F21 B5 S4 Lean Problems

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tegman88

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	F21 B5 S4 Lean Problems « on: April 15, 2014, 07:45:33 PM »

Hey, I was hoping I could get some help. I'm really losing my mind with this car and am fresh out of ideas.

I keep throwing lean codes for multiplicative fuel trims. After ten minutes of driving my multiplicative LTFT's will be almost maxed out sitting around 20%. Additive stays very close to zero.
This makes me think that my issue is not a vac/boost leak as I feel like it'd have to be a huge leak to throw LTFT off so much and I also think it'd make additive ft's worse than mult.
However, the company who will be tuning the car said it sounds like an intake leak. I've checked and checked and cannot find one. Well, I found a couple minor ones but fixing them made no difference.
I had been thinking the MAF may be the culprit but it's a new (not reman) Hitachi with only about 3k miles on it and it appears to reading proper g/s. At idle I think it's around 5g/s and WOT around 340, which sounds about right to me.
What I think is interesting though is that my car's fuel trim's stay within spec if I drive with the MAF unplugged. This brings me back to thinking of a boost leak.

Here's something else that's interesting. I've cleared faults a number of times and each time I do my idle AFR stays around 19. I can't believe a car will even idle like that. Sometimes it goes back to normal as soon as I start driving. Sometimes, I can cruise and it will stay around 16 or 17.
However, what always makes AFR go back to stoich is a WOT run.

I guess I should probably give more specifics about my setup too lol.
It's a 2000 Audi S4 with an F21 FrankenTurbo kit purchased from Epic Tuning Group. I'm using their 85mm MAF housing with a new Hitachi MAF, 034 conversion harness, EV14 550cc injectors, Walbro 400lph drop in from ProjectB5, stock ignition system (coils only about a year old, BKR7E gapped to .028, and OE ICMS), JHM FMIC, Zeitronix Zt-2, STE PPD for AFR/logging, rebuild 01E from AdvancedAutomotion, FX400 with Fidanza aluminum flywheel.

I have a thread started about this on Audizine already:
http://www.audizine.com/forum/showthread.php/591030-Stage-3-%28F21%29-Lean-Problems?p=9651407#post9651407

Also, I took some logs today using ME7Logger. I haven't quite figured out how to make things look nice with graphs yet but here's the .csv if anyone could take a look:
http://www.datafilehost.com/d/0a30320b

Any suggestions or questions please just let me know.
Thanks a lot for any help.


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tegman88

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	Re: F21 B5 S4 Lean Problems « Reply #1 on: April 15, 2014, 07:54:15 PM »

Something else maybe worth mentioning:
It didn't always throw lean codes. I've been driving it for about a month and at first everything was fine. I wasn't going aggressive with the throttle at all as I was breaking the clutch in and also still had the stock fuel pump.
Once I got a wideband hooked up I did go WOT a few times with the stock pump, keeping a close eye on AFR.
Then I threw lean codes a couple times but it was awhile before these codes would pop up.

Then I changed the fuel pump and started having hard starts. I assumed that fuel pressure was leaking down after sitting and this was just something that went along with the pump. So I continued driving and now lean codes started popping up more frequently.
Eventually I pressure tested and found a bunch of clamps that needed tightened. So I tightened them up, cleared codes and thought I'd be good.
But it continued to get worse and now I drive to work and get the CEL and limp mode.
I also noticed that my fuel pressure doesn't leak down over night. If I leave the engine light on and don't reset the FT's it starts right up the way it used to.

I'm pretty sure that fueling isn't the issue as I'll see AFR 11 close to redline. However, my base tune does seem to run somewhat lean. It stays stoich until like 4krpm and then steadily goes richer until around 11 at 6700rpm.


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tegman88

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	Re: F21 B5 S4 Lean Problems « Reply #2 on: April 15, 2014, 07:57:18 PM »

Also, would it be worth reflashing my ecm?
The only reason I ask is because my car's issues weren't as bad when I first flashed the basemap and seemed to get much worse following fuel pump replacement. Is there maybe some learned behavior in the ecm that doesn't get reset when codes are cleared and maybe the pump is throwing it off?

That makes no sense to me as fuel pressure should be the same but I said I'm out of ideas lol


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nyet

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	Re: F21 B5 S4 Lean Problems « Reply #3 on: April 15, 2014, 07:57:48 PM »

Please post the .csv directly here, i'm not going to download and run an exe ...


