons more air with the supercharger).

I'm going to go with incorrect maf/injector scaling on this one. Once the error is thrown the ecu ignores the maf reading and runs off default values.

This is great feedback. I suspected as much as well. Now since I am running on stock ECU, albeit with some fueling issues, should I start from there and try to make the MAF/injector scaling corrections first to see if the stock 7.1 tune with said adjustments can keep up with other adaptations? Or should I try to run the tuned ECU from Josh long enough to get usable LTFT values from logging to see what's happening?

With maf scaling being off I wouldn't think your fuel trims will be relevant. What maf are you running (year, make, model, manufacturer)? Injectors? I've spent some time defining your file, I believe I can help.

Engine is DBW 30V ATQ 2.8L. Original ECU is 3B0 907 551 DB.

ECS Tuning says the MAF is stock 30V Audi/VW part number 078133471. I'll confirm in a few minutes.

The injectors are Audi B5 S4 red-tops, I am attaching a Witch Hunter Performance data sheet from their cleaning, rebuild and flow testing last fall.

FPR is stock 30V Audi/VW 4.0 bar. I just noted that Witch Hunter test pressure was 5.0 bar. Do I need to replace FPR with 5.0 bar unit?

SC is running 3.1" pulley, good for about 7lbs boost at TB assuming a little loss to IC and plumbing. I haven't yet installed boost/vac gauge, so I am going by PES specs and SCAudi.com members' collective knowledge on that figure.

I run only 91+ octane, usually put 93+ from Sunoco in.

Need to move this thread from here to another location?

hitachi maf? Are you sure it isn't the stock sensor in a larger housing?

Yup. Hitachi MAF 078133471E. Here's a pic.

Stock housing? You should measure and compare to a known stock unit.

It is the stock housing (inasmuch as it is original to the car.) If you want dimensions, I can measure openings with caliper.

im going to say the car idles like crap because of all the mismatched hardware and software. car runs and adapts the idle to its liking.
then comes the supercharger, pulling tons more air through the maf than stock, it maxes KFMLDMX and throws a maf signal to high error.
he clears it, clears adaption, and its back to square one.

I think you are both correct. I think that Dacz is probably correct or at least on the right track about the car running on default/learned values after MAF error is posted. k0mpresd you are right on about the clearing codes clears the adaptations.

This setup is working passably as a daily driver because the ECU does not know the increased flow rate of the injectors. The increased air coming through is being mixed with more fuel than stock injectors would have provided and the happy accident is that it works well enough to get by until I can pursue a more resolved solution on both fronts (MAF and injector calibrations). I am wondering if the OE/stock 30V ECU air/fuel/load maps will be a good start if the baselines for the MAF and fuel injectors are updated, or is that not how it works? In my neophyte brain case, I imagine that since the SC boosts air flow in a near direct relationship to engine speed, the air/fuel/load maps would be be pretty close to what would be optimal, except that the scale applied to air and fuel calculations would be greater from idle.

Perhaps tonight I can look at the bins again and once more try to get that toehold of understanding that would make this communication easier from your end and more productive for me towards a better resolved solution. I really appreciate the interest you both have applied towards this.

Cheers,

Keith

Just a thought, but maybe a 2.7 based ecu would be a better fit. It would know what to do with boost.

add map, minus n75. seems like a giant can of worms.

If I run my PC shotgun tomorrow morning, what applications/logging should I do for best perspective on what is happening at stock/reset ECU setup, self-adjusted after MAF error ECU setup and then potentially the same scenarios with Josh's first tune on my original ATQ ECU?

• 1. I have full version of VCDS (KEY II USB)
• 2. I just downloaded NefMoto Flasher Logger 1.9.3.2 and have compatible blue OBD-II dongle
• 3. I have a freshly rebuilt Windows XP Professional SP3 OS ThinkPad dedicated to my VAG tuning

I have a myriad of other minor VAG utilities (VAG Dash, Galletto, VAGTacho) as well, but i think the two above are the only ones that offer real-time logging capabilities.

Do I just drive around? Do I try to spin it up to max revs under load (like a 2nd or 3rd gear pull?) How long do I have to drive for a meaningful data set? Of course all this will perhaps be very clear to me once I get started, but I am just trying to get an idea for how much time I need to steal away from my desk to get this nagging to-do to-did. ;)

have you managed to read your flash? Are you running a stock file?

generally, do a single gear pull from 3000 rpm to redline, unless there is a specific thing you are trying to debug (idle, warmup, shifts, etc).

2nd generally goes by too quickly unless you have a very slow car :)