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prj

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	Re: F21 B5 S4 Lean Problems « Reply #4 on: April 15, 2014, 11:24:41 PM »

Leave the ECU alone and get back to basics:

1. Proper pressure test with a compressor.
2. Fuel pressure measurement during acceleration.


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tegman88

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	Re: F21 B5 S4 Lean Problems « Reply #5 on: April 16, 2014, 05:17:19 AM »

Quote from: nyet on April 15, 2014, 07:57:48 PM

Please post the .csv directly here, i'm not going to download and run an exe ...

Sorry, I didn't have to download an .exe when I tested it myself but I also didn't realize I could hose files here
.csv below

Quote from: prj on April 15, 2014, 11:24:41 PM

Leave the ECU alone and get back to basics:

1. Proper pressure test with a compressor.
2. Fuel pressure measurement during acceleration.

Ok, I will pressure test again when I'm at work today. I wanted to use our smoke machine too but someone left the tank valve open...
I'll have to work on the fuel pressure measurement though. The PPD has an input for fuel pressure but I don't have a pressure transducer yet. I had kind of ruled a fuel pressure out since, before the CEL comes on, I'll see 11afr at redline.
But I will definitely work on this.

Thanks for your help. Below I attached the ME7Logger .csv and also a less complete .csv which was taken using the PPD. It doesn't have nearly as many variables but it does show AFR. It is one file with a number of pulls in, the very last one I went into limp mode.


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nyet

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	Re: F21 B5 S4 Lean Problems « Reply #6 on: April 16, 2014, 09:03:25 AM »

btw make sure you are logging rl_w and not rl... rl maxes at 191


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tegman88

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	Re: F21 B5 S4 Lean Problems « Reply #7 on: May 07, 2014, 07:48:13 PM »

Thanks for all the replies so far. Tonight I installed a fuel pressure sensor for my PPD and did some logging. I attached the .csv below for anyone who could check it out.
It doesn't have very many variables but it's all I have to log AFR and Fuel Pressure.
I'm not sure what fuel pressure should look like as boost increases but it seems weird to me how it spikes to 80psi at 3500rpm but afr is 14, then fuel pressure is 67 at redline but afr is 11...


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ddillenger

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	Re: F21 B5 S4 Lean Problems « Reply #8 on: May 07, 2014, 08:44:43 PM »

Quote from: tegman88 on May 07, 2014, 07:48:13 PM

Fuel pressure should be 58.8psi PLUS whatever boost you are running. 67psi is too low.


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tegman88

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	Re: F21 B5 S4 Lean Problems « Reply #9 on: June 15, 2014, 07:45:01 PM »

Still trying to sort this out...
I had a thought though. This car has perfect mult fuel trims with the maf unplugged; within 2% of zero. I took this car to a local euro shop and the owner said he would buy a maf housing from a reputable source such as 034 and start with that. He smoke tested and whatnot and couldn't find anything definitively wrong. He thinks I should start with a different housing or that there's an issue with the tune.

My thought is, maybe the tune is for a different size maf? ETG assured me the tune was not the issue; however, on their website where I ordered the kit it states in the description "requires 90mm maf."
The maf I have is 85mm and the filename for the tune says 85mm... but is it possible that the tune is actually for a 90mm maf?
I'm not sure if 5mm smaller than the tune would cause the car to run rich or lean...


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tjwasiak

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	Re: F21 B5 S4 Lean Problems « Reply #10 on: June 15, 2014, 08:36:01 PM »

Quote from: tegman88 on June 15, 2014, 07:45:01 PM

My thought is, maybe the tune is for a different size maf? ETG assured me the tune was not the issue; however, on their website where I ordered the kit it states in the description "requires 90mm maf."
The maf I have is 85mm and the filename for the tune says 85mm... but is it possible that the tune is actually for a 90mm maf?
I'm not sure if 5mm smaller than the tune would cause the car to run rich or lean...

If you run smaller diameter MAF you should be get richer AFR then specified (so fuel trims should be below 0).


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tegman88

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	Re: F21 B5 S4 Lean Problems « Reply #11 on: June 16, 2014, 08:24:19 AM »

That's what I thought but I was hoping I had something there lol. Do you think trying a different housing would be worth it? To me it seems like an 85mm tube is an 85mm tube... and I'm sure there are a lot of other people using the supplied maf housing without issue


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